English

The Newton Polyhedron and positivity of ${}_2F_3$ hypergeometric functions

Classical Analysis and ODEs 2021-02-09 v1

Abstract

As for the 2F3{}_2F_3 hypergeometric function of the form \begin{equation*} {}_2F_3\left[\begin{array}{c} a_1, a_2\\ b_1, b_2, b_3\end{array}\biggr| -x^2\right]\qquad(x>0), \end{equation*} where all of parameters are assumed to be positive, we give sufficient conditions on (b1,b2,b3)(b_1, b_2, b_3) for its positivity in terms of Newton polyhedra with vertices consisting of permutations of (a2,a1+1/2,2a1)\,(a_2, a_1+1/2, 2a_1)\, or (a1,a2+1/2,2a2).\,(a_1, a_2+1/2, 2a_2). As an application, we obtain an extensive validity region of (α,λ,μ)(\alpha, \lambda, \mu) for the inequality \begin{equation*} \int_0^x (x-t)^{\lambda}\, t^{\mu} J_\alpha(t)\, dt \ge 0\qquad(x>0). \end{equation*}

Keywords

Cite

@article{arxiv.2102.04111,
  title  = {The Newton Polyhedron and positivity of ${}_2F_3$ hypergeometric functions},
  author = {Yong-Kum Cho and Seok-Young Chung},
  journal= {arXiv preprint arXiv:2102.04111},
  year   = {2021}
}

Comments

The paper is accepted to <Constructive Approximation>