Counting Salem numbers arising from arithmetic hyperbolic orbifolds

Fuente: arXiv
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Main Authors: Chu, Michelle, Murillo, Plinio G. P., Romero, Otto, Thompson, Lola
Format: Preprint
Published: 2025
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author Chu, Michelle
Murillo, Plinio G. P.
Romero, Otto
Thompson, Lola
author_facet Chu, Michelle
Murillo, Plinio G. P.
Romero, Otto
Thompson, Lola
contents The relationship between Salem numbers and short geodesics has been fruitful in quantitative studies of arithmetic hyperbolic orbifolds, particularly in dimensions 2 and 3. In this article, we push these connections even further. The primary goals are: (1) to bound the proportion of Salem numbers of degree up to $n+1$ in the commensurability class of classical arithmetic lattices in any odd dimension $n$; (2) to improve lower bounds for the strong exponential growth of averages of multiplicities in the geodesic length spectrum of non-compact arithmetic orbifolds. In order to accomplish these goals, we bound, for a fixed square-free integer $D$, the count of Salem numbers with minimal polynomial $f$ satisfying $f(1)f(-1)=-D$ in $\mathbb{Q}^{\times}/\mathbb{Q}^{\times 2}$. To do this, we make use of results on the distribution of Salem numbers, as well as classical methods for counting Pythagorean triples and Gauss' lattice-counting argument. To this end, we give a generalization of the count of Pythagorean triples and provide an elementary proof which may be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2508_08003
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Counting Salem numbers arising from arithmetic hyperbolic orbifolds
Chu, Michelle
Murillo, Plinio G. P.
Romero, Otto
Thompson, Lola
Number Theory
Differential Geometry
Group Theory
Geometric Topology
The relationship between Salem numbers and short geodesics has been fruitful in quantitative studies of arithmetic hyperbolic orbifolds, particularly in dimensions 2 and 3. In this article, we push these connections even further. The primary goals are: (1) to bound the proportion of Salem numbers of degree up to $n+1$ in the commensurability class of classical arithmetic lattices in any odd dimension $n$; (2) to improve lower bounds for the strong exponential growth of averages of multiplicities in the geodesic length spectrum of non-compact arithmetic orbifolds. In order to accomplish these goals, we bound, for a fixed square-free integer $D$, the count of Salem numbers with minimal polynomial $f$ satisfying $f(1)f(-1)=-D$ in $\mathbb{Q}^{\times}/\mathbb{Q}^{\times 2}$. To do this, we make use of results on the distribution of Salem numbers, as well as classical methods for counting Pythagorean triples and Gauss' lattice-counting argument. To this end, we give a generalization of the count of Pythagorean triples and provide an elementary proof which may be of independent interest.
title Counting Salem numbers arising from arithmetic hyperbolic orbifolds
topic Number Theory
Differential Geometry
Group Theory
Geometric Topology
url https://arxiv.org/abs/2508.08003