On the location of the complex conjugate zeros of the partial theta function

Fuente: arXiv
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Main Author: Kostov, Vladimir Petrov
Format: Preprint
Published: 2025
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author Kostov, Vladimir Petrov
author_facet Kostov, Vladimir Petrov
contents We prove that for any $q\in (0,1)$, all complex conjugate pairs of zeros of the partial theta function $θ(q,x):=\sum _{j=0}^{\infty}q^{j(j+1)/2}x^j$ with non-negative real part belong to the half-annulus $\{$Re$(x)\geq 0,~1<|x|<5\}$, where the outer radius cannot be replaced by a number smaller than $e^{π/2}=4.810477382\ldots$, and that for $q\in (0,0.2^{1/4}=0.6687403050\ldots ]$, $θ(q,.)$ has no zeros with non-negative real part. The complex conjugate pairs of zeros with negative real part belong to the left open half-disk of radius $49.8$ centered at the origin.
format Preprint
id arxiv_https___arxiv_org_abs_2501_15866
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the location of the complex conjugate zeros of the partial theta function
Kostov, Vladimir Petrov
Classical Analysis and ODEs
26A06
We prove that for any $q\in (0,1)$, all complex conjugate pairs of zeros of the partial theta function $θ(q,x):=\sum _{j=0}^{\infty}q^{j(j+1)/2}x^j$ with non-negative real part belong to the half-annulus $\{$Re$(x)\geq 0,~1<|x|<5\}$, where the outer radius cannot be replaced by a number smaller than $e^{π/2}=4.810477382\ldots$, and that for $q\in (0,0.2^{1/4}=0.6687403050\ldots ]$, $θ(q,.)$ has no zeros with non-negative real part. The complex conjugate pairs of zeros with negative real part belong to the left open half-disk of radius $49.8$ centered at the origin.
title On the location of the complex conjugate zeros of the partial theta function
topic Classical Analysis and ODEs
26A06
url https://arxiv.org/abs/2501.15866