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A Generalization of Graham’s Estimate
on the Barban-Vehov Problem

Chen An Duke University, 120 Science Drive, Durham NC 27708 chen.an@duke.edu, chen.an.nku@gmail.com
Abstract.

Suppose {λd}\{\lambda_{d}\} are Selberg’s sieve weights and 1w<yx1\leq w<y\leq x. Graham’s estimate on the Barban-Vehov problem shows that 1nx(d|nλd)2=xlog(y/w)+O(xlog2(y/w))\sum_{1\leq n\leq x}(\sum_{d|n}\lambda_{d})^{2}=\frac{x}{\log(y/w)}+O(\frac{x}{\log^{2}(y/w)}). We prove an analogue of this estimate for a sum over ideals of an arbitrary number field kk. Our asymptotic estimate remains the same; the only difference is that the effective error term may depend on arithmetics of kk. Our innovation involves multiple counting results on ideals instead of integers. Notably, some of the results are nontrivial generalizations. Furthermore, we prove a corollary that leads to a new zero density estimate.

1. Introduction

Fix 1w<y1\leq w<y. For any positive integer dd, define

m(d):={1dw,log(y/d)log(y/w)w<dy,0d>y,m(d):=\begin{cases}1&d\leq w,\\ \frac{\log(y/d)}{\log(y/w)}&w<d\leq y,\\ 0&d>y,\end{cases}

and define λd:=μ(d)m(d)\lambda_{d}:=\mu(d)m(d), for the Möbius function μ(d)\mu(d). The set {λd}d1\{\lambda_{d}\}_{d\geq 1} is the set of Selberg sieve weights. Barban and Vehov [BV68] proposed a problem on estimating the sum 1nx(d|nλd)2\sum_{1\leq n\leq x}(\sum_{d|n}\lambda_{d})^{2} for any xyx\geq y. They proved an upper bound xlog(y/w).\ll\frac{x}{\log(y/w)}. This bound was made asymptotic by Graham [Gra78], who showed

(1.1) 1nx(d|nλd)2=xlog(y/w)+O(xlog2(y/w)).\sum_{1\leq n\leq x}\left(\sum_{d|n}\lambda_{d}\right)^{2}=\frac{x}{\log(y/w)}+O\left(\frac{x}{\log^{2}(y/w)}\right).

Equation (1.1) has applications to zero density estimates and primes in arithmetic progressions, including Linnik’s constant. Further generalizations on the Barban-Vehov problem have been made by, e.g., Jutila [Jut79], and Murty [Mur18]. Such improvements either regard generalizing the summand or imposing a congruence condition on the sum over nn.

The purpose of this paper is to generalize the asymptotic estimate (1.1) to an arbitrary base field kk rather than the base field {\mathbb{Q}}, i.e., the sum is taken over ideals in 𝒪k{\mathscr{O}}_{k} instead of positive integers. In particular, we will define the Selberg sieve weights for ideals and prove the following Theorem 1.1. Our aim to generalize the Barban-Vehov problem is three-fold. First, Theorem 1.1 leads to a new zero density estimate via Corollary 1.2. Second, it is a natural but nontrivial generalization from a sum of integers to a sum of ideals. During the proof of Theorem 1.1, we need to introduce multiple lemmas on estimating arithmetic functions related to ideals. Third, our Theorem 1.1 and Corollary 1.2 below are expected to have wide applications to methods involving the large sieve, over an arbitrary number field.

For any ideal 𝔫{\mathfrak{n}} of 𝒪k{\mathscr{O}}_{k}, define

μk(𝔫):={(1)s if 𝔫 is a product of s distinct prime ideals,0 otherwise.\mu_{k}({\mathfrak{n}}):=\begin{cases}(-1)^{s}&\text{ if }{\mathfrak{n}}\text{ is a product of }s\text{ distinct prime ideals,}\\ 0&\text{ otherwise.}\end{cases}

Define

λ𝔫:=μk(𝔫)m(N𝔫).\lambda_{\mathfrak{n}}:=\mu_{k}({\mathfrak{n}})m({\mathrm{N}}{\mathfrak{n}}).

Denote 𝔡|𝔫{\mathfrak{d}}|{\mathfrak{n}} if 𝔫𝔡{\mathfrak{n}}\subseteq{\mathfrak{d}} and denote nk=[k:],dk=disc(k/)n_{k}=[k:{\mathbb{Q}}],d_{k}=\text{disc}(k/{\mathbb{Q}}). Denote β0\beta_{0} to be the possible (real, simple) Siegel zero for kk (see Definition 3.8 for its definition). In particular, 12<β0<1\frac{1}{2}<\beta_{0}<1.

Our main theorem is the following.

Theorem 1.1.

Let kk be a number field of degree nkn_{k} and discriminant dkd_{k}, and let 1w<yx1\leq w<y\leq x. Then we have

𝔫𝒪k,N𝔫x(𝔡|𝔫λ𝔡)2=xlog(y/w)+Onk,dk(Cβ0xlog2(y/w)).\sum_{\begin{subarray}{c}{\mathfrak{n}}\subseteq{\mathscr{O}}_{k},{\mathrm{N}}{\mathfrak{n}}\leq x\end{subarray}}\left(\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\lambda_{\mathfrak{d}}\right)^{2}=\frac{x}{\log(y/w)}+O_{n_{k},d_{k}}(\frac{C_{\beta_{0}}x}{\log^{2}(y/w)}).

where we may take Cβ0=1(1β0)6Dβ02C_{\beta_{0}}=\frac{1}{(1-\beta_{0})^{6}D_{\beta_{0}}^{2}} with Dβ0=min{1,|ζk(β0)|}D_{\beta_{0}}=\min\{1,|\zeta_{k}^{{}^{\prime}}(\beta_{0})|\} if β0\beta_{0} exists and Cβ0=1C_{\beta_{0}}=1 otherwise.

Theorem 1.1 appears to be the first theorem that provides an asymptotic estimate to the Barban-Vehov problem for a base field other than {\mathbb{Q}}. When the base field is {\mathbb{Q}}, Graham’s estimate (1.1) is currently the best bound, and the quality of our asymptotic estimate matches the one given by Graham. For the proof of Theorem 1.1, we follow the outline of Graham’s approach while proving a series of new estimates with modified methods. These methods allow us to overcome obstacles when we work over an arbitrary base field. A few highlights of these methods are in the proofs of Lemmas 3.5, 3.6, and 3.9. Our notation differs from Graham since our notation naturally derives from an application of zero density estimates in our work on the large sieve in [An20]. However, there is a correspondence: our x,w,yx,w,y correspond to Graham’s N,z1,z2N,z_{1},z_{2}.

Theorem 1.1 leads to the following Corollary 1.2, which is a crucial ingredient to prove a new zero density estimate. The approach from Corollary 1.2 to the zero density estimate is proved in the companion paper [An20].

Corollary 1.2.

Let kk be a number field of degree nkn_{k} and discriminant dkd_{k}, and let 1w<yx1\leq w<y\leq x. For any α\alpha with 1/2<α<11/2<\alpha<1,

𝔫𝒪k,N𝔫x(𝔡|𝔫λ𝔡)2N𝔫12αnk,dkCβ0log(x/w)log(y/w)x22α,\sum_{\begin{subarray}{c}{\mathfrak{n}}\subseteq{\mathscr{O}}_{k},{\mathrm{N}}{\mathfrak{n}}\leq x\end{subarray}}\left(\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\lambda_{\mathfrak{d}}\right)^{2}{\mathrm{N}}{\mathfrak{n}}^{1-2\alpha}\ll_{n_{k},d_{k}}C_{\beta_{0}}\frac{\log(x/w)}{\log(y/w)}x^{2-2\alpha},

where Cβ0C_{\beta_{0}} is as in Theorem 1.1.

When the base field is {\mathbb{Q}}, this recovers Lemma 9 in [Gra81]. We reserve the proof of Corollary 1.2 to the end of the paper, in Section 6.

Now, we outline the proof of Theorem 1.1. It is a consequence of the following Theorem 1.3; we deduce Theorem 1.1 from Theorem 1.3 in Section 6.

Let w<yw<y be as in Theorem 1.1. For ideals 𝔡,𝔢{\mathfrak{d}},{\mathfrak{e}} of 𝒪k{\mathscr{O}}_{k}, define

(1.2) Λ1(𝔡)={μk(𝔡)log(wN𝔡) if N𝔡w,0 if N𝔡>w,Λ2(𝔢)={μk(𝔢)log(yN𝔢) if N𝔢y,0 if N𝔢>y.\Lambda_{1}({\mathfrak{d}})=\begin{cases}\mu_{k}({\mathfrak{d}})\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})&\text{ if }{\mathrm{N}}{\mathfrak{d}}\leq w,\\ 0&\text{ if }{\mathrm{N}}{\mathfrak{d}}>w,\end{cases}\ \ \ \ \ \ \ \ \ \ \ \ \ \Lambda_{2}({\mathfrak{e}})=\begin{cases}\mu_{k}({\mathfrak{e}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})&\text{ if }{\mathrm{N}}{\mathfrak{e}}\leq y,\\ 0&\text{ if }{\mathrm{N}}{\mathfrak{e}}>y.\end{cases}
Theorem 1.3.

Let kk be a number field of degree nkn_{k} and discriminant dkd_{k}, and let 1w<yx1\leq w<y\leq x. We have

N𝔫x(𝔡|𝔫Λ1(𝔡))(𝔢|𝔫Λ2(𝔢))=xlogw+Onk,dk(Cβ0x),\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\Lambda_{1}({\mathfrak{d}})\right)\left(\sum_{{\mathfrak{e}}|{\mathfrak{n}}}\Lambda_{2}({\mathfrak{e}})\right)=x\log w+O_{n_{k},d_{k}}\left(C_{\beta_{0}}x\right),

where Cβ0C_{\beta_{0}} is as in Theorem 1.1.

If nk=1n_{k}=1, Theorem 1.3 recovers Theorem in [Gra78, p.84]. So we suppose nk2n_{k}\geq 2 throughout the paper. To compute the left-hand side in Theorem 1.3, we follow Graham [Gra78] to consider the cases wyxwy\leq x and wy>xwy>x separately. In the former case, it is straightforward to obtain our estimate. In the latter case, a small arithmetic trick is needed before our computation (see (5.1)), generalizing a trick developed in Graham’s work. The rest of the computation relies heavily on the series of new estimates on arithmetics related to ideals. Among these estimates, the generalized Möbius function μk(𝔫)\mu_{k}({\mathfrak{n}}) plays a vital role. Its oscillating nature makes our method possible; see the statements from Lemma 3.9 to Lemma 3.12. Our argument’s error terms may have dependencies on nk,dkn_{k},d_{k}, which originate in our estimates. In our work below, we omit the notation on these dependencies for simplicity.

The outline of our paper is as follows. In Section 2, we provide a list of notations. In Section 3, we provide all necessary lemmas in the paper. In Section 4, we prove Theorem 1.3 in the case wyxwy\leq x. In Section 5, we prove Theorem 1.3 in the case wy>xwy>x. In Section 6, we deduce Theorem 1.1 from Theorem 1.3, deduce Corollary 1.2 from Theorem 1.1, and prove all the lemmas.

2. Notations

In this section, we provide a list of notations and functions supported on ideals in 𝒪k{\mathscr{O}}_{k}. These functions are generalizations of standard arithmetic functions. All the Gothic letters are ideals and all the ideals 𝔭{\mathfrak{p}} are prime ideals.

  • squarefree ideals = ideals 𝔫{\mathfrak{n}} of the form 𝔫=𝔭1𝔭2𝔭s{\mathfrak{n}}={\mathfrak{p}}_{1}{\mathfrak{p}}_{2}\dots\mathfrak{p}_{s}, where 𝔭1,,𝔭s{\mathfrak{p}}_{1},\dots,{\mathfrak{p}}_{s} are distinct prime ideals

  • ω(𝔫)=\omega({\mathfrak{n}})= number of distinct prime ideal divisors of 𝔫{\mathfrak{n}}

  • (𝔡,𝔢)=({\mathfrak{d}},{\mathfrak{e}})= the smallest ideal that contains both 𝔡{\mathfrak{d}} and 𝔢{\mathfrak{e}}; 𝔡,𝔢{\mathfrak{d}},{\mathfrak{e}} are relatively prime means (𝔡,𝔢)=(1)({\mathfrak{d}},{\mathfrak{e}})=(1)

  • [𝔡,𝔢]=[{\mathfrak{d}},{\mathfrak{e}}]= the largest ideal that is contained in both 𝔡{\mathfrak{d}} and 𝔢{\mathfrak{e}}

  • Euler totient function for ideals φ(𝔫)=N𝔫𝔭|𝔫(11N𝔭)\varphi({\mathfrak{n}})={\mathrm{N}}{\mathfrak{n}}\prod_{{\mathfrak{p}}|{\mathfrak{n}}}(1-\frac{1}{{\mathrm{N}}{\mathfrak{p}}})

  • divisor function for ideals d(𝔫)=𝔡|𝔫1=d({\mathfrak{n}})=\sum_{{\mathfrak{d}}|{\mathfrak{n}}}1= the number of divisors of 𝔫{\mathfrak{n}}

  • Liouville function for ideals λ(𝔫)=(1)k1++ks\lambda({\mathfrak{n}})=(-1)^{k_{1}+\dots+k_{s}} if 𝔫=𝔭1k1𝔭sks{\mathfrak{n}}={\mathfrak{p}}_{1}^{k_{1}}\dots\mathfrak{p}_{s}^{k_{s}}, where 𝔭1,,𝔭s{\mathfrak{p}}_{1},\dots,{\mathfrak{p}}_{s} are distinct prime ideals

  • von Mangoldt function for ideals

    Λ(𝔫)={log(N𝔭), if 𝔫=𝔭m for some positive integer m0, otherwise\Lambda({\mathfrak{n}})=\begin{cases}\log({\mathrm{N}}{\mathfrak{p}}),&\text{ if }{\mathfrak{n}}={\mathfrak{p}}^{m}\text{ for some positive integer }m\\ 0,&\text{ otherwise}\end{cases}
  • κ(𝔫)=N𝔫𝔭|𝔫(1+1N𝔭)\kappa({\mathfrak{n}})={\mathrm{N}}{\mathfrak{n}}\prod_{{\mathfrak{p}}|{\mathfrak{n}}}(1+\frac{1}{{\mathrm{N}}{\mathfrak{p}}})

  • σa(𝔫)=𝔡|𝔫N𝔡a\sigma_{a}({\mathfrak{n}})=\sum_{{\mathfrak{d}}|{\mathfrak{n}}}{\mathrm{N}}{\mathfrak{d}}^{a}

3. Statements of All Lemmas

In this section, we state all the technical lemmas used later in our proof. All of the lemmas are counting results on arithmetic objects related to ideals. The lemmas up to Lemma 3.7 are non-oscillating results, i.e., summing over nonnegative values, whereas the lemmas from Lemma 3.9 onward are oscillating results, since the sum involves μk\mu_{k}.

Let Q1Q\geq 1 be a real number. In all the results below, the number QQ always serves as the bound of ideal norms. We first provide a theorem that is a weaker version of [LDTT22, Theorem 3], and all the other lemmas elaborate on statements of this type.

Theorem A.

[LDTT22, Theorem 3 (weak version)] There exists an absolute constant sk>0s_{k}>0 such that

N𝔫Q1=skQ+O(Q11nk),\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}1=s_{k}Q+O(Q^{1-\frac{1}{n_{k}}}),

where

sk=2r1(2π)r2hRw|dk|,s_{k}=\frac{2^{r_{1}}(2\pi)^{r_{2}}hR}{w\sqrt{|d_{k}|}},

r1r_{1} is the number of real embeddings of kk within a fixed choice of ¯\overline{{\mathbb{Q}}}, r2r_{2} is the number of pairs of complex embeddings of kk within ¯\overline{{\mathbb{Q}}}, hh is the class number of kk, RR is the regulator, ww is the number of roots of unity, and the constant associated to the error term is effective.

Using the class number formula, we have sk=Ress=1ζk(s)s_{k}=\mathrm{Res}_{s=1}\zeta_{k}(s). Our error term in Theorem A is weaker than [LDTT22, Theorem 3] but is sufficient for our purpose.

Now we are ready to state our lemmas. The proofs are reserved to Section 6.

Lemma 3.1.

For any constant 0<a10<a\leq 1, we have

N𝔫QN𝔫a={sk1aQ1a+O(Q11nka)+O(1) if 0<a<11nk or 11nk<a<1,sknkQ1nk+O(logQ) if a=11nk,sklogQ+O(1) if a=1..\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\end{subarray}}{\mathrm{N}}{\mathfrak{n}}^{-a}=\begin{cases}\frac{s_{k}}{1-a}Q^{1-a}+O(Q^{1-\frac{1}{n_{k}}-a})+O(1)&\text{ if }0<a<1-\frac{1}{n_{k}}\text{ or }1-\frac{1}{n_{k}}<a<1,\\ s_{k}n_{k}Q^{\frac{1}{n_{k}}}+O(\log Q)&\text{ if }a=1-\frac{1}{n_{k}},\\ s_{k}\log Q+O(1)&\text{ if }a=1.\end{cases}.
Lemma 3.2.

For the constant a=11nka=1-\frac{1}{n_{k}}, we have

N𝔫Qlog(QN𝔫)N𝔫a=sknk2Q1nk+O((logQ)2).\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\end{subarray}}\frac{\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}})}{{\mathrm{N}}{\mathfrak{n}}^{a}}=s_{k}n_{k}^{2}Q^{\frac{1}{n_{k}}}+O((\log Q)^{2}).

Recall the function σa\sigma_{a} defined in Section 2.

Lemma 3.3.

If a<0a<0, then

N𝔫Qσa(𝔫)N𝔫Qσa2(𝔫)aQ.\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\sigma_{a}({\mathfrak{n}})\leq\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\sigma_{a}^{2}({\mathfrak{n}})\ll_{a}Q.
Lemma 3.4.

We have

N𝔫Q1N𝔫(log(2QN𝔫))2=O(1).\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{1}{{\mathrm{N}}{\mathfrak{n}}(\log(\frac{2Q}{{\mathrm{N}}{\mathfrak{n}}}))^{2}}=O(1).

For any a<0a<0 and 0<b10<b\leq 1,

N𝔫Qσa2(𝔫)N𝔫b(log(2QN𝔫))2=O(Q1b).\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{\sigma_{a}^{2}({\mathfrak{n}})}{{\mathrm{N}}{\mathfrak{n}}^{b}(\log(\frac{2Q}{{\mathrm{N}}{\mathfrak{n}}}))^{2}}=O(Q^{1-b}).

In our proof of Theorem 1.3, squarefree ideals are important. The next three lemmas involve such ideals.

Lemma 3.5.

We have

N𝔫Qμk2(𝔫)φ(𝔫)=sklogQ+O(1).\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{\mu_{k}^{2}({\mathfrak{n}})}{\varphi({\mathfrak{n}})}=s_{k}\log Q+O(1).
Lemma 3.6.

We have

N𝔫Qμk2(𝔫)=skζk(2)Q+O(Q11nk+εk),\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\mu_{k}^{2}({\mathfrak{n}})=\frac{s_{k}}{\zeta_{k}(2)}Q+O(Q^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}),

where εk=0{\varepsilon}_{k}=0 for nk3n_{k}\geq 3 and εk>0{\varepsilon}_{k}>0 is arbitrarily small for nk=2n_{k}=2.

Lemma 3.7.

For any squarefree integral ideal 𝔯{\mathfrak{r}} in 𝒪k{\mathscr{O}}_{k}, we have

N𝔫Q(𝔫,𝔯)=(1)μk2(𝔫)=skζk(2)N𝔯κ(𝔯)Q+O(Q11nk+εkσ1nk+1(𝔯)),\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\mu_{k}^{2}({\mathfrak{n}})=\frac{s_{k}}{\zeta_{k}(2)}\frac{{\mathrm{N}}{\mathfrak{r}}}{\kappa({\mathfrak{r}})}Q+O(Q^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}})),

where εk{\varepsilon}_{k} is as in Lemma 3.6.

The six statements in the next four lemmas have their respective analogues as (6), (7), (8), (10), (11), and (12) in Graham’s paper [Gra78]. In all the lemmas above, the implied constants are effectively computable. Before we state the lemmas, we need to introduce a zero-free region for the Dedekind zeta function ζk(s)\zeta_{k}(s).

Theorem B.

[IK04, Theorem 5.33] There exists an absolute constant c>0c>0 such that ζk(s)(s=σ+it)\zeta_{k}(s)(s=\sigma+it) has no zero in the region

σ1cnk2log|dk|(|t|+3)nk,\sigma\geq 1-\frac{c}{n_{k}^{2}\log|d_{k}|(|t|+3)^{n_{k}}},

except possibly a simple real zero β0<1\beta_{0}<1.

Definition 3.8.

If the zero β0\beta_{0} exists, then it is called a Siegel zero.

Our next lemmas now explicitly denote any (possible) dependence on β0\beta_{0}.

Lemma 3.9.

For any A>0A>0, the following bounds hold:

(3.1) N𝔫Qμk(𝔫)Qβ0β0ζk(β0)AQ(log2Q)A.\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\mu_{k}({\mathfrak{n}})-\frac{Q^{\beta_{0}}}{\beta_{0}\zeta_{k}^{{}^{\prime}}(\beta_{0})}\ll_{A}Q(\log 2Q)^{-A}.

The term involving β0{\beta_{0}} exists if and only if the Siegel zero exists (and similarly for the expressions below). Second,

(3.2) N𝔫Qμk(𝔫)N𝔫Qβ01(β01)ζk(β0)A(log2Q)A.\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{\mu_{k}({\mathfrak{n}})}{{\mathrm{N}}{\mathfrak{n}}}-\frac{Q^{\beta_{0}-1}}{(\beta_{0}-1)\zeta_{k}^{{}^{\prime}}(\beta_{0})}\ll_{A}(\log 2Q)^{-A}.

Third,

(3.3) N𝔫Qμk(𝔫)logN𝔫N𝔫=1sk+Qβ01[(β01)logQ1](β01)2ζk(β0)+OA((log2Q)A).\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{\mu_{k}({\mathfrak{n}})\log{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{n}}}=-\frac{1}{s_{k}}+\frac{Q^{\beta_{0}-1}[(\beta_{0}-1)\log Q-1]}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}+O_{A}((\log 2Q)^{-A}).

For convenience, define

Cβ0:={max{1,1(β01)2|ζk(β0)|} if β0 exists,1otherwise.C_{\beta_{0}}^{{}^{\prime}}:=\begin{cases}\max\{1,\frac{1}{(\beta_{0}-1)^{2}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}\}&\text{ if }\beta_{0}\text{ exists},\\ 1&\text{otherwise}.\end{cases}

This quantity will appear frequently in our bounds.

Lemma 3.10.

For any squarefree integral ideal 𝔯{\mathfrak{r}} in 𝒪k{\mathscr{O}}_{k} and any A>0A>0,

N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)N𝔫log(QN𝔫)=N𝔯skφ(𝔯)+C𝔯,β0Qβ01+OA(Cβ0σ12(𝔯)(log2Q)A),\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{{\mathrm{N}}{\mathfrak{n}}}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}})=\frac{{\mathrm{N}}{\mathfrak{r}}}{s_{k}\varphi({\mathfrak{r}})}+C_{{\mathfrak{r}},\beta_{0}}Q^{\beta_{0}-1}+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-A}),

where C𝔯,β0C_{{\mathfrak{r}},\beta_{0}} is a constant depending only on 𝔯,β0{\mathfrak{r}},\beta_{0}, and |C𝔯,β0|Cβ0σ12(𝔯)|C_{{\mathfrak{r}},\beta_{0}}|\leq C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}}).

Recall the definition of κ(𝔫)\kappa({\mathfrak{n}}) in Section 2.

Lemma 3.11.

For any squarefree integral ideal 𝔯{\mathfrak{r}} in 𝒪k{\mathscr{O}}_{k} and any A>0A>0,

N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)log(QN𝔫)=κ(𝔯)N𝔯ζk(2)sk+C𝔯,β0Qβ01+OA(Cβ0σ12(𝔯)(log2Q)A),\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}})=\frac{\kappa({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}}\frac{\zeta_{k}(2)}{s_{k}}+C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-A}),

where C𝔯,β0C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}} is a constant depending only on 𝔯,β0{\mathfrak{r}},\beta_{0}, and |C𝔯,β0|Cβ0σ12(𝔯)|C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}|\ll C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}}).

Lemma 3.12.

For any squarefree integral ideal 𝔯{\mathfrak{r}} in 𝒪k{\mathscr{O}}_{k} and any A>0A>0,

N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)=OA(C𝔯,β0(1β0)Qβ01+Cβ0σ12(𝔯)(log2Q)A),\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})}=O_{A}(C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}(1-\beta_{0})Q^{\beta_{0}-1}+C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-A}),

where C𝔯,β0C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}} is as in Lemma 3.11.

All these lemmas are proved in Section 6. We now assume the above lemmas and prove Theorem 1.3.

4. Proof of Theorem 1.3 in the case wyxwy\leq x

Recall the functions Λ1\Lambda_{1} and Λ2\Lambda_{2} defined in (1.2). We write

(4.1) 1<N𝔫x(𝔡|𝔫Λ1(𝔡))(𝔢|𝔫Λ2(𝔢))\displaystyle\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\Lambda_{1}({\mathfrak{d}})\right)\left(\sum_{{\mathfrak{e}}|{\mathfrak{n}}}\Lambda_{2}({\mathfrak{e}})\right) =\displaystyle= 1<N𝔫x[𝔡,𝔢]|𝔫Λ1(𝔡)Λ2(𝔢)\displaystyle\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\sum_{[{\mathfrak{d}},{\mathfrak{e}}]|{\mathfrak{n}}}\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})
=\displaystyle= 𝔡,𝔢N([𝔡,𝔢])xΛ1(𝔡)Λ2(𝔢)𝔫[𝔡,𝔢]|𝔫1<N𝔫x1.\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])\leq x\end{subarray}}\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})\sum_{\begin{subarray}{c}{\mathfrak{n}}\\ [{\mathfrak{d}},{\mathfrak{e}}]|{\mathfrak{n}}\\ 1<{\mathrm{N}}{\mathfrak{n}}\leq x\end{subarray}}1.

So we can apply Theorem A and write the sum in (4.1) as

(4.2) 𝔡,𝔢N𝔡wN𝔢yΛ1(𝔡)Λ2(𝔢)skxN([𝔡,𝔢])+O(x11nk𝔡,𝔢N𝔡wN𝔢ylog(wN𝔡)log(yN𝔢)N([𝔡,𝔢])11nk).\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})\frac{s_{k}x}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])}+O(x^{1-\frac{1}{n_{k}}}\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\frac{\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])^{1-\frac{1}{n_{k}}}}).

To deal with the error term in (4.2), we need to use the Euler totient function for ideals φ(𝔫)\varphi({\mathfrak{n}}) defined in Section 2. Similar to the standard Euler totient function, the function φ(𝔫)\varphi({\mathfrak{n}}) satisfies the identity N𝔫=𝔯|𝔫φ(𝔯){\mathrm{N}}{\mathfrak{n}}=\sum_{{\mathfrak{r}}|{\mathfrak{n}}}\varphi({\mathfrak{r}}).

Now we compute

𝔡,𝔢N𝔡wN𝔢ylog(wN𝔡)log(yN𝔢)N([𝔡,𝔢])11nk\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\frac{\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])^{1-\frac{1}{n_{k}}}} =\displaystyle= 𝔡,𝔢N𝔡wN𝔢ylog(wN𝔡)log(yN𝔢)(N𝔡N𝔢)11nkN(𝔡,𝔢)11nk\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\frac{\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})}{({\mathrm{N}}{\mathfrak{d}}{\mathrm{N}}{\mathfrak{e}})^{1-\frac{1}{n_{k}}}}{\mathrm{N}}({\mathfrak{d}},{\mathfrak{e}})^{1-\frac{1}{n_{k}}}
=\displaystyle= 𝔡,𝔢N𝔡wN𝔢ylog(wN𝔡)log(yN𝔢)(N𝔡N𝔢)11nk(𝔯|(𝔡,𝔢)φ(𝔯))11nk\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\frac{\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})}{({\mathrm{N}}{\mathfrak{d}}{\mathrm{N}}{\mathfrak{e}})^{1-\frac{1}{n_{k}}}}(\sum_{{\mathfrak{r}}|({\mathfrak{d}},{\mathfrak{e}})}\varphi({\mathfrak{r}}))^{1-\frac{1}{n_{k}}}
\displaystyle\leq 𝔡,𝔢N𝔡wN𝔢ylog(wN𝔡)log(yN𝔢)(N𝔡N𝔢)11nk(𝔯|(𝔡,𝔢)φ(𝔯)11nk)\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\frac{\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})}{({\mathrm{N}}{\mathfrak{d}}{\mathrm{N}}{\mathfrak{e}})^{1-\frac{1}{n_{k}}}}(\sum_{{\mathfrak{r}}|({\mathfrak{d}},{\mathfrak{e}})}\varphi({\mathfrak{r}})^{1-\frac{1}{n_{k}}})
=\displaystyle= 𝔯N𝔯wφ(𝔯)11nkN𝔯22nk(𝔪N𝔪wN𝔯log(wN𝔪N𝔯)N𝔪11nk)(𝔫N𝔫yN𝔯log(yN𝔫N𝔯)N𝔫11nk).\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq w\end{subarray}}\frac{\varphi({\mathfrak{r}})^{1-\frac{1}{n_{k}}}}{{\mathrm{N}}{\mathfrak{r}}^{2-\frac{2}{n_{k}}}}\left(\sum_{\begin{subarray}{c}{\mathfrak{m}}\\ {\mathrm{N}}{\mathfrak{m}}\leq\frac{w}{{\mathrm{N}}{\mathfrak{r}}}\end{subarray}}\frac{\log(\frac{w}{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{r}}})}{{\mathrm{N}}{\mathfrak{m}}^{1-\frac{1}{n_{k}}}}\right)\left(\sum_{\begin{subarray}{c}{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{n}}\leq\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\end{subarray}}\frac{\log(\frac{y}{{\mathrm{N}}{\mathfrak{n}}{\mathrm{N}}{\mathfrak{r}}})}{{\mathrm{N}}{\mathfrak{n}}^{1-\frac{1}{n_{k}}}}\right).

The inequality above is an application of Hölder’s inequality. By Lemma 3.2 and Lemma 3.1 (in the case a=1a=1), the expression above is equal to

(4.3) =\displaystyle= 𝔯N𝔯wφ(𝔯)11nkN𝔯22nk(sknk2(wN𝔯)1nk+O((logwN𝔯)2))(sknk2(yN𝔯)1nk+O((logyN𝔯)2))\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq w\end{subarray}}\frac{\varphi({\mathfrak{r}})^{1-\frac{1}{n_{k}}}}{{\mathrm{N}}{\mathfrak{r}}^{2-\frac{2}{n_{k}}}}\left(s_{k}n_{k}^{2}(\frac{w}{{\mathrm{N}}{\mathfrak{r}}})^{\frac{1}{n_{k}}}+O((\log\frac{w}{{\mathrm{N}}{\mathfrak{r}}})^{2})\right)\left(s_{k}n_{k}^{2}(\frac{y}{{\mathrm{N}}{\mathfrak{r}}})^{\frac{1}{n_{k}}}+O((\log\frac{y}{{\mathrm{N}}{\mathfrak{r}}})^{2})\right)
=\displaystyle= sk2nk4(wy)1nk𝔯N𝔯wφ(𝔯)11nkN𝔯2+O(y1nk(logw)2𝔯N𝔯w1N𝔯)\displaystyle s_{k}^{2}n_{k}^{4}(wy)^{\frac{1}{n_{k}}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq w\end{subarray}}\frac{\varphi({\mathfrak{r}})^{1-\frac{1}{n_{k}}}}{{\mathrm{N}}{\mathfrak{r}}^{2}}+O(y^{\frac{1}{n_{k}}}(\log w)^{2}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq w\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{r}}})
=\displaystyle= sk2nk4(wy)1nk𝔯N𝔯wφ(𝔯)11nkN𝔯2+O(y1nk(logw)3)\displaystyle s_{k}^{2}n_{k}^{4}(wy)^{\frac{1}{n_{k}}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq w\end{subarray}}\frac{\varphi({\mathfrak{r}})^{1-\frac{1}{n_{k}}}}{{\mathrm{N}}{\mathfrak{r}}^{2}}+O(y^{\frac{1}{n_{k}}}(\log w)^{3})
=\displaystyle= O((wy)1nk).\displaystyle O((wy)^{\frac{1}{n_{k}}}).

After multiplying by x11nkx^{1-\frac{1}{n_{k}}}, this shows that the error term in (4.2) is O(x)O(x).

For the main term in (4.2), we compute

𝔡,𝔢Λ1(𝔡)Λ2(𝔢)N([𝔡,𝔢])\displaystyle\sum_{{\mathfrak{d}},{\mathfrak{e}}}\frac{\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])} =\displaystyle= 𝔡,𝔢Λ1(𝔡)Λ2(𝔢)N(𝔡𝔢)N((𝔡,𝔢)).\displaystyle\sum_{{\mathfrak{d}},{\mathfrak{e}}}\frac{\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})}{{\mathrm{N}}({\mathfrak{d}}{\mathfrak{e}})}{\mathrm{N}}(({\mathfrak{d}},{\mathfrak{e}})).

Thus,

𝔡,𝔢Λ1(𝔡)Λ2(𝔢)N([𝔡,𝔢])\displaystyle\sum_{{\mathfrak{d}},{\mathfrak{e}}}\frac{\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])}
=\displaystyle= 𝔡,𝔢Λ1(𝔡)Λ2(𝔢)N(𝔡𝔢)𝔯|(𝔡,𝔢)φ(𝔯)\displaystyle\sum_{{\mathfrak{d}},{\mathfrak{e}}}\frac{\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})}{{\mathrm{N}}({\mathfrak{d}}{\mathfrak{e}})}\sum_{{\mathfrak{r}}|({\mathfrak{d}},{\mathfrak{e}})}\varphi({\mathfrak{r}})
=\displaystyle= N𝔯wμk2(𝔯)φ(𝔯)N𝔯2(N𝔪wN𝔯(𝔪,𝔯)=(1)μk(𝔪)N𝔪log(wN𝔪N𝔯))(N𝔫yN𝔯(𝔫,𝔯)=(1)μk(𝔫)N𝔫log(yN𝔫N𝔯)).\displaystyle\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})\varphi({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{2}}\left(\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{m}}\leq\frac{w}{{\mathrm{N}}{\mathfrak{r}}}\\ ({\mathfrak{m}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{m}})}{{\mathrm{N}}{\mathfrak{m}}}\log(\frac{w}{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{r}}})\right)\left(\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{{\mathrm{N}}{\mathfrak{n}}}\log(\frac{y}{{\mathrm{N}}{\mathfrak{n}}{\mathrm{N}}{\mathfrak{r}}})\right).

We expand the expression. To start, by Lemma 3.10,

(4.4) 𝔡,𝔢Λ1(𝔡)Λ2(𝔢)N([𝔡,𝔢])\displaystyle\sum_{{\mathfrak{d}},{\mathfrak{e}}}\frac{\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])}
=\displaystyle= N𝔯wμk2(𝔯)φ(𝔯)N𝔯2(N𝔯skφ(𝔯)+C𝔯,β0(wN𝔯)β01+O(Cβ0σ1/2(𝔯)(log2wN𝔯)2))2\displaystyle\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})\varphi({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{2}}\left(\frac{{\mathrm{N}}{\mathfrak{r}}}{s_{k}\varphi({\mathfrak{r}})}+C_{{\mathfrak{r}},\beta_{0}}(\frac{w}{{\mathrm{N}}{\mathfrak{r}}})^{\beta_{0}-1}+O(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-1/2}({\mathfrak{r}})(\log\frac{2w}{{\mathrm{N}}{\mathfrak{r}}})^{-2})\right)^{2}
=\displaystyle= 1sk2N𝔯wμk2(𝔯)φ(𝔯)+w2β02N𝔯wC𝔯,β02μk2(𝔯)φ(𝔯)N𝔯2β0\displaystyle\frac{1}{s_{k}^{2}}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})}{\varphi({\mathfrak{r}})}+w^{2\beta_{0}-2}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}C_{{\mathfrak{r}},\beta_{0}}^{2}\frac{\mu_{k}^{2}({\mathfrak{r}})\varphi({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{2\beta_{0}}}
+O(Cβ02N𝔯wμk2(𝔯)φ(𝔯)N𝔯2σ1/22(𝔯)(log2wN𝔯)4)\displaystyle+O\left(C_{\beta_{0}}^{{}^{\prime}2}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})\varphi({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{2}}\sigma_{-1/2}^{2}({\mathfrak{r}})(\log\frac{2w}{{\mathrm{N}}{\mathfrak{r}}})^{-4}\right)
+wβ01skN𝔯wμk2(𝔯)N𝔯β0C𝔯,β0+O(Cβ0N𝔯wμk2(𝔯)σ1/2(𝔯)N𝔯(log2wN𝔯)2)\displaystyle+\frac{w^{\beta_{0}-1}}{s_{k}}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{\beta_{0}}}C_{{\mathfrak{r}},\beta_{0}}+O(C_{\beta_{0}}^{{}^{\prime}}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})\sigma_{-1/2}({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}}(\log\frac{2w}{{\mathrm{N}}{\mathfrak{r}}})^{-2})
+wβ01O(Cβ0N𝔯wμk2(𝔯)φ(𝔯)N𝔯1+β0|C𝔯,β0|σ1/2(𝔯)(log2wN𝔯)2.\displaystyle+w^{\beta_{0}-1}O(C_{\beta_{0}}^{{}^{\prime}}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})\varphi({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{1+\beta_{0}}}|C_{{\mathfrak{r}},\beta_{0}}|\sigma_{-1/2}({\mathfrak{r}})(\log\frac{2w}{{\mathrm{N}}{\mathfrak{r}}})^{-2}.

The term involving β0{\beta_{0}} exists if and only if the Siegel zero exists (and similarly for the proofs below).

Among the six terms in (4.4), we apply Lemma 3.5 to the first term to obtain

(4.5) 1sk2N𝔯wμk2(𝔯)φ(𝔯)=1sklogw+O(1).\frac{1}{s_{k}^{2}}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\mu_{k}^{2}({\mathfrak{r}})}{\varphi({\mathfrak{r}})}=\frac{1}{s_{k}}\log w+O(1).

For the second term, we have

(4.6) |w2β02N𝔯wC𝔯,β02μk2(𝔯)φ(𝔯)N𝔯2β0|\displaystyle\left|w^{2\beta_{0}-2}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}C_{{\mathfrak{r}},\beta_{0}}^{2}\frac{\mu_{k}^{2}({\mathfrak{r}})\varphi({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{2\beta_{0}}}\right| \displaystyle\leq w2β02N𝔯wC𝔯,β02N𝔯2β01w2β02Cβ02N𝔯wσ122(𝔯)N𝔯2β01\displaystyle w^{2\beta_{0}-2}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{C_{{\mathfrak{r}},\beta_{0}}^{2}}{{\mathrm{N}}{\mathfrak{r}}^{2\beta_{0}-1}}\leq w^{2\beta_{0}-2}C_{\beta_{0}}^{{}^{\prime}2}\sum_{{\mathrm{N}}{\mathfrak{r}}\leq w}\frac{\sigma_{-\frac{1}{2}}^{2}({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}^{2\beta_{0}-1}}
\displaystyle\ll Cβ021β0,\displaystyle\frac{C_{\beta_{0}}^{{}^{\prime}2}}{1-\beta_{0}},

where Cβ0C_{\beta_{0}}^{{}^{\prime}} is defined before Lemma 3.10 and the last step uses partial summation and Lemma 3.3.

We apply Lemma 3.4 to the third, fifth, and sixth term in (4.4). For the fourth term, we apply partial summation and Lemma 3.3. Then we can see that the third and fifth terms are O(Cβ02)O(C_{\beta_{0}}^{{}^{\prime}2}), and the fourth and sixth terms are O(Cβ021β0)O(\frac{C_{\beta_{0}}^{{}^{\prime}2}}{1-\beta_{0}}). Therefore,

(4.7) 𝔡,𝔢Λ1(𝔡)Λ2(𝔢)N([𝔡,𝔢])\displaystyle\sum_{{\mathfrak{d}},{\mathfrak{e}}}\frac{\Lambda_{1}({\mathfrak{d}})\Lambda_{2}({\mathfrak{e}})}{{\mathrm{N}}([{\mathfrak{d}},{\mathfrak{e}}])} =\displaystyle= 1sklogw+O(Cβ021β0)\displaystyle\frac{1}{s_{k}}\log w+O(\frac{C_{\beta_{0}}^{{}^{\prime}2}}{1-\beta_{0}})
=\displaystyle= 1sklogw+O(max{11β0,1(1β0)5|ζk(β0)|2}).\displaystyle\frac{1}{s_{k}}\log w+O(\max\{\frac{1}{1-\beta_{0}},\frac{1}{(1-\beta_{0})^{5}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|^{2}}\}).

Combining (4.3) and (4.7) in (4.2), we obtain Theorem 1.3 in the case wyxwy\leq x.

5. Proof of Theorem 1.3 in the case wy>xwy>x

Recall the definition of the von Mangoldt function for ideals in Section 2. We have the following identity. For an ideal 𝔫{\mathfrak{n}},

(5.1) 𝔡|𝔫μk(𝔡)log(zN𝔡)={Λ(𝔫) if 𝔫(1),logz if 𝔫=(1).\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\mu_{k}({\mathfrak{d}})\log(\frac{z}{{\mathrm{N}}{\mathfrak{d}}})=\begin{cases}\Lambda({\mathfrak{n}})&\text{ if }{\mathfrak{n}}\neq(1),\\ \log z&\text{ if }{\mathfrak{n}}=(1).\end{cases}

Using the equation above, we have for 𝔫(1){\mathfrak{n}}\neq(1),

𝔡|𝔫Λ1(𝔡)=Λ(𝔫)𝔡|𝔫N𝔡>wμk(𝔡)log(wN𝔡)=Λ(𝔫)+𝔡|𝔫N𝔡<N𝔫wμk(𝔫𝔡)log(N𝔫N𝔡w),\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\Lambda_{1}({\mathfrak{d}})=\Lambda({\mathfrak{n}})-\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}>w\end{subarray}}\mu_{k}({\mathfrak{d}})\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})=\Lambda({\mathfrak{n}})+\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{w}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{d}}w}),
𝔢|𝔫Λ2(𝔢)=Λ(𝔫)𝔢|𝔫N𝔢>yμk(𝔢)log(yN𝔢)=Λ(𝔫)+𝔢|𝔫N𝔢<N𝔫yμk(𝔫𝔢)log(N𝔫N𝔢y).\sum_{{\mathfrak{e}}|{\mathfrak{n}}}\Lambda_{2}({\mathfrak{e}})=\Lambda({\mathfrak{n}})-\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}>y\end{subarray}}\mu_{k}({\mathfrak{e}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{e}}})=\Lambda({\mathfrak{n}})+\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{y}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{e}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{e}}y}).

Now we compute the left-hand side of Theorem 1.3. We separate the terms N𝔫=1{\mathrm{N}}{\mathfrak{n}}=1 and 1<N𝔫x1<{\mathrm{N}}{\mathfrak{n}}\leq x and obtain

N𝔫x(𝔡|𝔫Λ1(𝔡))(𝔢|𝔫Λ2(𝔢))\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\Lambda_{1}({\mathfrak{d}})\right)\left(\sum_{{\mathfrak{e}}|{\mathfrak{n}}}\Lambda_{2}({\mathfrak{e}})\right)
=\displaystyle= logwlogy\displaystyle\log w\log y
+1<N𝔫x(Λ(𝔫)+𝔡|𝔫N𝔡<N𝔫wμk(𝔫𝔡)log(N𝔫N𝔡w))(Λ(𝔫)+𝔢|𝔫N𝔢<N𝔫yμk(𝔫𝔢)log(N𝔫N𝔢y))\displaystyle+\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\Lambda({\mathfrak{n}})+\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{w}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{d}}w})\right)\left(\Lambda({\mathfrak{n}})+\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{y}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{e}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{e}}y})\right)
=\displaystyle= logwlogy+1<N𝔫xΛ(𝔫)2\displaystyle\log w\log y+\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\Lambda({\mathfrak{n}})^{2}
+1<N𝔫xΛ(𝔫)[𝔡|𝔫N𝔡<N𝔫wμk(𝔫𝔡)log(N𝔫N𝔡w)+𝔢|𝔫N𝔢<N𝔫yμk(𝔫𝔢)log(N𝔫N𝔢y)]\displaystyle+\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\Lambda({\mathfrak{n}})\left[\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{w}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{d}}w})+\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{y}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{e}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{e}}y})\right]
+1<N𝔫x(𝔡|𝔫N𝔡<N𝔫wμk(𝔫𝔡)log(N𝔫N𝔡w))(𝔢|𝔫N𝔢<N𝔫yμk(𝔫𝔢)log(N𝔫N𝔢y))\displaystyle+\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{w}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{d}}w})\right)\left(\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{y}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{e}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{e}}y})\right)
=:\displaystyle=: logwlogy+S1+S2+S3.\displaystyle\log w\log y+S_{1}+S_{2}+S_{3}.

First, we discuss S1S_{1}. From the proof of the effective Chebotarev density theorem, or see e.g., [Mit68, Lemma 12], for any A2A\geq 2,

N𝔭QlogN𝔭=Q+OA(Q(log2Q)A).\sum_{{\mathrm{N}}{\mathfrak{p}}\leq Q}\log{\mathrm{N}}{\mathfrak{p}}=Q+O_{A}(Q(\log 2Q)^{-A}).

Then by partial summation,

S1=1<N𝔫xΛ(𝔫)2\displaystyle S_{1}=\sum_{1<{\mathrm{N}}{\mathfrak{n}}\leq x}\Lambda({\mathfrak{n}})^{2} =\displaystyle= N𝔭x(logN𝔭)2+O(x)\displaystyle\sum_{{\mathrm{N}}{\mathfrak{p}}\leq x}(\log{\mathrm{N}}{\mathfrak{p}})^{2}+O(x)
=\displaystyle= logxN𝔭xlogN𝔭N𝔭xlogN𝔭(logxlogN𝔭)\displaystyle\log x\sum_{{\mathrm{N}}{\mathfrak{p}}\leq x}\log{\mathrm{N}}{\mathfrak{p}}-\sum_{{\mathrm{N}}{\mathfrak{p}}\leq x}\log{\mathrm{N}}{\mathfrak{p}}(\log x-\log{\mathrm{N}}{\mathfrak{p}})
=\displaystyle= xlogx+O(x)+1x1tN𝔭tlogN𝔭dt\displaystyle x\log x+O(x)+\int_{1}^{x}\frac{1}{t}\sum_{{\mathrm{N}}{\mathfrak{p}}\leq t}\log{\mathrm{N}}{\mathfrak{p}}dt
=\displaystyle= xlogx+O(x).\displaystyle x\log x+O(x).

Next, we consider S2S_{2}. We write 𝔫=𝔭m{\mathfrak{n}}={\mathfrak{p}}^{m}. Then

𝔡|𝔫N𝔡<N𝔫wμk(𝔫𝔡)log(N𝔫N𝔡w)={log(N𝔭w) if w<N𝔭,0 otherwise.\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}<\frac{{\mathrm{N}}{\mathfrak{n}}}{w}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{d}}w})=\begin{cases}-\log(\frac{{\mathrm{N}}{\mathfrak{p}}}{w})&\text{ if }w<{\mathrm{N}}{\mathfrak{p}},\\ 0&\text{ otherwise.}\end{cases}

Thus,

S2=w<N𝔭x(logN𝔭)(logN𝔭w)y<N𝔭x(logN𝔭)(logN𝔭y)+O(x).S_{2}=-\sum_{w<{\mathrm{N}}{\mathfrak{p}}\leq x}(\log{\mathrm{N}}{\mathfrak{p}})(\log\frac{{\mathrm{N}}{\mathfrak{p}}}{w})-\sum_{y<{\mathrm{N}}{\mathfrak{p}}\leq x}(\log{\mathrm{N}}{\mathfrak{p}})(\log\frac{{\mathrm{N}}{\mathfrak{p}}}{y})+O(x).

Using partial summation, we have

w<N𝔭x(logN𝔭)(logN𝔭w)=xlog(xw)+O(x)\sum_{w<{\mathrm{N}}{\mathfrak{p}}\leq x}(\log{\mathrm{N}}{\mathfrak{p}})(\log\frac{{\mathrm{N}}{\mathfrak{p}}}{w})=x\log(\frac{x}{w})+O(x)

and

y<N𝔭x(logN𝔭)(logN𝔭y)=xlog(xy)+O(x).\sum_{y<{\mathrm{N}}{\mathfrak{p}}\leq x}(\log{\mathrm{N}}{\mathfrak{p}})(\log\frac{{\mathrm{N}}{\mathfrak{p}}}{y})=x\log(\frac{x}{y})+O(x).

Therefore,

S2=xlog(wyx2)+O(x).S_{2}=x\log(\frac{wy}{x^{2}})+O(x).

For S3S_{3}, we let (𝔡,𝔢)=𝔮,𝔡=𝔮𝔯,𝔢=𝔮𝔱({\mathfrak{d}},{\mathfrak{e}})={\mathfrak{q}},{\mathfrak{d}}={\mathfrak{q}}{\mathfrak{r}},{\mathfrak{e}}={\mathfrak{q}}{\mathfrak{t}} (so (𝔯,𝔱)=(1)({\mathfrak{r}},{\mathfrak{t}})=(1)), and let 𝔫=𝔪𝔮𝔯𝔱{\mathfrak{n}}={\mathfrak{m}}{\mathfrak{q}}{\mathfrak{r}}{\mathfrak{t}}. Then

S3\displaystyle S_{3} =\displaystyle= 𝔡N𝔡xw𝔢N𝔢xy𝔫N𝔡w<N𝔫xN𝔢y<N𝔫x[𝔡,𝔢]|𝔫μk(𝔫𝔡)μk(𝔫𝔢)log(N𝔫N𝔡w)log(N𝔫N𝔢y)\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}}\\ {\mathrm{N}}{\mathfrak{d}}\leq\frac{x}{w}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{e}}\\ {\mathrm{N}}{\mathfrak{e}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}w<{\mathrm{N}}{\mathfrak{n}}\leq x\\ {\mathrm{N}}{\mathfrak{e}}y<{\mathrm{N}}{\mathfrak{n}}\leq x\\ [{\mathfrak{d}},{\mathfrak{e}}]|{\mathfrak{n}}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{e}}})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{d}}w})\log(\frac{{\mathrm{N}}{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{e}}y})
=\displaystyle= 𝔮N𝔮xy𝔱N𝔱xN𝔮yμk(𝔱)𝔯N𝔯xN𝔮w(𝔯,𝔱)=(1)μk(𝔯)𝔪N𝔪xN𝔮N𝔯N𝔱N𝔪>wN𝔱,N𝔪>yN𝔯(𝔪,𝔯𝔱)=(1)μk2(𝔪)log(N𝔪N𝔱w)log(N𝔪N𝔯y).\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\mu_{k}({\mathfrak{t}})\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\\ ({\mathfrak{r}},{\mathfrak{t}})=(1)\end{subarray}}\mu_{k}({\mathfrak{r}})\sum_{\begin{subarray}{c}{\mathfrak{m}}\\ {\mathrm{N}}{\mathfrak{m}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}}\\ {\mathrm{N}}{\mathfrak{m}}>\frac{w}{{\mathrm{N}}{\mathfrak{t}}},{\mathrm{N}}{\mathfrak{m}}>\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\\ ({\mathfrak{m}},{\mathfrak{r}}{\mathfrak{t}})=(1)\end{subarray}}\mu_{k}^{2}({\mathfrak{m}})\log(\frac{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{t}}}{w})\log(\frac{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{r}}}{y}).

For the innermost sum, we rewrite the summation as

𝔪N𝔪xN𝔮N𝔯N𝔱N𝔪>wN𝔱,N𝔪>yN𝔯(𝔪,𝔯𝔱)=(1)=𝔪N𝔪xN𝔮N𝔯N𝔱(𝔪,𝔯𝔱)=(1)𝔪N𝔪max{wN𝔱,yN𝔯}(𝔪,𝔯𝔱)=(1)\sum_{\begin{subarray}{c}{\mathfrak{m}}\\ {\mathrm{N}}{\mathfrak{m}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}}\\ {\mathrm{N}}{\mathfrak{m}}>\frac{w}{{\mathrm{N}}{\mathfrak{t}}},{\mathrm{N}}{\mathfrak{m}}>\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\\ ({\mathfrak{m}},{\mathfrak{r}}{\mathfrak{t}})=(1)\end{subarray}}=\sum_{\begin{subarray}{c}{\mathfrak{m}}\\ {\mathrm{N}}{\mathfrak{m}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}}\\ ({\mathfrak{m}},{\mathfrak{r}}{\mathfrak{t}})=(1)\end{subarray}}-\sum_{\begin{subarray}{c}{\mathfrak{m}}\\ {\mathrm{N}}{\mathfrak{m}}\leq\max\{\frac{w}{{\mathrm{N}}{\mathfrak{t}}},\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\}\\ ({\mathfrak{m}},{\mathfrak{r}}{\mathfrak{t}})=(1)\end{subarray}}

so we need to compute, for M>1M>1, the sum

𝔪N𝔪M(𝔪,𝔯𝔱)=(1)μk2(𝔪)log(N𝔪N𝔱w)log(N𝔪N𝔯y).\sum_{\begin{subarray}{c}{\mathfrak{m}}\\ {\mathrm{N}}{\mathfrak{m}}\leq M\\ ({\mathfrak{m}},{\mathfrak{r}}{\mathfrak{t}})=(1)\end{subarray}}\mu_{k}^{2}({\mathfrak{m}})\log(\frac{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{t}}}{w})\log(\frac{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{r}}}{y}).

We apply partial summation twice and apply Lemma 3.7. We see that the sum is equal to

skζk(2)N𝔯N𝔱κ(𝔯)κ(𝔱)M((log(MN𝔱w)1)(log(MN𝔯y)1)+1)\displaystyle\frac{s_{k}}{\zeta_{k}(2)}\frac{{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}}{\kappa({\mathfrak{r}})\kappa({\mathfrak{t}})}M\left((\log(\frac{M{\mathrm{N}}{\mathfrak{t}}}{w})-1)(\log(\frac{M{\mathrm{N}}{\mathfrak{r}}}{y})-1)+1\right)
+\displaystyle+ O(log(2MN𝔱w)log(2MN𝔯y)M11nk+εkσ1nk+1(𝔯𝔱)).\displaystyle O\left(\log(\frac{2M{\mathrm{N}}{\mathfrak{t}}}{w})\log(\frac{2M{\mathrm{N}}{\mathfrak{r}}}{y})M^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}}{\mathfrak{t}})\right).

Thus, the innermost sum in (5) is equal to

skζk(2)xN𝔮κ(𝔯)κ(𝔱)((log(xN𝔮N𝔯w)1)(log(xN𝔮N𝔱y)1)+1)\displaystyle\frac{s_{k}}{\zeta_{k}(2)}\frac{x}{{\mathrm{N}}{\mathfrak{q}}\kappa({\mathfrak{r}})\kappa({\mathfrak{t}})}\left((\log(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})-1)(\log(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})-1)+1\right)
+\displaystyle+ skζk(2)max{wN𝔱,yN𝔯}N𝔯N𝔱κ(𝔯)κ(𝔱)(log(max{wN𝔱,yN𝔯}min{wN𝔱,yN𝔯})2)\displaystyle\frac{s_{k}}{\zeta_{k}(2)}\frac{\max\{\frac{w}{{\mathrm{N}}{\mathfrak{t}}},\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\}{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}}{\kappa({\mathfrak{r}})\kappa({\mathfrak{t}})}(\log(\frac{\max\{\frac{w}{{\mathrm{N}}{\mathfrak{t}}},\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\}}{\min\{\frac{w}{{\mathrm{N}}{\mathfrak{t}}},\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\}})-2)
+\displaystyle+ O(log(2xN𝔮N𝔯w)log(2xN𝔮N𝔱y)(xN𝔮N𝔯N𝔱)11nk+εkσ1nk+1(𝔯𝔱)).\displaystyle O\left(\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}})^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}}{\mathfrak{t}})\right).

Plugging this into (5), we have

S3\displaystyle S_{3} =\displaystyle= skζk(2)x𝔮N𝔮xy1N𝔮𝔱N𝔱xN𝔮yμk(𝔱)κ(𝔱)𝔯N𝔯xN𝔮w(𝔯,𝔱)=(1)μk(𝔯)κ(𝔯)((log(xN𝔮N𝔯w)1)(log(xN𝔮N𝔱y)1)+1)\displaystyle\frac{s_{k}}{\zeta_{k}(2)}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{\mu_{k}({\mathfrak{t}})}{\kappa({\mathfrak{t}})}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\\ ({\mathfrak{r}},{\mathfrak{t}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{r}})}{\kappa({\mathfrak{r}})}\left((\log(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})-1)(\log(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})-1)+1\right)
+skζk(2)𝔮N𝔮xy𝔯N𝔯xN𝔮wμk(𝔯)N𝔯κ(𝔯)𝔱N𝔱wN𝔯y(𝔱,𝔯)=(1)wN𝔱μk(𝔱)N𝔱κ(𝔱)(log(wN𝔯yN𝔱)2)\displaystyle+\frac{s_{k}}{\zeta_{k}(2)}\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\end{subarray}}\frac{\mu_{k}({\mathfrak{r}}){\mathrm{N}}{\mathfrak{r}}}{\kappa({\mathfrak{r}})}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{w{\mathrm{N}}{\mathfrak{r}}}{y}\\ ({\mathfrak{t}},{\mathfrak{r}})=(1)\end{subarray}}\frac{w}{{\mathrm{N}}{\mathfrak{t}}}\cdot\frac{\mu_{k}({\mathfrak{t}}){\mathrm{N}}{\mathfrak{t}}}{\kappa({\mathfrak{t}})}\left(\log(\frac{w{\mathrm{N}}{\mathfrak{r}}}{y{\mathrm{N}}{\mathfrak{t}}})-2\right)
+skζk(2)𝔮N𝔮xy𝔱N𝔱xN𝔮yμk(𝔱)N𝔱κ(𝔱)𝔯N𝔯yN𝔱w(𝔯,𝔱)=(1)yN𝔯μk(𝔯)N𝔯κ(𝔯)(log(yN𝔱wN𝔯)2)\displaystyle+\frac{s_{k}}{\zeta_{k}(2)}\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{\mu_{k}({\mathfrak{t}}){\mathrm{N}}{\mathfrak{t}}}{\kappa({\mathfrak{t}})}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{y{\mathrm{N}}{\mathfrak{t}}}{w}\\ ({\mathfrak{r}},{\mathfrak{t}})=(1)\end{subarray}}\frac{y}{{\mathrm{N}}{\mathfrak{r}}}\cdot\frac{\mu_{k}({\mathfrak{r}}){\mathrm{N}}{\mathfrak{r}}}{\kappa({\mathfrak{r}})}\left(\log(\frac{y{\mathrm{N}}{\mathfrak{t}}}{w{\mathrm{N}}{\mathfrak{r}}})-2\right)
+O(𝔮N𝔮xy𝔱N𝔱xN𝔮y𝔯N𝔯xN𝔮w(𝔯,𝔱)=(1)log(2xN𝔮N𝔯w)log(2xN𝔮N𝔱y)(xN𝔮N𝔯N𝔱)11nk+εkσ1nk+1(𝔯𝔱))\displaystyle+O\left(\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\\ ({\mathfrak{r}},{\mathfrak{t}})=(1)\end{subarray}}\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}{\mathrm{N}}{\mathfrak{t}}})^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}}{\mathfrak{t}})\right)
=:\displaystyle=: ΣA+ΣB+ΣC+O(ΣD).\displaystyle\Sigma_{A}+\Sigma_{B}+\Sigma_{C}+O(\Sigma_{D}).

First, we consider ΣA\Sigma_{A} as follows. By Lemmas 3.11 and 3.12, we have

𝔯N𝔯xN𝔮w(𝔯,𝔱)=(1)μk(𝔯)κ(𝔯)((log(xN𝔮N𝔯w)1)(log(xN𝔮N𝔱y)1)+1)\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\\ ({\mathfrak{r}},{\mathfrak{t}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{r}})}{\kappa({\mathfrak{r}})}\left((\log(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})-1)(\log(\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})-1)+1\right)
=\displaystyle= (logxN𝔮N𝔱y1)[κ(𝔱)N𝔱ζk(2)sk+C𝔱,β0(xN𝔮w)β01+O(Cβ0σ12(𝔱)(log2xN𝔮w)4)]\displaystyle(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1)\left[\frac{\kappa({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}\frac{\zeta_{k}(2)}{s_{k}}+C_{{\mathfrak{t}},\beta_{0}}^{{}^{\prime}}(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1}+O(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-4})\right]
(logxN𝔮N𝔱y1)[O(C𝔱,β0(1β0)(xN𝔮w)β01+Cβ0σ12(𝔱)(log2xN𝔮w)4)]\displaystyle-(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1)\left[O(C_{{\mathfrak{t}},\beta_{0}}^{{}^{\prime}}(1-\beta_{0})(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1}+C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-4})\right]
+O(C𝔱,β0(1β0)(xN𝔮w)β01+Cβ0σ12(𝔱)(log2xN𝔮w)4)\displaystyle+O(C_{{\mathfrak{t}},\beta_{0}}^{{}^{\prime}}(1-\beta_{0})(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1}+C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-4})
=\displaystyle= (logxN𝔮N𝔱y1)[κ(𝔱)N𝔱ζk(2)sk+O(Cβ0σ12(𝔱)(xN𝔮w)β01)+O(Cβ0σ12(𝔱)(log2xN𝔮w)4)].\displaystyle(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1)\left[\frac{\kappa({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}\frac{\zeta_{k}(2)}{s_{k}}+O(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1})+O(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-4})\right].

Plugging this into ΣA\Sigma_{A}, we get

ΣA\displaystyle\Sigma_{A} =\displaystyle= skζk(2)x𝔮N𝔮xy1N𝔮𝔱N𝔱xN𝔮yμk(𝔱)κ(𝔱)(κ(𝔱)N𝔱ζk(2)sklogxN𝔮N𝔱yκ(𝔱)N𝔱ζk(2)sk)\displaystyle\frac{s_{k}}{\zeta_{k}(2)}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{\mu_{k}({\mathfrak{t}})}{\kappa({\mathfrak{t}})}\left(\frac{\kappa({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}\frac{\zeta_{k}(2)}{s_{k}}\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-\frac{\kappa({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}\frac{\zeta_{k}(2)}{s_{k}}\right)
+skζk(2)x𝔮N𝔮xy1N𝔮(xN𝔮w)β01O(Cβ0𝔱N𝔱xN𝔮yσ12(𝔱)|logxN𝔮N𝔱y1|N𝔱)\displaystyle+\frac{s_{k}}{\zeta_{k}(2)}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1}O\left(C_{\beta_{0}}^{{}^{\prime}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})\frac{|\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1|}{{\mathrm{N}}{\mathfrak{t}}}\right)
+skζk(2)x𝔮N𝔮xy1N𝔮(log2xN𝔮w)4O(Cβ0𝔱N𝔱xN𝔮y|logxN𝔮N𝔱y1|N𝔱σ12(𝔱))\displaystyle+\frac{s_{k}}{\zeta_{k}(2)}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-4}O\left(C_{\beta_{0}}^{{}^{\prime}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{|\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1|}{{\mathrm{N}}{\mathfrak{t}}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})\right)
=\displaystyle= x𝔮N𝔮xy1N𝔮𝔱N𝔱xN𝔮yμk(𝔱)N𝔱(logxN𝔮N𝔱y1)\displaystyle x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{\mu_{k}({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1)
+O(Cβ0x𝔮N𝔮xy1N𝔮(logxN𝔮y)(xN𝔮w)β01𝔱N𝔱xN𝔮y1N𝔱σ12(𝔱))\displaystyle+O\left(C_{\beta_{0}}^{{}^{\prime}}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}y})(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{t}}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})\right)
+O(Cβ0x𝔮N𝔮xy1N𝔮(log2xN𝔮w)3𝔱N𝔱xN𝔮y1N𝔱σ12(𝔱)).\displaystyle+O\left(C_{\beta_{0}}^{{}^{\prime}}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-3}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{t}}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})\right).

Applying (3.2) and (3.3) to the inner sum of the first term in (5), we have

𝔱N𝔱xN𝔮yμk(𝔱)N𝔱(logxN𝔮N𝔱y1)\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{\mu_{k}({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y}-1)
=\displaystyle= (logxN𝔮y1)[(xN𝔮y)β01(β01)ζk(β0)+O((log2xN𝔮y)3)]\displaystyle(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}-1)\left[\frac{(\frac{x}{{\mathrm{N}}{\mathfrak{q}}y})^{\beta_{0}-1}}{(\beta_{0}-1)\zeta_{k}^{{}^{\prime}}(\beta_{0})}+O((\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y})^{-3})\right]
[1sk+(xN𝔮y)β01((β01)logxN𝔮y1)(β01)2ζk(β0)+O((log2xN𝔮y)2)]\displaystyle-\left[-\frac{1}{s_{k}}+\frac{(\frac{x}{{\mathrm{N}}{\mathfrak{q}}y})^{\beta_{0}-1}((\beta_{0}-1)\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}-1)}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}+O((\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y})^{-2})\right]
=\displaystyle= 1sk+(xN𝔮y)β01(β01)2ζk(β0)(2β0)+O((log2xN𝔮y)2).\displaystyle\frac{1}{s_{k}}+\frac{(\frac{x}{{\mathrm{N}}{\mathfrak{q}}y})^{\beta_{0}-1}}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}(2-\beta_{0})+O((\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y})^{-2}).

Thus, by Lemma 3.1 (in the cases a=1a=1 and a=β0a=\beta_{0}) and Lemma 3.4, the first term in (5) satisfies

x𝔮N𝔮xy1N𝔮𝔱N𝔱xN𝔮yμk(𝔱)N𝔱(log(xN𝔱N𝔮y)1)=xlogxy+O(1(1β0)3|ζk(β0)|x).x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{\mu_{k}({\mathfrak{t}})}{{\mathrm{N}}{\mathfrak{t}}}(\log(\frac{x}{{\mathrm{N}}{\mathfrak{t}}{\mathrm{N}}{\mathfrak{q}}y})-1)=x\log\frac{x}{y}+O(\frac{1}{(1-\beta_{0})^{3}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}x).

Next, we consider the second term in (5). Note that for any positive integer AA and positive number aa, we have

(5.4) (β01)a+AlogaAlogA1β0.(\beta_{0}-1)a+A\log a\leq A\log\frac{A}{1-\beta_{0}}.

Then for any 𝔮{\mathfrak{q}}, we apply (5.4) with A=4,a=logxN𝔮wA=4,a=\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}w} and obtain (xN𝔮w)β011(1β0)4(logxN𝔮w)41(1β0)4(logxN𝔮y)4(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}-1}\ll\frac{1}{(1-\beta_{0})^{4}}(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{-4}\ll\frac{1}{(1-\beta_{0})^{4}}(\log\frac{x}{{\mathrm{N}}{\mathfrak{q}}y})^{-4}. Then we can consider the second term and the third term in (5) together as

O(Cβ0(1β0)4x𝔮N𝔮xy1N𝔮(log2xN𝔮w)3𝔱N𝔱xN𝔮y1N𝔱σ12(𝔱)).O\left(\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{4}}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-3}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{t}}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})\right).

Applying partial summation and Lemma 3.3 on the innermost sum of this term, we have

𝔱N𝔱xN𝔮y1N𝔱σ12(𝔱)log2xN𝔮ylog2xN𝔮w.\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{t}}}\sigma_{-\frac{1}{2}}({\mathfrak{t}})\ll\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y}\leq\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w}.

Thus, by Lemma 3.4, the second and the third terms in (5) are O(Cβ0(1β0)4x)O(\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{4}}x).

Combining all the estimates for the terms in (5), we have

ΣA=xlogxy+O((1(1β0)3|ζk(β0)|+Cβ0(1β0)4)x).\Sigma_{A}=x\log\frac{x}{y}+O\left((\frac{1}{(1-\beta_{0})^{3}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}+\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{4}})x\right).

Second, we consider ΣB\Sigma_{B} and ΣC\Sigma_{C}. Our approach is essentially the same as that in estimating ΣA\Sigma_{A}. By Lemmas 3.11 and 3.12, we have

𝔱N𝔱wN𝔯y(𝔱,𝔯)=(1)μk(𝔱)κ(𝔱)(logwN𝔯yN𝔱2)\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{w{\mathrm{N}}{\mathfrak{r}}}{y}\\ ({\mathfrak{t}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{t}})}{\kappa({\mathfrak{t}})}(\log\frac{w{\mathrm{N}}{\mathfrak{r}}}{y{\mathrm{N}}{\mathfrak{t}}}-2)
=\displaystyle= (κ(𝔯)N𝔯ζk(2)sk+C𝔯,β0(wN𝔯y)β01+O(Cβ0σ12(𝔯)(log2wN𝔯y)2))\displaystyle\left(\frac{\kappa({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}}\frac{\zeta_{k}(2)}{s_{k}}+C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}(\frac{w{\mathrm{N}}{\mathfrak{r}}}{y})^{\beta_{0}-1}+O(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log\frac{2w{\mathrm{N}}{\mathfrak{r}}}{y})^{-2})\right)
+O(|C𝔯,β0|(1β0)(wN𝔯y)β01+Cβ0σ12(𝔯)(log2wN𝔯y)2).\displaystyle+O\left(|C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}|(1-\beta_{0})(\frac{w{\mathrm{N}}{\mathfrak{r}}}{y})^{\beta_{0}-1}+C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log\frac{2w{\mathrm{N}}{\mathfrak{r}}}{y})^{-2}\right).

Plugging this into ΣB\Sigma_{B}, we get

(5.5) ΣB\displaystyle\Sigma_{B} =\displaystyle= w𝔮N𝔮xy𝔯ywN𝔯xN𝔮wμk(𝔯)+O(Cβ0w𝔮N𝔮xy𝔯ywN𝔯xN𝔮w(wN𝔯y)β01σ12(𝔯))\displaystyle w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ \frac{y}{w}\leq{\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\end{subarray}}\mu_{k}({\mathfrak{r}})+O\left(C_{\beta_{0}}^{{}^{\prime}}w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ \frac{y}{w}\leq{\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\end{subarray}}(\frac{w{\mathrm{N}}{\mathfrak{r}}}{y})^{\beta_{0}-1}\sigma_{-\frac{1}{2}}({\mathfrak{r}})\right)
+O(Cβ0w𝔮N𝔮xy𝔯ywN𝔯xN𝔮wσ12(𝔯)(log2wN𝔯y)2).\displaystyle+O\left(C_{\beta_{0}}^{{}^{\prime}}w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ \frac{y}{w}\leq{\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\end{subarray}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log\frac{2w{\mathrm{N}}{\mathfrak{r}}}{y})^{-2}\right).

By (3.1), Lemma 3.1, and Lemma 3.4, the first term in (5.5) is bounded by

\displaystyle\ll w𝔮N𝔮xy(xN𝔮w)β0β0|ζk(β0)|+w𝔮N𝔮xyxN𝔮w(log2xN𝔮w)2\displaystyle w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\beta_{0}}}{\beta_{0}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}+w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}w})^{-2}
\displaystyle\ll w(xw)β0(xy)1β0(1β0)|ζk(β0)|+x𝔮N𝔮xy1N𝔮(log2xN𝔮y)2x(1β0)|ζk(β0)|.\displaystyle\frac{w(\frac{x}{w})^{\beta_{0}}(\frac{x}{y})^{1-\beta_{0}}}{(1-\beta_{0})|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}+x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y})^{-2}\ll\frac{x}{(1-\beta_{0})|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}.

By (5.4) with A=2,a=log2wN𝔯yA=2,a=\log\frac{2w{\mathrm{N}}{\mathfrak{r}}}{y}, we have (wN𝔯y)β011(1β0)2(log2wN𝔯y)2(\frac{w{\mathrm{N}}{\mathfrak{r}}}{y})^{\beta_{0}-1}\ll\frac{1}{(1-\beta_{0})^{2}}(\log\frac{2w{\mathrm{N}}{\mathfrak{r}}}{y})^{-2}. Thus, the two error terms in (5.5) can be combined as

O(Cβ0(1β0)2w𝔮N𝔮xy𝔯ywN𝔯xN𝔮wσ12(𝔯)(log2wN𝔯y)2).O\left(\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{2}}w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ \frac{y}{w}\leq{\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\end{subarray}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log\frac{2w{\mathrm{N}}{\mathfrak{r}}}{y})^{-2}\right).

By partial summation, Lemma 3.3, and Lemma 3.4, this term is bounded by

Cβ0(1β0)2w𝔮N𝔮xyxN𝔮w(log2xN𝔮y)2Cβ0(1β0)2x𝔮N𝔮xy1N𝔮(log2xN𝔮y)2Cβ0(1β0)2x.\ll\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{2}}w\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y})^{-2}\ll\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{2}}x\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{q}}}(\log\frac{2x}{{\mathrm{N}}{\mathfrak{q}}y})^{-2}\ll\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{2}}x.

Thus,

ΣB=O((1(1β0)|ζk(β0)|+Cβ0(1β0)2)x).\Sigma_{B}=O\left((\frac{1}{(1-\beta_{0})|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}+\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{2}})x\right).

Similarly, ΣC=O((1(1β0)|ζk(β0)|+Cβ0(1β0)2)x)\Sigma_{C}=O\left((\frac{1}{(1-\beta_{0})|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}+\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{2}})x\right).

Third, we consider ΣD\Sigma_{D}. We write

ΣD\displaystyle\Sigma_{D} =\displaystyle= x11nk+εk𝔮N𝔮xyN𝔮1+1nkεk𝔱N𝔱xN𝔮yN𝔱1+1nkεklog(2xN𝔮N𝔱y)σ1nk+1(𝔱)\displaystyle x^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}{\mathrm{N}}{\mathfrak{q}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}{\mathrm{N}}{\mathfrak{t}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{t}})
×𝔯N𝔯xN𝔮w(𝔯,𝔱)=(1)N𝔯1+1nkεklog(2xN𝔮N𝔯w)σ1nk+1(𝔯)\displaystyle\times\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\\ ({\mathfrak{r}},{\mathfrak{t}})=(1)\end{subarray}}{\mathrm{N}}{\mathfrak{r}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}})
\displaystyle\ll x11nk+εk𝔮N𝔮xyN𝔮1+1nkεk𝔱N𝔱xN𝔮yN𝔱1+1nkεklog(2xN𝔮N𝔱y)σ1nk+1(𝔱)\displaystyle x^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}{\mathrm{N}}{\mathfrak{q}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\sum_{\begin{subarray}{c}{\mathfrak{t}}\\ {\mathrm{N}}{\mathfrak{t}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}y}\end{subarray}}{\mathrm{N}}{\mathfrak{t}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{t}}y})\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{t}})
×𝔯N𝔯xN𝔮wN𝔯1+1nkεklog(2xN𝔮N𝔯w)σ1nk+1(𝔯).\displaystyle\times\sum_{\begin{subarray}{c}{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{r}}\leq\frac{x}{{\mathrm{N}}{\mathfrak{q}}w}\end{subarray}}{\mathrm{N}}{\mathfrak{r}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\log(\frac{2x}{{\mathrm{N}}{\mathfrak{q}}{\mathrm{N}}{\mathfrak{r}}w})\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}}).

For the sum involving 𝔱{\mathfrak{t}} and 𝔯{\mathfrak{r}}, they have the same form, so we compute the following sum, for Q>1Q>1,

𝔡N𝔡QN𝔡1+1nkεklog(2QN𝔡)σ1nk+1(𝔡)\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}}\\ {\mathrm{N}}{\mathfrak{d}}\leq Q\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\log(\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{d}}) \displaystyle\ll k1k(Q2k)1+1nkεk𝔡Q2k<N𝔡2Q2kσ1nk+1(𝔡)\displaystyle\sum_{k\geq 1}k(\frac{Q}{2^{k}})^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\sum_{\begin{subarray}{c}{\mathfrak{d}}\\ \frac{Q}{2^{k}}<{\mathrm{N}}{\mathfrak{d}}\leq\frac{2Q}{2^{k}}\end{subarray}}\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{d}})
\displaystyle\ll k1k(Q2k)1nkεk\displaystyle\sum_{k\geq 1}k(\frac{Q}{2^{k}})^{\frac{1}{n_{k}}-{\varepsilon}_{k}}
\displaystyle\ll Q1nkεk.\displaystyle Q^{\frac{1}{n_{k}}-{\varepsilon}_{k}}.

Therefore,

ΣD\displaystyle\Sigma_{D} \displaystyle\ll x11nk+εk𝔮N𝔮xyN𝔮1+1nkεk(xN𝔮y)1nkεk(xN𝔮w)1nkεk\displaystyle x^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sum_{\begin{subarray}{c}{\mathfrak{q}}\\ {\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}\end{subarray}}{\mathrm{N}}{\mathfrak{q}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}\cdot(\frac{x}{{\mathrm{N}}{\mathfrak{q}}y})^{\frac{1}{n_{k}}-{\varepsilon}_{k}}\cdot(\frac{x}{{\mathrm{N}}{\mathfrak{q}}w})^{\frac{1}{n_{k}}-{\varepsilon}_{k}}
=\displaystyle= x1+1nkεk(wy)1nk+εkN𝔮xyN𝔮11nk+εkx1+1nkεk(wy)1nk+εk\displaystyle x^{1+\frac{1}{n_{k}}-{\varepsilon}_{k}}(wy)^{-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sum_{{\mathrm{N}}{\mathfrak{q}}\leq\frac{x}{y}}{\mathrm{N}}{\mathfrak{q}}^{-1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\ll x^{1+\frac{1}{n_{k}}-{\varepsilon}_{k}}(wy)^{-\frac{1}{n_{k}}+{\varepsilon}_{k}}
\displaystyle\ll x.\displaystyle x.

Combining our computations for ΣA,ΣB,ΣC,ΣD\Sigma_{A},\Sigma_{B},\Sigma_{C},\Sigma_{D}, we have

S3\displaystyle S_{3} =\displaystyle= xlogxy+O((1(1β0)3|ζk(β0)|+Cβ0(1β0)4)x)\displaystyle x\log\frac{x}{y}+O\left((\frac{1}{(1-\beta_{0})^{3}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}+\frac{C_{\beta_{0}}^{{}^{\prime}}}{(1-\beta_{0})^{4}})x\right)
=\displaystyle= xlogxy+O(max{1(1β0)4,1(1β0)6|ζk(β0)|}x).\displaystyle x\log\frac{x}{y}+O\left(\max\{\frac{1}{(1-\beta_{0})^{4}},\frac{1}{(1-\beta_{0})^{6}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}\}x\right).

Combining our computations for S1,S2,S3S_{1},S_{2},S_{3}, we obtain Theorem 1.3 in the case wy>xwy>x.

6. Proofs of lemmas and deductions

In this section, we do three things so that all of our proofs are complete. First, we prove Theorem 1.1 assuming Theorem 1.3. Second, we prove Corollary 1.2 assuming Theorem 1.1. Third, we prove all the lemmas stated in Section 3.

Proof of Theorem 1.1 assuming Theorem 1.3.

We compute

(log(yw))2N𝔫x(𝔡|𝔫λ𝔡)2\displaystyle(\log(\frac{y}{w}))^{2}\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\lambda_{\mathfrak{d}}\right)^{2} =\displaystyle= N𝔫x(𝔡|𝔫N𝔡yμk(𝔡)log(yN𝔡)𝔡|𝔫N𝔡wμk(𝔡)log(wN𝔡))2\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}\leq y\end{subarray}}\mu_{k}({\mathfrak{d}})\log(\frac{y}{{\mathrm{N}}{\mathfrak{d}}})-\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\end{subarray}}\mu_{k}({\mathfrak{d}})\log(\frac{w}{{\mathrm{N}}{\mathfrak{d}}})\right)^{2}
=\displaystyle= N𝔫x(𝔡|𝔫N𝔡wΛ1(𝔡))2+N𝔫x(𝔢|𝔫N𝔢yΛ2(𝔢))2\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\end{subarray}}\Lambda_{1}({\mathfrak{d}})\right)^{2}+\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\Lambda_{2}({\mathfrak{e}})\right)^{2}
2N𝔫x(𝔡|𝔫N𝔡wΛ1(𝔡))(𝔢|𝔫N𝔢yΛ2(𝔢)).\displaystyle-2\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\left(\sum_{\begin{subarray}{c}{\mathfrak{d}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{d}}\leq w\end{subarray}}\Lambda_{1}({\mathfrak{d}})\right)\left(\sum_{\begin{subarray}{c}{\mathfrak{e}}|{\mathfrak{n}}\\ {\mathrm{N}}{\mathfrak{e}}\leq y\end{subarray}}\Lambda_{2}({\mathfrak{e}})\right).

Applying Theorem 1.3 to each of the three terms, we obtain Theorem 1.1. ∎

Proof of Corollary 1.2 assuming Theorem 1.1.

Define

Δ(𝔫):=𝔡|𝔫λ𝔡.\Delta({\mathfrak{n}}):=\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\lambda_{\mathfrak{d}}.

We compute the left-hand side of the statement in Corollary 1.2. Note that it does not affect the result whether we start the sum from 1 or from ww because Δ(𝔫)=0\Delta({\mathfrak{n}})=0 if 1<𝔫<w1<{\mathfrak{n}}<w. Precisely:

N𝔫xΔ(𝔫)2N𝔫12α\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}{\mathrm{N}}{\mathfrak{n}}^{1-2\alpha} =\displaystyle= x12αN𝔫xΔ(𝔫)2N𝔫xΔ(𝔫)2(x12αN𝔫12α)\displaystyle x^{1-2\alpha}\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}-\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}(x^{1-2\alpha}-{\mathrm{N}}{\mathfrak{n}}^{1-2\alpha})
=\displaystyle= x12αN𝔫xΔ(𝔫)2N𝔫xΔ(𝔫)2N𝔫x(12α)t2α𝑑t+1\displaystyle x^{1-2\alpha}\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}-\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}\int_{{\mathrm{N}}{\mathfrak{n}}}^{x}(1-2\alpha)t^{-2\alpha}dt+1
=\displaystyle= x12αN𝔫xΔ(𝔫)2+(2α1)1xt2α(n=1tΔ(𝔫)2)𝑑t+1.\displaystyle x^{1-2\alpha}\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}+(2\alpha-1)\int_{1}^{x}t^{-2\alpha}\left(\sum_{n=1}^{t}\Delta({\mathfrak{n}})^{2}\right)dt+1.

Theorem 1.1 tells us that

N𝔫xΔ(𝔫)2=xlog(y/w)+O(Cβ0xlog2(y/w)).\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}=\frac{x}{\log(y/w)}+O(\frac{C_{\beta_{0}}x}{\log^{2}(y/w)}).

The constant associated to the error term may depend on nk,dkn_{k},d_{k}, and we omit the notations in this proof.

Thus,

N𝔫xΔ(𝔫)2N𝔫12α\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}{\mathrm{N}}{\mathfrak{n}}^{1-2\alpha} =\displaystyle= x22αlog(y/w)+(2α1)1xt2α(tlog(y/w))𝑑t+O(Cβ0x22αlog2(y/w))\displaystyle\frac{x^{2-2\alpha}}{\log(y/w)}+(2\alpha-1)\int_{1}^{x}t^{-2\alpha}\left(\frac{t}{\log(y/w)}\right)dt+O(\frac{C_{\beta_{0}}x^{2-2\alpha}}{\log^{2}(y/w)})
=\displaystyle= x22α22α1log(y/w)+O(Cβ0x22αlog2(y/w)).\displaystyle\frac{x^{2-2\alpha}}{2-2\alpha}\cdot\frac{1}{\log(y/w)}+O(\frac{C_{\beta_{0}}x^{2-2\alpha}}{\log^{2}(y/w)}).

Similarly,

N𝔫<wΔ(𝔫)2N𝔫12α=w22α22α1log(y/w)+O(Cβ0w22αlog2(y/w)).\sum_{{\mathrm{N}}{\mathfrak{n}}<w}\Delta({\mathfrak{n}})^{2}{\mathrm{N}}{\mathfrak{n}}^{1-2\alpha}=\frac{w^{2-2\alpha}}{2-2\alpha}\cdot\frac{1}{\log(y/w)}+O(\frac{C_{\beta_{0}}w^{2-2\alpha}}{\log^{2}(y/w)}).

Therefore,

wN𝔫xΔ(𝔫)2N𝔫12α\displaystyle\sum_{w\leq{\mathrm{N}}{\mathfrak{n}}\leq x}\Delta({\mathfrak{n}})^{2}{\mathrm{N}}{\mathfrak{n}}^{1-2\alpha} =\displaystyle= 1log(y/w)x22αw22α22α(1+O(Cβ0log(y/w))\displaystyle\frac{1}{\log(y/w)}\cdot\frac{x^{2-2\alpha}-w^{2-2\alpha}}{2-2\alpha}(1+O(\frac{C_{\beta_{0}}}{\log(y/w)})
\displaystyle\ll Cβ0log(y/w)x22αw22α22α\displaystyle\frac{C_{\beta_{0}}}{\log(y/w)}\cdot\frac{x^{2-2\alpha}-w^{2-2\alpha}}{2-2\alpha}

Since

x22αw22α22α=logwlogxe(22α)t𝑑tlog(x/w)x22α,\frac{x^{2-2\alpha}-w^{2-2\alpha}}{2-2\alpha}=\int_{\log w}^{\log x}e^{(2-2\alpha)t}dt\leq\log(x/w)x^{2-2\alpha},

this completes the proof of Corollary 1.2 assuming Theorem 1.1. ∎

Proof of Lemma 3.1.

Using partial summation and applying Theorem A, we write

N𝔫QN𝔫a\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\end{subarray}}{\mathrm{N}}{\mathfrak{n}}^{-a} =\displaystyle= QaN𝔫Q1N𝔫Q(QaN𝔫a)\displaystyle Q^{-a}\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\end{subarray}}1-\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\end{subarray}}(Q^{-a}-{\mathrm{N}}{\mathfrak{n}}^{-a})
=\displaystyle= skQ1aN𝔫QN𝔫Q(a)t1a𝑑t+O(Q11nka)\displaystyle s_{k}Q^{1-a}-\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\end{subarray}}\int_{{\mathrm{N}}{\mathfrak{n}}}^{Q}(-a)t^{-1-a}dt+O(Q^{1-\frac{1}{n_{k}}-a})
=\displaystyle= skQ1a+1Qat1aN𝔫t1dt+O(Q11nka)\displaystyle s_{k}Q^{1-a}+\int_{1}^{Q}at^{-1-a}\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq t\end{subarray}}1dt+O(Q^{1-\frac{1}{n_{k}}-a})
=\displaystyle= skQ1a+1Qaskta𝑑t+O(1Qat1nka𝑑t)+O(Q11nka).\displaystyle s_{k}Q^{1-a}+\int_{1}^{Q}as_{k}t^{-a}dt+O(\int_{1}^{Q}at^{-\frac{1}{n_{k}}-a}dt)+O(Q^{1-\frac{1}{n_{k}}-a}).

If 0<a<11nk0<a<1-\frac{1}{n_{k}} or 11nk<a<11-\frac{1}{n_{k}}<a<1, it is sk1aQ1a+O(Q11nka)+O(1).\frac{s_{k}}{1-a}Q^{1-a}+O(Q^{1-\frac{1}{n_{k}}-a})+O(1).

If a=11nka=1-\frac{1}{n_{k}}, it is sknkQ1nk+O(logQ).s_{k}n_{k}Q^{\frac{1}{n_{k}}}+O(\log Q).

If a=1a=1, it is sklogQ+O(1).s_{k}\log Q+O(1).

Proof of Lemma 3.2.

Lemma 3.2 follows from Lemma 3.1 (in the case a=11nka=1-\frac{1}{n_{k}}) and partial summation. ∎

Proof of Lemma 3.3.

The first inequality holds because σa(𝔫)1\sigma_{a}({\mathfrak{n}})\geq 1 by definition.

Recall the function d(𝔫)d({\mathfrak{n}}) in Section 2. For any ε>0{\varepsilon}>0, d(𝔫)N𝔫εd({\mathfrak{n}})\ll{\mathrm{N}}{\mathfrak{n}}^{\varepsilon}. We have

N𝔫Qσa2(𝔫)\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\sigma_{a}^{2}({\mathfrak{n}}) =\displaystyle= N𝔫Q𝔡,𝔢|𝔫N𝔡aN𝔢a=N𝔡QN𝔢QN𝔡aN𝔢aN𝔫Q[𝔡,𝔢]|𝔫1Q𝔡,𝔢N𝔡aN𝔢aN[𝔡,𝔢]1\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\sum_{{\mathfrak{d}},{\mathfrak{e}}|{\mathfrak{n}}}{\mathrm{N}}{\mathfrak{d}}^{a}{\mathrm{N}}{\mathfrak{e}}^{a}=\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{d}}\leq Q\\ {\mathrm{N}}{\mathfrak{e}}\leq Q\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{a}{\mathrm{N}}{\mathfrak{e}}^{a}\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ [{\mathfrak{d}},{\mathfrak{e}}]|{\mathfrak{n}}\end{subarray}}1\ll Q\sum_{{\mathfrak{d}},{\mathfrak{e}}}{\mathrm{N}}{\mathfrak{d}}^{a}{\mathrm{N}}{\mathfrak{e}}^{a}{\mathrm{N}}[{\mathfrak{d}},{\mathfrak{e}}]^{-1}
\displaystyle\leq Q𝔡,𝔢N[𝔡,𝔢]1+aQ𝔮d2(𝔮)N𝔮1+aaQ.\displaystyle Q\sum_{{\mathfrak{d}},{\mathfrak{e}}}{\mathrm{N}}[{\mathfrak{d}},{\mathfrak{e}}]^{-1+a}\leq Q\sum_{{\mathfrak{q}}}d^{2}({\mathfrak{q}}){\mathrm{N}}{\mathfrak{q}}^{-1+a}\ll_{a}Q.

Proof of Lemma 3.4.

We only prove the first statement. The second statement follows from the same method. Using partial summation, we write

N𝔫Q1N𝔫(log(2QN𝔫))2\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{1}{{\mathrm{N}}{\mathfrak{n}}(\log(\frac{2Q}{{\mathrm{N}}{\mathfrak{n}}}))^{2}} =\displaystyle= N𝔫Q1Q(log(2QQ))2N𝔫Q[1Q(log(2QQ))21N𝔫(log(2QN𝔫))2]\displaystyle\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{1}{Q(\log(\frac{2Q}{Q}))^{2}}-\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\left[\frac{1}{Q(\log(\frac{2Q}{Q}))^{2}}-\frac{1}{{\mathrm{N}}{\mathfrak{n}}(\log(\frac{2Q}{{\mathrm{N}}{\mathfrak{n}}}))^{2}}\right]
=\displaystyle= O(1)+N𝔫QN𝔫Qlog2Qlogt2t2(log2Qlogt)3𝑑t\displaystyle O(1)+\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\int_{{\mathrm{N}}{\mathfrak{n}}}^{Q}\frac{\log 2Q-\log t-2}{t^{2}(\log 2Q-\log t)^{3}}dt
=\displaystyle= 1Qlog2Qlogt2t2(log2Qlogt)3(N𝔫t1)𝑑t+O(1)\displaystyle\int_{1}^{Q}\frac{\log 2Q-\log t-2}{t^{2}(\log 2Q-\log t)^{3}}\left(\sum_{{\mathrm{N}}{\mathfrak{n}}\leq t}1\right)dt+O(1)
=\displaystyle= O(1Qlog2Qlogt2t(log2Qlogt)3𝑑t)\displaystyle O\left(\int_{1}^{Q}\frac{\log 2Q-\log t-2}{t(\log 2Q-\log t)^{3}}dt\right)
=\displaystyle= O(1Q1t(log2Qlogt)2𝑑t)+O(1Q2t(log2Qlogt)3𝑑t)\displaystyle O\left(\int_{1}^{Q}\frac{1}{t(\log 2Q-\log t)^{2}}dt\right)+O\left(\int_{1}^{Q}\frac{2}{t(\log 2Q-\log t)^{3}}dt\right)
=\displaystyle= O(1).\displaystyle O(1).

Proof of Lemma 3.5.

Let a𝔫=μk2(𝔫)𝔭|𝔫(11N𝔭)1a_{\mathfrak{n}}=\mu_{k}^{2}({\mathfrak{n}})\prod_{{\mathfrak{p}}|{\mathfrak{n}}}(1-\frac{1}{{\mathrm{N}}{\mathfrak{p}}})^{-1}. Then for (s)>1\Re(s)>1, we have

(6.1) 𝔫a𝔫N𝔫s=𝔭(1+1N𝔭s(11N𝔭)1)=ζk(s)𝔪b𝔪N𝔪s\sum_{{\mathfrak{n}}}\frac{a_{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{n}}^{s}}=\prod_{\mathfrak{p}}(1+\frac{1}{{\mathrm{N}}{\mathfrak{p}}^{s}}(1-\frac{1}{{\mathrm{N}}{\mathfrak{p}}})^{-1})=\zeta_{k}(s)\sum_{{\mathfrak{m}}}\frac{b_{\mathfrak{m}}}{{\mathrm{N}}{\mathfrak{m}}^{s}}

where

𝔪b𝔪N𝔪s=𝔭(1+1N𝔭s(11N𝔭)1)(11N𝔭s)=𝔭(1+1N𝔭s1N𝔭11N𝔭2sN𝔭N𝔭1)\sum_{{\mathfrak{m}}}\frac{b_{\mathfrak{m}}}{{\mathrm{N}}{\mathfrak{m}}^{s}}=\prod_{{\mathfrak{p}}}(1+\frac{1}{{\mathrm{N}}{\mathfrak{p}}^{s}}(1-\frac{1}{{\mathrm{N}}{\mathfrak{p}}})^{-1})(1-\frac{1}{{\mathrm{N}}{\mathfrak{p}}^{s}})=\prod_{\mathfrak{p}}(1+\frac{1}{{\mathrm{N}}{\mathfrak{p}}^{s}}\cdot\frac{1}{{\mathrm{N}}{\mathfrak{p}}-1}-\frac{1}{{\mathrm{N}}{\mathfrak{p}}^{2s}}\cdot\frac{{\mathrm{N}}{\mathfrak{p}}}{{\mathrm{N}}{\mathfrak{p}}-1})

and 𝔪b𝔪N𝔪s\displaystyle\sum_{{\mathfrak{m}}}\frac{b_{\mathfrak{m}}}{{\mathrm{N}}{\mathfrak{m}}^{s}} is absolutely convergent for (s)>12\Re(s)>\frac{1}{2}. Here, the sequence {a𝔫}\{a_{\mathfrak{n}}\} can be regarded as the convolution of the constant sequence 11 and the sequence {b𝔪}\{b_{\mathfrak{m}}\}. Let F(Q)=1sk𝔡N𝔡Q1\displaystyle F(Q)=\frac{1}{s_{k}}\sum_{\begin{subarray}{c}{\mathfrak{d}}\\ {\mathrm{N}}{\mathfrak{d}}\leq Q\end{subarray}}1 and let Gv(Q)=N𝔪Q|b𝔪|\displaystyle G_{v}(Q)=\sum_{{\mathrm{N}}{\mathfrak{m}}\leq Q}|b_{\mathfrak{m}}|. Then

F(Q)=Q+O(Q11nk),Gv(Q)=O(Q12+ε) for any ε>0.F(Q)=Q+O(Q^{1-\frac{1}{n_{k}}}),\ \ \ G_{v}(Q)=O(Q^{\frac{1}{2}+{\varepsilon}})\text{ for any }{\varepsilon}>0.

The sum N𝔫Qa𝔫\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}a_{\mathfrak{n}} can be estimated from the bounds of F(Q)F(Q) and Gv(Q)G_{v}(Q) via the stability theorem, e.g., [BD04, Theorem 3.29]. In particular, we have

N𝔫Qa𝔫=AQ+{O(Q12+ε) for any ε>0nk=2,O(Q11nk)nk3,\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}a_{\mathfrak{n}}=AQ+\begin{cases}O(Q^{\frac{1}{2}+{\varepsilon}})\text{ for any }{\varepsilon}>0&n_{k}=2,\\ O(Q^{1-\frac{1}{n_{k}}})&n_{k}\geq 3,\end{cases}

where A=lims1+(s1)𝔫a𝔫N𝔫s.\displaystyle A=\lim_{s\to 1^{+}}(s-1)\sum_{{\mathfrak{n}}}\frac{a_{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{n}}^{s}}. Since 𝔪b𝔪N𝔪s1\displaystyle\sum_{{\mathfrak{m}}}\frac{b_{\mathfrak{m}}}{{\mathrm{N}}{\mathfrak{m}}^{s}}\to 1 as s1+s\to 1^{+}, we have A=Ress=1ζk(s)=skA=\mathrm{Res}_{s=1}\zeta_{k}(s)=s_{k} by (6.1).

Lemma 3.5 follows from partial summation:

N𝔫Qμk2(𝔫)φ(𝔫)=N𝔫Qa𝔫N𝔫=Q1N𝔫Qa𝔫+1Qu2(N𝔫ua𝔫)𝑑u=sklogQ+O(1).\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{\mu_{k}^{2}({\mathfrak{n}})}{\varphi({\mathfrak{n}})}=\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\frac{a_{\mathfrak{n}}}{{\mathrm{N}}{\mathfrak{n}}}=Q^{-1}\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}a_{\mathfrak{n}}+\int_{1}^{Q}u^{-2}\left(\sum_{{\mathrm{N}}{\mathfrak{n}}\leq u}a_{\mathfrak{n}}\right)du=s_{k}\log Q+O(1).

Proof of Lemma 3.6.

We prove this lemma by the inclusion-exclusion principle.

Let 𝒜{\mathcal{A}} be the set of all squarefree ideals in 𝒪k{\mathscr{O}}_{k} with norm at most QQ. For a set XX in {𝔫:N𝔫Q}\{{\mathfrak{n}}:{\mathrm{N}}{\mathfrak{n}}\leq Q\}, denote X¯\overline{X} to be the complement of XX. For any prime ideal 𝔮{\mathfrak{q}}, let 𝒜𝔮={𝔫:𝔮|𝔫,N𝔫Q}{\mathcal{A}}_{\mathfrak{q}}=\{{\mathfrak{n}}:{\mathfrak{q}}|{\mathfrak{n}},{\mathrm{N}}{\mathfrak{n}}\leq Q\} and let MM denote the largest number of prime ideals 𝔮1,,𝔮M{\mathfrak{q}}_{1},\dots,{\mathfrak{q}}_{M} such that N𝔮1N𝔮MQ{\mathrm{N}}{\mathfrak{q}}_{1}\dots\mathrm{N}{\mathfrak{q}}_{M}\leq\sqrt{Q}. Then by the inclusion-exclusion principle, we have

(6.2) |𝒜|=|𝔮 prime 𝒜𝔮¯|=m=0M(1)m𝔮1,,𝔮m|𝒜𝔮1𝒜𝔮m|.|{\mathcal{A}}|=\left|\bigcap_{{\mathfrak{q}}\text{ prime }}\overline{{\mathcal{A}}_{\mathfrak{q}}}\right|=\sum_{m=0}^{M}(-1)^{m}\sum_{{\mathfrak{q}}_{1},\dots,{\mathfrak{q}}_{m}}\left|{\mathcal{A}}_{{\mathfrak{q}}_{1}}\cap\dots\cap{\mathcal{A}}_{{\mathfrak{q}}_{m}}\right|.

Denote S:=𝒜𝔮1𝒜𝔮mS:={\mathcal{A}}_{{\mathfrak{q}}_{1}}\cap\dots\cap{\mathcal{A}}_{{\mathfrak{q}}_{m}}. Then

S={N𝔫Q:𝔮12𝔮m2|𝔫}={𝔯:N𝔯QN𝔮1N𝔮m}=skQN𝔮12N𝔮m2+O((QN𝔮12N𝔮m2)11nk).S=\{{\mathrm{N}}{\mathfrak{n}}\leq Q:{\mathfrak{q}}_{1}^{2}\dots\mathfrak{q}_{m}^{2}|{\mathfrak{n}}\}=\{{\mathfrak{r}}:{\mathrm{N}}{\mathfrak{r}}\leq\frac{Q}{{\mathrm{N}}{\mathfrak{q}}_{1}\dots\mathrm{N}{\mathfrak{q}}_{m}}\}=\frac{s_{k}Q}{{\mathrm{N}}{\mathfrak{q}}_{1}^{2}\dots\mathrm{N}{\mathfrak{q}}_{m}^{2}}+O((\frac{Q}{{\mathrm{N}}{\mathfrak{q}}_{1}^{2}\dots\mathrm{N}{\mathfrak{q}}_{m}^{2}})^{1-\frac{1}{n_{k}}}).

Plugging this into (6.2), we have

|𝒜|\displaystyle|{\mathcal{A}}| =\displaystyle= m=0M(1)m𝔮1,,𝔮mskQN𝔮12N𝔮m2+O(m=0M𝔮1,,𝔮m(QN𝔮12N𝔮m2)11nk)\displaystyle\sum_{m=0}^{M}(-1)^{m}\sum_{{\mathfrak{q}}_{1},\dots,{\mathfrak{q}}_{m}}\frac{s_{k}Q}{{\mathrm{N}}{\mathfrak{q}}_{1}^{2}\dots\mathrm{N}{\mathfrak{q}}_{m}^{2}}+O(\sum_{m=0}^{M}\sum_{{\mathfrak{q}}_{1},\dots,{\mathfrak{q}}_{m}}(\frac{Q}{{\mathrm{N}}{\mathfrak{q}}_{1}^{2}\dots\mathrm{N}{\mathfrak{q}}_{m}^{2}})^{1-\frac{1}{n_{k}}})
=\displaystyle= skQN𝔡Qμk(𝔡)N𝔡2+Q11nkO(N𝔡Q1N𝔡22nk)\displaystyle s_{k}Q\sum_{{\mathrm{N}}{\mathfrak{d}}\leq\sqrt{Q}}\frac{\mu_{k}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}^{2}}+Q^{1-\frac{1}{n_{k}}}O(\sum_{{\mathrm{N}}{\mathfrak{d}}\leq\sqrt{Q}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2-\frac{2}{n_{k}}}})
=\displaystyle= skQ𝔡μk(𝔡)N𝔡2skQN𝔡>Qμk(𝔡)N𝔡2+Q11nkO(N𝔡Q1N𝔡22nk)\displaystyle s_{k}Q\sum_{{\mathfrak{d}}}\frac{\mu_{k}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}^{2}}-s_{k}Q\sum_{{\mathrm{N}}{\mathfrak{d}}>\sqrt{Q}}\frac{\mu_{k}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}^{2}}+Q^{1-\frac{1}{n_{k}}}O(\sum_{{\mathrm{N}}{\mathfrak{d}}\leq\sqrt{Q}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2-\frac{2}{n_{k}}}})
=\displaystyle= skQζk(2)+Q11nkO(N𝔡Q1N𝔡22nk).\displaystyle\frac{s_{k}Q}{\zeta_{k}(2)}+Q^{1-\frac{1}{n_{k}}}O(\sum_{{\mathrm{N}}{\mathfrak{d}}\leq\sqrt{Q}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2-\frac{2}{n_{k}}}}).

If nk=2n_{k}=2, |𝒜|=skQζk(2)+O(Q12+εk)|{\mathcal{A}}|=\frac{s_{k}Q}{\zeta_{k}(2)}+O(Q^{\frac{1}{2}+{\varepsilon}_{k}}) for any εk>0{\varepsilon}_{k}>0; if nk3n_{k}\geq 3, |𝒜|=skQζk(2)+O(Q11nk)|{\mathcal{A}}|=\frac{s_{k}Q}{\zeta_{k}(2)}+O(Q^{1-\frac{1}{n_{k}}}). ∎

Proof of Lemma 3.7.

For any ideal 𝔯{\mathfrak{r}}, let

𝒟𝔯:={𝔡:𝔭|𝔡𝔭|𝔯}.{\mathcal{D}}_{\mathfrak{r}}:=\{{\mathfrak{d}}:{\mathfrak{p}}|{\mathfrak{d}}\Rightarrow{\mathfrak{p}}|{\mathfrak{r}}\}.

Then we have

𝔡,𝔪𝔡𝒟𝔯𝔡𝔪=𝔫λ(𝔡)μk2(𝔪)={μk2(𝔫) if (𝔫,𝔯)=(1),0 if (𝔫,𝔯)(1).\sum_{\begin{subarray}{c}{\mathfrak{d}},{\mathfrak{m}}\\ {\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathfrak{d}}{\mathfrak{m}}={\mathfrak{n}}\end{subarray}}\lambda({\mathfrak{d}})\mu_{k}^{2}({\mathfrak{m}})=\begin{cases}\mu_{k}^{2}({\mathfrak{n}})&\text{ if }({\mathfrak{n}},{\mathfrak{r}})=(1),\\ 0&\text{ if }({\mathfrak{n}},{\mathfrak{r}})\neq(1).\end{cases}

Thus,

N𝔫Q(𝔫,𝔯)=(1)μk2(𝔫)\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\mu_{k}^{2}({\mathfrak{n}}) =\displaystyle= 𝔡𝒟𝔯λ(𝔡)N𝔪QN𝔡μk2(𝔪)\displaystyle\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}\lambda({\mathfrak{d}})\sum_{{\mathrm{N}}{\mathfrak{m}}\leq\frac{Q}{{\mathrm{N}}{\mathfrak{d}}}}\mu_{k}^{2}({\mathfrak{m}})
=\displaystyle= skQζk(2)𝔡𝒟𝔯λ(𝔡)N𝔡+O(Q11nk+εk𝔡𝒟𝔯N𝔡1+1nkεk)\displaystyle\frac{s_{k}Q}{\zeta_{k}(2)}\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}\frac{\lambda({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}}+O(Q^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}{\mathrm{N}}{\mathfrak{d}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}})
=\displaystyle= skζk(2)N𝔯κ(𝔯)Q+O(Q11nk+εk𝔭|𝔯11N𝔭1+1nkεk)\displaystyle\frac{s_{k}}{\zeta_{k}(2)}\frac{{\mathrm{N}}{\mathfrak{r}}}{\kappa({\mathfrak{r}})}Q+O(Q^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\prod_{{\mathfrak{p}}|{\mathfrak{r}}}\frac{1}{1-{\mathrm{N}}{\mathfrak{p}}^{-1+\frac{1}{n_{k}}-{\varepsilon}_{k}}})
=\displaystyle= skζk(2)N𝔯κ(𝔯)Q+O(Q11nk+εk𝔭|𝔯(1+1N𝔭11nk+εk1))\displaystyle\frac{s_{k}}{\zeta_{k}(2)}\frac{{\mathrm{N}}{\mathfrak{r}}}{\kappa({\mathfrak{r}})}Q+O(Q^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\prod_{{\mathfrak{p}}|{\mathfrak{r}}}(1+\frac{1}{{\mathrm{N}}{\mathfrak{p}}^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}-1}))
=\displaystyle= skζk(2)N𝔯κ(𝔯)Q+O(Q11nk+εkσ1nk+1(𝔯)).\displaystyle\frac{s_{k}}{\zeta_{k}(2)}\frac{{\mathrm{N}}{\mathfrak{r}}}{\kappa({\mathfrak{r}})}Q+O(Q^{1-\frac{1}{n_{k}}+{\varepsilon}_{k}}\sigma_{-\frac{1}{n_{k}+1}}({\mathfrak{r}})).

Proof of Lemma 3.9.

For (3.1), we will prove the following stronger form:

(6.3) N𝔫Qμk(𝔫)Qβ0β0ζk(β0)Qexp(c12(logQ)1/10nk2),\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\mu_{k}({\mathfrak{n}})-\frac{Q^{\beta_{0}}}{\beta_{0}\zeta_{k}^{{}^{\prime}}(\beta_{0})}\ll Q\exp(-\frac{c_{1}}{2}(\log Q)^{1/10}n_{k}^{-2}),

where c1=min{c,106}c_{1}=\min\{c,10^{-6}\}, cc is the absolute constant in Theorem B. The term Qβ0β0ζk(β0)\frac{Q^{\beta_{0}}}{\beta_{0}\zeta_{k}^{{}^{\prime}}(\beta_{0})} exists if and only if the Siegel zero exists. Note that this form is equivalent to the effective prime ideal theorem (see e.g., [TZ17]). For completeness, we give a proof of (6.3). The approach of the proof is similar to the proof of Theorem 1.2 in [FM12]. However, the error term in [FM12, Theorem 1.2] appears to be ineffective, and [FM12, p.7] appears to omit the bound for the integral from t0-t_{0} to t0t_{0}. Thus, we rewrite the proof as follows.

A direct approach to prove (6.3) has a problem since there may be many ideals with the same norm. Thus, we apply the following result of Liu and Ye.

Theorem C.

[LY07, Theorem 2.1] Let f(s)=n=1annsf(s)=\sum_{n=1}^{\infty}a_{n}n^{-s} converge absolutely for σ>σ0>0\sigma>\sigma_{0}>0, and let B(σ)=n=1|an|nσB(\sigma)=\sum_{n=1}^{\infty}|a_{n}|n^{-\sigma}. Then for b>σ0b>\sigma_{0}, x2x\geq 2, T2T\geq 2, and H2H\geq 2, we have

nxan=12πibiTb+iTf(s)xss𝑑s+O(xx/H<nx+x/H|an|)+O(xbHB(b)T).\sum_{n\leq x}a_{n}=\frac{1}{2\pi i}\int_{b-iT}^{b+iT}f(s)\frac{x^{s}}{s}ds+O\left(\sum_{x-x/H<n\leq x+x/H}|a_{n}|\right)+O\left(\frac{x^{b}HB(b)}{T}\right).

Let a=1c1nk2(log|dk|(T+3)nk)9a=1-\frac{c_{1}}{n_{k}^{2}(\log|d_{k}|(T+3)^{n_{k}})^{9}}, where c1c_{1} is the absolute constant we defined in the beginning of the proof. We apply Theorem C for x=Qx=Q, f(s)=1ζk(s),b=1+1logQ,H=Tf(s)=\frac{1}{\zeta_{k}(s)},b=1+\frac{1}{\log Q},H=\sqrt{T} to get

N𝔮Qμk(𝔮)\displaystyle\sum_{{\mathrm{N}}{\mathfrak{q}}\leq Q}\mu_{k}({\mathfrak{q}}) =\displaystyle= 12πi1+1logQiT1+1logQ+iT1ζk(s)Qss𝑑s\displaystyle\frac{1}{2\pi i}\int_{1+\frac{1}{\log Q}-iT}^{1+\frac{1}{\log Q}+iT}\frac{1}{\zeta_{k}(s)}\frac{Q^{s}}{s}ds
+O((Q+QT)(QQT)+Q11nk)+O(Qζk(1+1logQ)T).\displaystyle+O((Q+\frac{Q}{\sqrt{T}})-(Q-\frac{Q}{\sqrt{T}})+Q^{1-\frac{1}{n_{k}}})+O\left(\frac{Q\zeta_{k}(1+\frac{1}{\log Q})}{\sqrt{T}}\right).

For the last term, we apply ζk(s)=sks1+O(1)\zeta_{k}(s)=\frac{s_{k}}{s-1}+O(1) to get ζk(1+1logQ)=O(logQ)\zeta_{k}(1+\frac{1}{\log Q})=O(\log Q). We will choose TT to satisfy TQεT\ll Q^{\varepsilon} for any ε>0{\varepsilon}>0, so the last error term dominates and we have

(6.4) N𝔮Qμk(𝔮)=12πi1+1logQiT1+1logQ+iT1ζk(s)Qss𝑑s+O(QlogQT).\sum_{{\mathrm{N}}{\mathfrak{q}}\leq Q}\mu_{k}({\mathfrak{q}})=\frac{1}{2\pi i}\int_{1+\frac{1}{\log Q}-iT}^{1+\frac{1}{\log Q}+iT}\frac{1}{\zeta_{k}(s)}\frac{Q^{s}}{s}ds+O\left(\frac{Q\log Q}{\sqrt{T}}\right).

Let ψ(t)=nk2(log|dk|(|t|+3)nk)9\psi(t)=n_{k}^{2}(\log|d_{k}|(|t|+3)^{n_{k}})^{9}, so that a=1c1ψ(T)a=1-\frac{c_{1}}{\psi(T)}. Put

l(t)={1c1ψ(10)|t|10,1c1ψ(t)10|t|T.l(t)=\begin{cases}1-\frac{c_{1}}{\psi(10)}&|t|\leq 10,\\ 1-\frac{c_{1}}{\psi(t)}&10\leq|t|\leq T.\end{cases}

By the residue theorem and Theorem B, we have

12πi1+1logQiT1+1logQ+iT1ζk(s)Qss𝑑s\displaystyle\frac{1}{2\pi i}\int_{1+\frac{1}{\log Q}-iT}^{1+\frac{1}{\log Q}+iT}\frac{1}{\zeta_{k}(s)}\frac{Q^{s}}{s}ds =\displaystyle= Ress=β01ζk(s)Qβ0β0\displaystyle\mathrm{Res}_{s=\beta_{0}}\frac{1}{\zeta_{k}(s)}\frac{Q^{\beta_{0}}}{\beta_{0}}
+12πi(biTaiT+l(t),t=Tt=T+a+iTb+iT)1ζk(s)Qssds\displaystyle+\frac{1}{2\pi i}\left(\int_{b-iT}^{a-iT}+\int_{l(t),\ t=-T}^{t=T}+\int_{a+iT}^{b+iT}\right)\frac{1}{\zeta_{k}(s)}\frac{Q^{s}}{s}ds
=:\displaystyle=: Qβ0β0ζk(β0)+I1+I2+I3.\displaystyle\frac{Q^{\beta_{0}}}{\beta_{0}\zeta_{k}^{{}^{\prime}}(\beta_{0})}+I_{1}+I_{2}+I_{3}.

The term Qβ0β0ζk(β0)\frac{Q^{\beta_{0}}}{\beta_{0}\zeta_{k}^{{}^{\prime}}(\beta_{0})} exists if and only if the Siegel zero exists.

To proceed, a bound for 1ζk(s)\frac{1}{\zeta_{k}(s)} is necessary. We will obtain the bound for 1ζk(s)\frac{1}{\zeta_{k}(s)} from a bound for ζkζk(s)\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(s), which we can find in [Lan03, p.656]. Let σ1=1c1ψ(10)\sigma_{1}=1-\frac{c_{1}}{\psi(10)}. If the Siegel zero β0\beta_{0} exists and σ1<β0<1\sigma_{1}<\beta_{0}<1, we cannot let σ1\sigma_{1} and β0\beta_{0} be arbitrarily close (see (6) below). We can achieve this by the following method. There are two possibilities: either 1+σ12<β0\frac{1+\sigma_{1}}{2}<\beta_{0} or 1+σ12β0\frac{1+\sigma_{1}}{2}\geq\beta_{0}. If we are in the latter case, we choose c1=c14c_{1}^{{}^{\prime}}=\frac{c_{1}}{4} and σ1=1c1ψ(10)\sigma_{1}^{{}^{\prime}}=1-\frac{c_{1}^{{}^{\prime}}}{\psi(10)}. Let c1,σ1c_{1}^{{}^{\prime}},\sigma_{1}^{{}^{\prime}} be our new values of c1,σ1c_{1},\sigma_{1}. Then our new value satisfies β0<σ1\beta_{0}<\sigma_{1}. In this case, our argument below still holds and all the terms involving β0\beta_{0} are omitted, since we will only consider the region to the right of σ1\sigma_{1}. Therefore, we can assume that our choice of σ1\sigma_{1} satisfies 1+σ12<β0\frac{1+\sigma_{1}}{2}<\beta_{0} (i.e., β0σ1>12(1σ1)\beta_{0}-\sigma_{1}>\frac{1}{2}(1-\sigma_{1})) without loss of generality.

Let s=σ+its=\sigma+it. Then ζkζk(s)-\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(s) is regular for σl(t)\sigma\geq l(t) except at s=1s=1 and s=β0s=\beta_{0} (if the Siegel zero exists and satisfies β0σ1>12(1σ1)\beta_{0}-\sigma_{1}>\frac{1}{2}(1-\sigma_{1})) with both residues equal to 11 and 1-1, respectively, and

ζkζk(s)={1sβ0+1s1+O(1)l(t)σ2,|t|10,O(ψ(t))l(t)σ2,|t|10.-\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(s)=\begin{cases}\frac{-1}{s-\beta_{0}}+\frac{1}{s-1}+O(1)&l(t)\leq\sigma\leq 2,|t|\leq 10,\\ O(\psi(t))&l(t)\leq\sigma\leq 2,|t|\geq 10.\end{cases}

Thus, there exists an absolute constant CC such that |ζkζk(s)|Cψ(t)\left|\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(s)\right|\leq C\psi(t) for ss in the range l(t)σ2,|t|10l(t)\leq\sigma\leq 2,|t|\geq 10.

To obtain a bound of 1ζk(s)\frac{1}{\zeta_{k}(s)}, we compute for (s)=σ1c1ψ((s))\Re(s)=\sigma\geq 1-\frac{c_{1}}{\psi(\Im(s))}, |(s)|=t10|\Im(s)|=t\geq 10, following [Ivi12, p. 311],

log1|ζk(s)|\displaystyle\log\frac{1}{|\zeta_{k}(s)|} =\displaystyle= logζk(s)\displaystyle-\Re\log\zeta_{k}(s)
=\displaystyle= logζk(1+1ψ(t)+it)+σ1+1ψ(t)ζkζk(u+it)𝑑u\displaystyle-\Re\log\zeta_{k}(1+\frac{1}{\psi(t)}+it)+\int_{\sigma}^{1+\frac{1}{\psi(t)}}\Re\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(u+it)du
\displaystyle\leq logζk(1+1ψ(t))+σ1+1ψ(t)Cψ(t)𝑑u\displaystyle\log\zeta_{k}(1+\frac{1}{\psi(t)})+\int_{\sigma}^{1+\frac{1}{\psi(t)}}C\psi(t)du
\displaystyle\leq logCψ(t)+O(1).\displaystyle\log C\psi(t)+O(1).

For (s)=σ=σ1=1c1ψ(10)\Re(s)=\sigma=\sigma_{1}=1-\frac{c_{1}}{\psi(10)}, 0<|(s)|=t100<|\Im(s)|=t\leq 10, we compute (recalling β0σ>12(1σ)\beta_{0}-\sigma>\frac{1}{2}(1-\sigma))

log1|ζk(s)|\displaystyle\log\frac{1}{|\zeta_{k}(s)|} =\displaystyle= logζk(s)\displaystyle-\Re\log\zeta_{k}(s)
=\displaystyle= logζk(1+1ψ(10)+it)+σ1+1ψ(10)ζkζk(u+it)𝑑u\displaystyle-\Re\log\zeta_{k}(1+\frac{1}{\psi(10)}+it)+\int_{\sigma}^{1+\frac{1}{\psi(10)}}\Re\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(u+it)du
\displaystyle\leq logζk(1+1ψ(10))+σ1+1ψ(10)(1u+itβ0+1u+it1)𝑑u+O(1)\displaystyle\log\zeta_{k}(1+\frac{1}{\psi(10)})+\int_{\sigma}^{1+\frac{1}{\psi(10)}}\Re(\frac{-1}{u+it-\beta_{0}}+\frac{1}{u+it-1})du+O(1)
=\displaystyle= 12(log((1+1ψ(10)β0)2+t2)log((σβ0)2+t2))\displaystyle\frac{1}{2}(\log((1+\frac{1}{\psi(10)}-\beta_{0})^{2}+t^{2})-\log((\sigma-\beta_{0})^{2}+t^{2}))
+12(log((1ψ(10))2+t2)log((σ1)2+t2))+O(1)\displaystyle+\frac{1}{2}(\log((\frac{1}{\psi(10)})^{2}+t^{2})-\log((\sigma-1)^{2}+t^{2}))+O(1)
=\displaystyle= O(1)+O(log(c12+t2))\displaystyle O(1)+O(\log(c_{1}^{2}+t^{2}))
=\displaystyle= O(1).\displaystyle O(1).

Therefore,

(6.6) 1ζk(s){ψ(t)l(t)σ2,|t|10,1σ=l(t)=1c1ψ(10),|t|10.\frac{1}{\zeta_{k}(s)}\ll\begin{cases}\psi(t)&l(t)\leq\sigma\leq 2,|t|\geq 10,\\ 1&\sigma=l(t)=1-\frac{c_{1}}{\psi(10)},|t|\leq 10.\end{cases}

We apply (6.6) to estimate I1,I2,I3I_{1},I_{2},I_{3}. For I1I_{1},

(6.7) |I1|12πab|1ζk(σiT)|Qσ|σiT|𝑑σ(logT)9T1abQσ𝑑σQT1(logT)9.|I_{1}|\leq\frac{1}{2\pi}\int_{a}^{b}\left|\frac{1}{\zeta_{k}(\sigma-iT)}\right|\frac{Q^{\sigma}}{|\sigma-iT|}d\sigma\ll(\log T)^{9}T^{-1}\int_{a}^{b}Q^{\sigma}d\sigma\ll QT^{-1}(\log T)^{9}.

The same bound holds for I3I_{3}. For I2I_{2},

(6.8) |I2|\displaystyle|I_{2}| \displaystyle\leq 12π(l(t),t=Tt=10+l(t),t=10t=10+l(t),t=10t=T)|1ζk(σ+it)|Qσ|σ+it|ds\displaystyle\frac{1}{2\pi}\left(\int_{l(t),t=-T}^{t=-10}+\int_{l(t),t=-10}^{t=10}+\int_{l(t),t=10}^{t=T}\right)\left|\frac{1}{\zeta_{k}(\sigma+it)}\right|\frac{Q^{\sigma}}{|\sigma+it|}ds
\displaystyle\ll Qa10T(logT)91|a+it|𝑑tQa(logT)10.\displaystyle Q^{a}\int_{10}^{T}(\log T)^{9}\frac{1}{|a+it|}dt\ll Q^{a}(\log T)^{10}.

Our choice of TT will balance the big O terms in (6.4) and (6.8). Note that the term in (6.7) is QlogQT\ll\frac{Q\log Q}{\sqrt{T}}, which is the term in (6.4). Upon choosing

(6.9) T=exp((logQ)110log|dk|nk)3,T=\exp(\frac{(\log Q)^{\frac{1}{10}}-\log|d_{k}|}{n_{k}})-3,

we see that the term in (6.4) is bounded above by

QlogQexp((logQ)110log|dk|nk)Qexp(12(logQ)1/10nk1)Q\log Q\cdot\exp(-\frac{(\log Q)^{\frac{1}{10}}-\log|d_{k}|}{n_{k}})\ll Q\exp(-\frac{1}{2}(\log Q)^{1/10}n_{k}^{-1})

and the term in (6.8) is bounded above by

Q1c1nk2(log(|dk|exp((logQ)110log|dk|)))9(logT)10\displaystyle Q^{1-\frac{c_{1}}{n_{k}^{2}(\log(|d_{k}|\exp((\log Q)^{\frac{1}{10}}-\log|d_{k}|)))^{9}}}(\log T)^{10} =\displaystyle= Q1c1nk2(logQ)910(logT)10\displaystyle Q^{1-\frac{c_{1}}{n_{k}^{2}(\log Q)^{\frac{9}{10}}}}(\log T)^{10}
\displaystyle\ll Qexp(c12(logQ)1/10nk2).\displaystyle Q\exp(-\frac{c_{1}}{2}(\log Q)^{1/10}n_{k}^{-2}).

Since we assumed T10T\geq 10, by (6.9), our bound holds for Qexp((nklog13+log|dk|)10)Q\geq\exp((n_{k}\log 13+\log|d_{k}|)^{10}). If Q<exp((nklog13+log|dk|)10)Q<\exp((n_{k}\log 13+\log|d_{k}|)^{10}), then N𝔫Qμk(𝔫)1\sum_{{\mathrm{N}}{\mathfrak{n}}\leq Q}\mu_{k}({\mathfrak{n}})\ll 1. This finishes the proof of (6.3), hence (3.1) holds.

For (3.2), we follow the proof of (3.1) but choose f(s)=1ζk(s+1)f(s)=\frac{1}{\zeta_{k}(s+1)} instead. The Dirichlet series is f(s)=𝔮a𝔮=μk(𝔮)N𝔮s+1f(s)=\sum_{\mathfrak{q}}a_{\mathfrak{q}}=\frac{\mu_{k}({\mathfrak{q}})}{{\mathrm{N}}{\mathfrak{q}}^{s+1}}. In this new setting, we choose b=1logQb=\frac{1}{\log Q}. Then the proof of (3.1) is adapted here.

For (3.3), we follow the proof of (3.1) but choose f(s)=ζkζk2(s+1)f(s)=\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}^{2}}(s+1) instead. The Dirichlet series is f(s)=𝔮μk(𝔮)logN𝔮N𝔮s+1f(s)=\sum_{\mathfrak{q}}\frac{\mu_{k}({\mathfrak{q}})\log{\mathrm{N}}{\mathfrak{q}}}{{\mathrm{N}}{\mathfrak{q}}^{s+1}}. In this new setting, we choose b=1logQb=\frac{1}{\log Q}. Then the proof of (3.1) is adapted here. Note that there is a pole at s=0s=0, and the residue is

Ress=0ζkζk2(s+1)Qss=Ress=1ζkζk2(s)=1Ress=1ζk(s)=1sk.\text{Res}_{s=0}\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}^{2}}(s+1)\cdot\frac{Q^{s}}{s}=\text{Res}_{s=1}\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}^{2}}(s)=-\frac{1}{\text{Res}_{s=1}\zeta_{k}(s)}=-\frac{1}{s_{k}}.

There is also a possible pole of order 2 at s=β01s=\beta_{0}-1 if the Siegel zero exists, which gives the term Qβ01[(β01)logQ1](β01)2ζk(β0)\frac{Q^{\beta_{0}-1}[(\beta_{0}-1)\log Q-1]}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}. Note also that the bound for ζkζk2(s+1)\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}^{2}}(s+1) comes from multiplying the bound for ζkζk(s+1)\frac{\zeta_{k}^{{}^{\prime}}}{\zeta_{k}}(s+1) and the bound for 1ζk(s+1)\frac{1}{\zeta_{k}}(s+1).

Proof of Lemma 3.10.

For any integral ideal 𝔯{\mathfrak{r}}, again let

𝒟𝔯:={𝔡:𝔭|𝔡𝔭|𝔯}.{\mathcal{D}}_{\mathfrak{r}}:=\{{\mathfrak{d}}:{\mathfrak{p}}|{\mathfrak{d}}\Rightarrow{\mathfrak{p}}|{\mathfrak{r}}\}.

Then it is clear that

𝔡𝒟𝔯𝔡|𝔫μk(𝔫𝔡)={μk(𝔫)(𝔫,𝔯)=(1),0(𝔫,𝔯)(1).\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathfrak{d}}|{\mathfrak{n}}\end{subarray}}\mu_{k}(\frac{{\mathfrak{n}}}{{\mathfrak{d}}})=\begin{cases}\mu_{k}({\mathfrak{n}})&({\mathfrak{n}},{\mathfrak{r}})=(1),\\ 0&({\mathfrak{n}},{\mathfrak{r}})\neq(1).\end{cases}

Thus,

N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)N𝔫log(QN𝔫)=𝔡𝒟𝔯1N𝔡N𝔪QN𝔡μk(𝔪)N𝔪log(QN𝔪N𝔡).\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{{\mathrm{N}}{\mathfrak{n}}}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}})=\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}\sum_{{\mathrm{N}}{\mathfrak{m}}\leq\frac{Q}{{\mathrm{N}}{\mathfrak{d}}}}\frac{\mu_{k}({\mathfrak{m}})}{{\mathrm{N}}{\mathfrak{m}}}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{d}}}).

By (3.2) and (3.3) in Lemma 3.9, the above is equal to

=\displaystyle= 𝔡𝒟𝔯N𝔡Q1N𝔡(1sk+(QN𝔡)β01(β01)2ζk(β0)+OA((log2QN𝔡)A))\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{d}}\leq Q\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}(\frac{1}{s_{k}}+\frac{(\frac{Q}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}+O_{A}((\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A}))
=\displaystyle= 1sk𝔡𝒟𝔯1N𝔡+𝔡𝒟𝔯N𝔡β0(β01)2ζk(β0)Qβ01\displaystyle\frac{1}{s_{k}}\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}+\frac{\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{-\beta_{0}}}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}Q^{\beta_{0}-1}
+O(𝔡𝒟𝔯N𝔡>Q1N𝔡)+O(𝔡𝒟𝔯N𝔡>QN𝔡β0(β01)2ζk(β0)Qβ01)+OA(𝔡𝒟𝔯N𝔡Q1N𝔡(log2QN𝔡)A).\displaystyle+O(\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{d}}>Q\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}})+O(\frac{\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{d}}>Q\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{-\beta_{0}}}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}Q^{\beta_{0}-1})+O_{A}(\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{d}}\leq Q\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}(\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A}).

Here the first term is equal to N𝔯skφ(𝔯)\frac{{\mathrm{N}}{\mathfrak{r}}}{s_{k}\varphi({\mathfrak{r}})}. Let

C𝔯,β0=𝔡𝒟𝔯N𝔡β0(β01)2ζk(β0).C_{{\mathfrak{r}},\beta_{0}}=\frac{\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{-\beta_{0}}}{(\beta_{0}-1)^{2}\zeta_{k}^{{}^{\prime}}(\beta_{0})}.

Recall the definition of σa(𝔫)\sigma_{a}({\mathfrak{n}}) in Section 2. Note that for (𝔫,𝔪)=(1)({\mathfrak{n}},{\mathfrak{m}})=(1), we have

σa(𝔫𝔪)=σa(𝔫)σa(𝔪).\sigma_{a}({\mathfrak{n}}{\mathfrak{m}})=\sigma_{a}({\mathfrak{n}})\sigma_{a}({\mathfrak{m}}).

Then the first error term in (6) is

(6.11) \displaystyle\ll Q1/3𝔡𝒟𝔯N𝔡2/3=Q1/3𝔭|𝔯(1+(N𝔭2/31)1)Q1/3𝔭|𝔯(1+N𝔭1/2)\displaystyle Q^{-1/3}\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}{\mathrm{N}}{\mathfrak{d}}^{-2/3}=Q^{-1/3}\prod_{{\mathfrak{p}}|{\mathfrak{r}}}(1+({\mathrm{N}}{\mathfrak{p}}^{2/3}-1)^{-1})\ll Q^{-1/3}\prod_{{\mathfrak{p}}|{\mathfrak{r}}}(1+{\mathrm{N}}{\mathfrak{p}}^{-1/2})
A\displaystyle\ll_{A} (log2Q)Aσ1/2(𝔯)\displaystyle(\log 2Q)^{-A}\sigma_{-1/2}({\mathfrak{r}})

for all but finitely many 𝔭{\mathfrak{p}}. Similarly, for the second error term in (6), it is bounded by

A1(β01)2|ζk(β0)|(log2Q)Aσ1/2(𝔯).\ll_{A}\frac{1}{(\beta_{0}-1)^{2}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}(\log 2Q)^{-A}\sigma_{-1/2}({\mathfrak{r}}).

For the third error term in (6), we separate the sum as

𝔡𝒟𝔯N𝔡Q1N𝔡(log2QN𝔡)A\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{d}}\leq Q\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}(\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A} =\displaystyle= 𝔡𝒟𝔯N𝔡Q1/21N𝔡(log2QN𝔡)A+𝔡𝒟𝔯Q1/2<N𝔡Q1N𝔡(log2QN𝔡)A\displaystyle\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ {\mathrm{N}}{\mathfrak{d}}\leq Q^{1/2}\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}(\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A}+\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\\ Q^{1/2}<{\mathrm{N}}{\mathfrak{d}}\leq Q\end{subarray}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}}(\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A}
\displaystyle\ll (log2Q)A𝔡𝒟𝔯N𝔡1+Q1/6𝔡𝒟𝔯N𝔡2/3\displaystyle(\log 2Q)^{-A}\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}{\mathrm{N}}{\mathfrak{d}}^{-1}+Q^{-1/6}\sum_{{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}}{\mathrm{N}}{\mathfrak{d}}^{-2/3}
\displaystyle\ll (log2Q)Aσ1/2(𝔯).\displaystyle(\log 2Q)^{-A}\sigma_{-1/2}({\mathfrak{r}}).

Note also that using the approach in (6.11), we have

|C𝔯,β0|=𝔡𝒟𝔯N𝔡β0(β01)2|ζk(β0)|σ12(𝔯)(β01)2|ζk(β0)|.|C_{{\mathfrak{r}},\beta_{0}}|=\frac{\sum_{\begin{subarray}{c}{\mathfrak{d}}\in{\mathcal{D}}_{\mathfrak{r}}\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{-\beta_{0}}}{(\beta_{0}-1)^{2}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}\ll\frac{\sigma_{-\frac{1}{2}}({\mathfrak{r}})}{(\beta_{0}-1)^{2}|\zeta_{k}^{{}^{\prime}}(\beta_{0})|}.

This finishes the proof of Lemma 3.10. ∎

Proof of Lemma 3.11.

We first prove the following formula. For any ideal 𝔫{\mathfrak{n}},

1κ(𝔫)=1N𝔫𝔡|𝔫μk(𝔡)κ(𝔡).\frac{1}{\kappa({\mathfrak{n}})}=\frac{1}{{\mathrm{N}}{\mathfrak{n}}}\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\frac{\mu_{k}({\mathfrak{d}})}{\kappa({\mathfrak{d}})}.

It holds because

1N𝔫𝔡|𝔫μk(𝔡)κ(𝔡)=1N𝔫𝔡|𝔫μk(𝔡)𝔭|𝔡1N𝔭+1=1N𝔫𝔭|𝔫(11N𝔭+1)=1κ(𝔫).\frac{1}{{\mathrm{N}}{\mathfrak{n}}}\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\frac{\mu_{k}({\mathfrak{d}})}{\kappa({\mathfrak{d}})}=\frac{1}{{\mathrm{N}}{\mathfrak{n}}}\sum_{{\mathfrak{d}}|{\mathfrak{n}}}\mu_{k}({\mathfrak{d}})\prod_{{\mathfrak{p}}|{\mathfrak{d}}}\frac{1}{{\mathrm{N}}{\mathfrak{p}}+1}=\frac{1}{{\mathrm{N}}{\mathfrak{n}}}\prod_{{\mathfrak{p}}|{\mathfrak{n}}}(1-\frac{1}{{\mathrm{N}}{\mathfrak{p}}+1})=\frac{1}{\kappa({\mathfrak{n}})}.

Then we are able to compute the left-hand side as

(6.12) N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)log(QN𝔫)\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}}) =\displaystyle= N𝔡Q(𝔡,𝔯)=(1)μk(𝔡)κ(𝔡)N𝔫Q(𝔫,𝔯)=(1)𝔡|𝔫μk(𝔫)N𝔫log(QN𝔫)\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{d}}\leq Q\\ ({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{d}})}{\kappa({\mathfrak{d}})}\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\\ {\mathfrak{d}}|{\mathfrak{n}}\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{{\mathrm{N}}{\mathfrak{n}}}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}})
=\displaystyle= N𝔡Q(𝔡,𝔯)=(1)μk2(𝔡)N𝔡κ(𝔡)N𝔪QN𝔡(𝔪,𝔡𝔯)=(1)μk(𝔪)N𝔪log(QN𝔪N𝔡).\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{d}}\leq Q\\ ({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}^{2}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}\kappa({\mathfrak{d}})}\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{m}}\leq\frac{Q}{{\mathrm{N}}{\mathfrak{d}}}\\ ({\mathfrak{m}},{\mathfrak{d}}{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{m}})}{{\mathrm{N}}{\mathfrak{m}}}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{m}}{\mathrm{N}}{\mathfrak{d}}}).

By Lemma 3.10, (6.12) is equal to

=\displaystyle= N𝔯skφ(𝔯)N𝔡Q(𝔡,𝔯)=(1)μk2(𝔡)κ(𝔡)φ(𝔡)+N𝔡Q(𝔡,𝔯)=(1)C𝔡𝔯,β0μk2(𝔡)N𝔡κ(𝔡)(QN𝔡)β01\displaystyle\frac{{\mathrm{N}}{\mathfrak{r}}}{s_{k}\varphi({\mathfrak{r}})}\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{d}}\leq Q\\ ({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}^{2}({\mathfrak{d}})}{\kappa({\mathfrak{d}})\varphi({\mathfrak{d}})}+\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{d}}\leq Q\\ ({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}C_{{\mathfrak{d}}{\mathfrak{r}},\beta_{0}}\frac{\mu_{k}^{2}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}\kappa({\mathfrak{d}})}(\frac{Q}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}
+OA(Cβ0σ12(𝔯)dQN𝔡2(log2QN𝔡)A)\displaystyle+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})\sum_{d\leq Q}{\mathrm{N}}{\mathfrak{d}}^{-2}(\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A})
=\displaystyle= N𝔯skφ(𝔯)𝔭𝔯(1N𝔭2)1+(𝔡,𝔯)=(1)C𝔡𝔯,β0μk2(𝔡)N𝔡κ(𝔡)(QN𝔡)β01\displaystyle\frac{{\mathrm{N}}{\mathfrak{r}}}{s_{k}\varphi({\mathfrak{r}})}\prod_{{\mathfrak{p}}\nmid{\mathfrak{r}}}(1-{\mathrm{N}}{\mathfrak{p}}^{-2})^{-1}+\sum_{\begin{subarray}{c}({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}C_{{\mathfrak{d}}{\mathfrak{r}},\beta_{0}}\frac{\mu_{k}^{2}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}\kappa({\mathfrak{d}})}(\frac{Q}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}
+O(N𝔯φ(𝔯)N𝔡>QN𝔡2)+OA(Cβ0σ12(𝔯)dQN𝔡2(log2QN𝔡)A)\displaystyle+O(\frac{{\mathrm{N}}{\mathfrak{r}}}{\varphi({\mathfrak{r}})}\sum_{{\mathrm{N}}{\mathfrak{d}}>Q}{\mathrm{N}}{\mathfrak{d}}^{-2})+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})\sum_{d\leq Q}{\mathrm{N}}{\mathfrak{d}}^{-2}(\log\frac{2Q}{{\mathrm{N}}{\mathfrak{d}}})^{-A})
=\displaystyle= κ(𝔯)N𝔯ζk(2)sk+C𝔯,β0Qβ01+OA(Cβ0σ12(𝔯)(log2Q)A)\displaystyle\frac{\kappa({\mathfrak{r}})}{{\mathrm{N}}{\mathfrak{r}}}\frac{\zeta_{k}(2)}{s_{k}}+C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-A})

for a constant C𝔯,β0C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}} depending only on 𝔯,β0{\mathfrak{r}},\beta_{0}.

Note also that

|C𝔯,β0|\displaystyle|C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}| =\displaystyle= |(𝔡,𝔯)=(1)C𝔡𝔯,β0μk2(𝔡)N𝔡κ(𝔡)(1N𝔡)β01|(𝔡,𝔯)=(1)|C𝔡𝔯,β0|1N𝔡2(1N𝔡)β01\displaystyle\left|\sum_{\begin{subarray}{c}({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}C_{{\mathfrak{d}}{\mathfrak{r}},\beta_{0}}\frac{\mu_{k}^{2}({\mathfrak{d}})}{{\mathrm{N}}{\mathfrak{d}}\kappa({\mathfrak{d}})}(\frac{1}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}\right|\leq\sum_{\begin{subarray}{c}({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}|C_{{\mathfrak{d}}{\mathfrak{r}},\beta_{0}}|\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2}}(\frac{1}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}
\displaystyle\leq (𝔡,𝔯)=(1)|Cβ0σ12(𝔡𝔯)|1N𝔡2(1N𝔡)β01=Cβ0σ12(𝔯)(𝔡,𝔯)=(1)σ12(𝔡)1N𝔡2(1N𝔡)β01\displaystyle\sum_{\begin{subarray}{c}({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}|C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{d}}{\mathfrak{r}})|\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2}}(\frac{1}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}=C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})\sum_{\begin{subarray}{c}({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}\sigma_{-\frac{1}{2}}({\mathfrak{d}})\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2}}(\frac{1}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}
\displaystyle\ll Cβ0σ12(𝔯)(𝔡,𝔯)=(1)N𝔡121N𝔡2(1N𝔡)β01Cβ0σ12(𝔯).\displaystyle C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})\sum_{\begin{subarray}{c}({\mathfrak{d}},{\mathfrak{r}})=(1)\end{subarray}}{\mathrm{N}}{\mathfrak{d}}^{\frac{1}{2}}\frac{1}{{\mathrm{N}}{\mathfrak{d}}^{2}}(\frac{1}{{\mathrm{N}}{\mathfrak{d}}})^{\beta_{0}-1}\ll C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}}).

This finishes the proof of Lemma 3.11. ∎

Proof of Lemma 3.12.

For any constant c>1c>1,

(logc)N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)\displaystyle(\log c)\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})} =\displaystyle= N𝔫Qc(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)log(QcN𝔫)N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)log(QN𝔫)\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Qc\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})}\log(\frac{Qc}{{\mathrm{N}}{\mathfrak{n}}})-\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})}\log(\frac{Q}{{\mathrm{N}}{\mathfrak{n}}})
Q<N𝔫Qc(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)log(QcN𝔫).\displaystyle-\sum_{\begin{subarray}{c}Q<{\mathrm{N}}{\mathfrak{n}}\leq Qc\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})}\log(\frac{Qc}{{\mathrm{N}}{\mathfrak{n}}}).

We take c=1+(log2Q)Aexp((log2Q)A)c=1+(\log 2Q)^{-A}\asymp\exp((\log 2Q)^{-A}). By Lemma 3.11, the first two sums on the right-hand side is

=\displaystyle= C𝔯,β0Qβ01((1+(log2Q)A)β011)+OA(Cβ0σ12(𝔯)(log2Q)2A)\displaystyle C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}((1+(\log 2Q)^{-A})^{\beta_{0}-1}-1)+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-2A})
=\displaystyle= O(C𝔯,β0Qβ01|exp((β01)(log2Q)A)1|)+OA(Cβ0σ12(𝔯)(log2Q)2A)\displaystyle O(C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}|\exp((\beta_{0}-1)(\log 2Q)^{-A})-1|)+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-2A})
=\displaystyle= O(C𝔯,β0Qβ01(1β0)(log2Q)A)+OA(Cβ0σ12(𝔯)(log2Q)2A).\displaystyle O(C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}(1-\beta_{0})(\log 2Q)^{-A})+O_{A}(C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-2A}).

The third sum is (logc)Q<N𝔫QcN𝔫1(logc)2\ll(\log c)\sum_{Q<{\mathrm{N}}{\mathfrak{n}}\leq Qc}{\mathrm{N}}{\mathfrak{n}}^{-1}\ll(\log c)^{2}. Therefore,

N𝔫Q(𝔫,𝔯)=(1)μk(𝔫)κ(𝔫)\displaystyle\sum_{\begin{subarray}{c}{\mathrm{N}}{\mathfrak{n}}\leq Q\\ ({\mathfrak{n}},{\mathfrak{r}})=(1)\end{subarray}}\frac{\mu_{k}({\mathfrak{n}})}{\kappa({\mathfrak{n}})} A\displaystyle\ll_{A} C𝔯,β0Qβ01(1β0)(log2Q)Alogc+Cβ0σ12(𝔯)(log2Q)2Alogc+logc\displaystyle\frac{C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}(1-\beta_{0})(\log 2Q)^{-A}}{\log c}+C_{\beta_{0}}^{{}^{\prime}}\frac{\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-2A}}{\log c}+\log c
\displaystyle\asymp C𝔯,β0Qβ01(1β0)+Cβ0σ12(𝔯)(log2Q)A+(log2Q)A\displaystyle C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}(1-\beta_{0})+C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-A}+(\log 2Q)^{-A}
\displaystyle\asymp C𝔯,β0Qβ01(1β0)+Cβ0σ12(𝔯)(log2Q)A.\displaystyle C_{{\mathfrak{r}},\beta_{0}}^{{}^{\prime}}Q^{\beta_{0}-1}(1-\beta_{0})+C_{\beta_{0}}^{{}^{\prime}}\sigma_{-\frac{1}{2}}({\mathfrak{r}})(\log 2Q)^{-A}.

This completes the proofs of all lemmas in Section 3 and hence Theorems 1.3 and 1.1, and Corollary 1.2 are proved.

Acknowledgements

The contents in this paper are part of the author’s Ph.D. dissertation at Duke University. The author thanks his advisor Lillian Pierce for her helpful and consistent guidance during this work, and Jesse Thorner for suggesting this topic.

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