Multiple Rogers-Ramanujan type identities for inert quadratic orders

TL;DR

This paper proves a conjecture relating complex multisums and Bressoud sums for inert quadratic orders, revealing surprising parameter independence and proposing a refined interpolating multisum for Quot zeta functions.

Contribution

It establishes a new identity connecting multisums and Bressoud sums for inert quadratic orders, confirming a recent conjecture and generalizing multisums with a novel parameter.

Findings

Proved the equality between a 2m-fold multisum and an m-fold Bressoud sum.

Showed the multisum's $a$-generalization is $a$-independent using $q$-theoretic methods.

Proposed a refined multisum interpolating Quot zeta functions for quadratic orders.

Abstract

We compute the Quot and finitized Coh zeta functions of the inert quadratic orders $\mathbb{F}_q[[T]]+T^{m}\mathbb{F}_{q^{2}}[[T]]$ for every $m\geq 1$ in terms of a $2m$-fold multisum, and then show this multisum equals an $m$-fold Bressoud sum. This proves a recent conjecture of the second author, rounding up the line of exploration in the series of work by the authors and Jiang. The equality between the $2m$-fold multisum and the $m$-fold Bressoud sum is built upon generalizing the multisum by introducing a ``ghost'' parameter $a$ to its summands. We then show that such an $a$-generalization is surprisingly $a$-independent by purely $q$-theoretic techniques. Finally, we propose a refined multisum that interpolates two versions of Quot zeta functions for all three types of quadratic orders.