On ${}_5ψ_5$ identities of Bailey
Aritram Dhar
TL;DR
The paper analyzes Bailey's bilateral summations ${}_5\psi_5$ by deriving two identities from Carlitz's terminating ${}_5\phi_4$ through even/odd parameter substitutions, then shows that in the limit $n\to\infty$ these yield two ${}_3\psi_3$ summations with explicit infinite-product forms. It further provides Ismail-type proofs of these ${}_3\psi_3$ identities by recasting them as finite ${}_3\phi_2$ sums and employing analytic continuation arguments inspired by Ramanujan's ${}_1\psi_1$ and Bailey's ${}_6\psi_6$ framework. The work highlights a deep connection between bilateral and unilateral basic hypergeometric series and demonstrates how Carlitz-type and Ismail-style techniques complement each other to establish exact summations. The results extend Bailey's identities, offering multiple corroborating pathways (finite ${}_5\phi_4$ transforms and infinite ${}_3\psi_3$ products) with potential applications in related areas of basic hypergeometric analysis and $q$-series theory.
Abstract
In this paper, we provide proofs of two ${}_5ψ_5$ summation formulas of Bailey using a ${}_5φ_4$ identity of Carlitz. We show that in the limiting case, the two ${}_5ψ_5$ identities give rise to two ${}_3ψ_3$ summation formulas of Bailey. Finally, we prove the two ${}_3ψ_3$ identities using a technique initially used by Ismail to prove Ramanujan's ${}_1ψ_1$ summation formula and later by Ismail and Askey to prove Bailey's very-well-poised ${}_6ψ_6$ sum.
