G. Shibukawa | Searcharxiv

arXiv2026

A degeneration of the generalized Zwegers' $μ$-function according to the Ramanujan difference equation

In this paper, we introduce the little $μ$-function, which is obtained as a degenerate limit of the generalized $μ$-function. We derive the little $μ$-function as the image of the $q$-Borel summation of a divergent solution to the Ramanujan equation which is the most degenerate second order linear $q$-difference equations of Laplace type excluding those of constant coefficients. Moreover, we present several formulas, such as symmetries and connection formulas for the little $μ$-function, similar to those for the generalized $μ$-function. Furthermore, we establish contiguous relations related to the $q,t$-Fibonacci sequences and Wronskian relations involving the Rogers-Ramanujan continued fraction.

math.CA↗

arXiv2025

A generalization of Zwegers' multivariable $μ$-function

We introduce a one parameter deformation of Zwegers' multivariable $μ$-function by applying iterations of the $q$-Borel summation method, which is also a multivariate analogue of the generalized $μ$-function introduced by the authors. For this deformed multivariable $μ$-function, we give some formulas, for example, forward shift formula, translation and $\mathfrak{S}_{N+1}$-symmetry. Further we mention modular formulas for the Zwegers' original multivariable $μ$-function.

math.CA↗