A note on trigonometric polynomials for lower bounds of $\zeta(s)$

Non-negative trigonometric polynomials satisfying certain properties are employed when studying a number of aspects of the Riemann zeta function. When establishing zero-free regions in the critical strip, the classical polynomial $3+4\cos(\theta)+\cos(2\theta)$ used by de la Vallée Poussin has since been replaced by more beneficial polynomials with larger degree. The classical polynomial was also employed by Titchmarsh to provide a lower bound on $\abs{\zeta(\sigma+it)}$ when $\sigma>1$. We show that this polynomial is optimal for this purpose.

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Publication Details

Journal
Functiones et Approximatio Commentarii Mathematici
Published
2025-03-14
DOI
https://doi.org/10.7169/facm/240408-31-12
Citations
1
Primary Topic
Analytic Number Theory Research
Type
article
Field-Weighted Citation Impact
5.38
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article

A note on trigonometric polynomials for lower bounds of $\zeta(s)$

Nicol Leong, Michael J. Mossinghoff
1 citations
Functiones et Approximatio Commentarii Mathematici
Analytic Number Theory Research
5.38
article

A note on trigonometric polynomials for lower bounds of $\zeta(s)$

Nicol Leong, Michael J. Mossinghoff
article en
1 citations

Abstract

Non-negative trigonometric polynomials satisfying certain properties are employed when studying a number of aspects of the Riemann zeta function. When establishing zero-free regions in the critical strip, the classical polynomial $3+4\cos(\theta)+\cos(2\theta)$ used by de la Vallée Poussin has since been replaced by more beneficial polynomials with larger degree. The classical polynomial was also employed by Titchmarsh to provide a lower bound on $\abs{\zeta(\sigma+it)}$ when $\sigma>1$. We show that this polynomial is optimal for this purpose.

Functiones et Approximatio Commentarii MathematiciVol. 73(1)
Openalex Percentile: Top 9%
Analytic Number Theory Research
5.38
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