arXiv subjects

Pieter Moree

Publications and source records attributed to Pieter Moree.

At least 19 recordsLinked to original sources

arXiv2026

Beyond the Riemann Hypothesis bounds: A pair-correlation approach to the least prime in arithmetic progression and the smallest quadratic non-residue

The Generalized Riemann Hypothesis (GRH) has long defined the expected bounds for the smallest prime in an arithmetic progression and the least quadratic non-residue. However, this hypothesis primarily addresses the horizontal location of non-trivial zeros. In this paper, we show that incorporating the vertical spacing--or pair-correlation--of these zeros allows us to surpass these classical bounds. By combining these two zero-distribution perspectives, we establish sharper estimates for both problems under GRH and specific pair-correlation hypotheses, thereby providing a new link between pair-correlation phenomena for Dirichlet L-functions and these two classical problems.

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arXiv2025

Counting ideals in abelian number fields

Already Dedekind and Weber considered the problem of counting integral ideals of norm at most $x$ in a given number field $K$. Here we improve on the existing results in case $K/\mathbb Q$ is abelian and has degree at least four. For these fields, we obtain as a consequence an improvement of the available results on counting pairs of coprime ideals each having norm at most $x$.

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arXiv2024

Euler-Kronecker constants of modular forms: beyond Dirichlet $L$-series

The Euler-Kronecker constants related to congruences of Fourier coefficients of modular forms that have been computed so far, involve logarithmic derivatives of Dirichlet $L$-series as most complicated functions (to the best of our knowledge). However, generically the more complicated Artin $L$-series will make their appearance. Here we work out some simple examples involving an Artin $L$-series related to an ${\mathfrak S}_3$, respectively~${\mathfrak S}_4$ extension. These examples are related to a mod-2 congruence for $X_0(11)$, respectively a mod-59 congruence for $\Delta E_4$ conjectured by Serre and Swinnerton-Dyer and proved by Haberland. The latter example solves a problem posed by Ciolan, Languasco and the third author in 2023.

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arXiv2024

Pair Correlation of zeros of Dirichlet $L$-Functions: A possible path towards the conjectures of Chowla, Elliott-Halberstam and Montgomery

Assuming the Generalized Riemann Hypothesis and a pair correlation conjecture for the zeros of Dirichlet $L$-functions, we establish the truth of a conjecture of Montgomery (in its corrected form stated by Friedlander and Granville) on the magnitude of the error term in the prime number theorem in arithmetic progressions. As a consequence, we obtain that, under the same assumptions, the Elliott-Halberstam conjecture holds true. As another consequence, under the same assumptions, we will show that the number of Dirichlet characters $\chi \pmod{q}$ for which $L(\frac{1}{2},\chi)=0$ is of order less than $q^{1/2+\epsilon}$.

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arXiv2024

Sums of two squares and the tau-function: Ramanujan's trail

Ramanujan, in his famous first letter to Hardy, claimed a very precise estimate for the number of integers that can be written as a sum of two squares. Far less well-known is that he also made further claims of a similar nature for the non-divisibility of the Ramanujan tau-function for certain primes. In this survey, we provide more historical details and also discuss related later developments. These show that, as so often, Ramanujan was an explorer in a fascinating wilderness, leaving behind him a beckoning trail.

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arXiv2024

Relative class numbers and Euler-Kronecker constants of maximal real cyclotomic subfields

The Euler--Kronecker constant of a number field $K$ is the ratio of the constant and the residue of the Laurent series of the Dedekind zeta function $\zeta_K(s)$ at $s=1$. We study the distribution of the Euler--Kronecker constant $\gamma_q^+$ of the maximal real subfield of $\mathbb Q(\zeta_q)$ as $q$ ranges over the primes. Further, we consider the distribution of $\gamma_q^+-\gamma_q$, with $\gamma_q$ the Euler--Kronecker constant of $\mathbb Q(\zeta_q)$ and show how it is connected with Kummer's conjecture, which predicts the asymptotic growth of the relative class number of $\mathbb Q(\zeta_q)$. We improve, for example, the known results on the bounds on average for the Kummer ratio and we prove analogous sharp bounds for $\gamma_q^+-\gamma_q$. The methods employed are partly inspired by those used by Granville (1990) and Croot and Granville (2002) to investigate Kummer's conjecture. We supplement our theoretical findings with numerical illustrations to reinforce our conclusions.

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arXiv2024

Euler constants from primes in arithmetic progression

Many Dirichlet series of number theoretic interest can be written as a product of generating series $\zeta_{\,d,a}(s)=\prod\limits_{p\equiv a\pmod{d}}(1-p^{-s})^{-1}$, with $p$ ranging over all the primes in the primitive residue class modulo $a\pmod{d}$, and a function $H(s)$ well-behaved around $s=1$. In such a case the corresponding Euler constant can be expressed in terms of the Euler constants $\gamma(d,a)$ of the series $\zeta_{\,d,a}(s)$ involved and the (numerically more harmless) term $H'(1)/H(1)$. Here we systematically study $\gamma(d,a)$, their numerical evaluation and discuss some examples.

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arXiv2024

The Kummer ratio of the relative class number for prime cyclotomic fields

Kummer's conjecture predicts the asymptotic growth of the relative class number of prime cyclotomic fields. We substantially improve the known bounds of Kummer's ratio under three scenarios: no Siegel zero, presence of Siegel zero and assuming the Riemann Hypothesis for the Dirichlet $L$-series attached to odd characters only. The numerical work in this paper extends and improves on our earlier preprint (arXiv:1908.01152) and demonstrates our theoretical results.

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arXiv2024

The Brauer-Siegel ratio for prime cyclotomic fields

The Brauer-Siegel theorem concerns the size of the product of the class number and the regulator of a number field $K$. We derive bounds for this product in case $K$ is a prime cyclotomic field, distinguishing between whether there is a Siegel zero or not. In particular, we make a result of Tatuzawa (1953) more explicit. Our theoretical advancements are complemented by numerical illustrations that are consistent with our findings.

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arXiv2023

On the discriminator of Lucas sequences. II

The family of Shallit sequences consists of the Lucas sequences satisfying the recurrence $U_{n+2}(k)=(4k+2)U_{n+1}(k) -U_n(k),$ with initial values $U_0(k)=0$ and $U_1(k)=1$ and with $k\ge 1$ arbitrary. For every fixed $k$ the integers $\{U_n(k)\}_{n\ge 0}$ are distinct, and hence for every $n\ge 1$ there exists a smallest integer $D_k(n)$, called discriminator, such that $U_0(k),U_1(k),\ldots,U_{n-1}(k)$ are pairwise incongruent modulo $D_k(n).$ In part I it was proved that there exists a constant $n_k$ such that $D_{k}(n)$ has a simple characterization for every $n\ge n_k$. Here, we study the values not following this characterization and provide an upper bound for $n_k$ using Matveev's theorem and the Koksma-Erdos-Turán inequality. We completely determine the discriminator $D_{k}(n)$ for every $n\ge 1$ and a set of integers $k$ of natural density $68/75$. We also correct an omission in the statement of Theorem 3 in part I.

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arXiv2023

Sequences of integers generated by two fixed primes

Let $p$ and $q$ be two distinct fixed prime numbers and $(n_i)_{i\geq 0}$ the sequence of consecutive integers of the form $p^a\cdot q^b$ with $a,b\ge 0$. Tijdeman gave a lower bound (1973) and an upper bound (1974) for the gap size $n_{i+1}-n_i$, with each bound containing an unspecified exponent and implicit constant. We will explicitly bound these four quantities. Earlier Langevin (1976) gave weaker estimates for (only) the exponents. Given a real number $\alpha>1$, there exists a smallest number $m$ such that for every $n\ge m$, there exists an integer $n_i$ in $[n,n\alpha)$. Our effective version of Tijdeman's result immediately implies an upper bound for $m$, which using the Koksma-Erd\H{o}s-Turan inequality we will improve on. We present a fast algorithm to determine $m$ when $\max\{p,q\}$ is not too large and demonstrate it with numerical material. In an appendix we explain, given $n_i$, how to efficiently determine both $n_{i-1}$ and $n_{i+1}$, something closely related to work of B\'erczes, Dujella and Hajdu.

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arXiv2023

Irreducibility of the Koopman representations for the group ${\rm GL}_0(2\infty,{\mathbb R})$ acting on three infinite rows

Consider the inductive limit of the general linear groups ${\rm GL}_0(2\infty,{\mathbb R})$ $= \varinjlim_{n}{\rm GL}(2n-1,{\mathbb R})$, acting on the space $X_m$ of $m$ rows, infinite in both directions, with Gaussian measure. This measure is the infinite tensor product of one-dimensional arbitrary Gaussian non-centered measures. In this article we prove an irreducibility criterion for $m=3$. In 2019, the first author [28] established a criterion for $m\le 2$. Our proof is in the same spirit, but the details are far more involved.

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arXiv2023

A proof of the corrected Sister Beiter cyclotomic coefficient conjecture inspired by Zhao and Zhang

The largest coefficient (in absolute value) of a cyclotomic polynomial $Φ_n$ is called its height $A(n)$. In case $p$ is a fixed prime it turns out that as $q$ and $r$ range over all primes satisfying $p<q<r$, the height $A(pqr)$ assumes a maximum $M(p)$. In 1968, Sister Marion Beiter conjectured that $M(p)\leq (p+1)/2$. In 2009, this was disproved for every $p\ge 11$ by Yves Gallot and Pieter Moree. They proposed a Corrected Beiter Conjecture, namely $M(p)\leq 2p/3$. In 2009, Jia Zhao and Xianke Zhang posted on the arXiv what they thought to be a proof of this conjecture. Their work was never accepted for publication in a journal. However, in retrospect it turns out to be essentially correct, but rather sketchy at some points. Here we supply a lot more details. \par The bound $M(p)\le 2p/3$ allows us to improve some bounds of Bzdęga from 2010 for ternary cyclotomic coefficients. It also makes it possible to determine $M(p)$ exactly for three new primes $p$ and study the fine structure of $A(pqr)$ for them in greater detail.

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arXiv2023

The distribution of the multiplicative index of algebraic numbers over residue classes

Let $K$ be a number field and $G$ a finitely generated torsion-free subgroup of $K^\times$. Given a prime $\mathfrak p$ of $K$ we denote by ${\rm ind}_{\mathfrak p}(G)$ the index of the subgroup $(G\bmod\mathfrak p)$ of the multiplicative group of the residue field at $\mathfrak p$. Under the Generalized Riemann Hypothesis we determine the natural density of primes of $K$ for which this index is in a prescribed set $S$ and has prescribed Frobenius in a finite Galois extension $F$ of $K$. We study in detail the natural density in case $S$ is an arithmetic progression, in particular its positivity.

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arXiv2022

Ramanujan-style congruences for prime level

We establish Ramanujan-style congruences modulo certain primes $\ell$ between an Eisenstein series of weight $k$, prime level $p$ and a cuspidal newform in the $\varepsilon$-eigenspace of the Atkin-Lehner operator inside the space of cusp forms of weight $k$ for $Γ_0(p)$. Under a mild assumption, this refines a result of Gaba-Popa. We use these congruences and recent work of Ciolan, Languasco and the third author on Euler-Kronecker constants, to quantify the non-divisibility of the Fourier coefficients involved by $\ell.$ The degree of the number field generated by these coefficients we investigate using recent results on prime factors of shifted prime numbers.

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arXiv2022

Prime divisors of $\ell$-Genocchi numbers and the ubiquity of Ramanujan-style congruences of level $\ell$

Let $\ell$ be any fixed prime number. We define the $\ell$-Genocchi numbers by $G_n:=\ell(1-\ell^n)B_n$, with $B_n$ the $n$-th Bernoulli number. They are integers. We introduce and study a variant of Kummer's notion of regularity of primes. We say that an odd prime $p$ is $\ell$-Genocchi irregular if it divides at least one of the $\ell$-Genocchi numbers $G_2,G_4,\ldots, G_{p-3}$, and $\ell$-regular otherwise. With the help of techniques used in the study of Artin's primitive root conjecture, we give asymptotic estimates for the number of $\ell$-Genocchi irregular primes in a prescribed arithmetic progression in case $\ell$ is odd. The case $\ell=2$ was already dealt with by Hu, Kim, Moree and Sha (2019). Using similar methods we study the prime factors of $(1-\ell^n)B_{2n}/2n$ and $(1+\ell^n)B_{2n}/2n$. This allows us to estimate the number of primes $p\leq x$ for which there exist modulo $p$ Ramanujan-style congruences between the Fourier coefficients of an Eisenstein series and some cusp form of prime level $\ell$.

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arXiv2022

Higher Reciprocity Laws and Ternary Linear Recurrence Sequences

We describe the set of prime numbers splitting completely in the non-abelian splitting field of certain monic irreducible polynomials of degree three. As an application we establish some divisibility properties of the associated ternary recurrence sequence by primes $p$, thus greatly extending recent work of Evink and Helminck and of Faisant. We also prove some new results on the number of solutions of the characteristic equation of the recurrence sequence modulo $p,$ extending and simplifying earlier work of Zhi-Hong Sun (2003).

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arXiv2021

Landau and Ramanujan approximations for divisor sums and coefficients of cusp forms

In 1961, Rankin determined the asymptotic behavior of the number $S_{k,q}(x)$ of positive integers $n\le x$ for which a given prime $q$ does not divide $\sigma_k(n),$ the $k$-th divisor sum function. By computing the associated Euler-Kronecker constant $\gamma_{k,q},$ which depends on the arithmetic of certain subfields of $\mathbb Q(\zeta_q)$, we obtain the second order term in the asymptotic expansion of $S_{k,q}(x).$ Using a method developed by Ford, Luca and Moree (2014), we determine the pairs $(k,q)$ with $(k, q-1)=1$ for which Ramanujan's approximation to $S_{k,q}(x)$ is better than Landau's. This entails checking whether $\gamma_{k,q}<1/2$ or not, and requires a substantial computational number theoretic input and extensive computer usage. We apply our results to study the non-divisibility of Fourier coefficients of six cusp forms by certain exceptional primes, extending the earlier work of Moree (2004), who disproved several claims made by Ramanujan on the non-divisibility of the Ramanujan tau function by five such exceptional primes.

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