arXiv subjects

Youngju Choie

Publications and source records attributed to Youngju Choie.

3 recordsLinked to original sources

arXiv2021

Formal deformations of the algebra of Jacobi forms and Rankin-Cohen brackets

This work is devoted to the algebraic and arithmetic properties of Rankin-Cohen brackets allowing to define and study them in several natural situations of number theory. It focuses on the property of these brackets to be formal deformations of the algebras on which they are defined, with related questions on restriction-extension methods. The general algebraic results developed here are applied to the study of formal deformations of the algebra of weak Jacobi forms and their relation with the Rankin-Cohen brackets on modular and quasimodular forms.

math.NT↗

arXiv2013

Periods of Jacobi forms and Hecke operator

A Hecke action on the space of periods of cusp forms, which is compatible with that on the space of cusp forms, was first computed using continued fraction and an explicit algebraic formula of Hecke operators acting on the space of period functions of modular forms was derived by studying the rational period functions. As an application an elementary proof of the Eichler-Selberg trace formula was derived. Similar modification has been applied to period space of Maass cusp forms with spectral parameter $s$. In this paper we study the space of period functions of Jacobi forms by means of Jacobi integral and give an explicit description of Hecke operator acting on this space. a Jacobi Eisenstein series $E_{2,1}(τ,z)$ of weight 2 and index 1 is discussed as an example. Periods of Jacobi integrals are already appeared as a disguised form in the work of Zwegers to study Mordell integral coming from Lerch sums and mock Jacobi forms are typical example of Jacobi integral.

math.NT↗

arXiv2010

On Nicolas criterion for the Riemann Hypothesis

Nicolas criterion for the Riemann Hypothesis is based on an inequality that Euler totient function must satisfy at primorial numbers. A natural approach to derive this inequality would be to prove that a specific sequence related to that bound is strictly decreasing. We show that, unfortunately, this latter fact would contradict Cramér conjecture on gaps between consecutive primes. An analogous situation holds when replacing Euler totient by Dedekind $Ψ$ function.

math.NT↗