English

On the Virasoro fusion kernel at $c=25$

High Energy Physics - Theory 2024-08-21 v2 Mathematical Physics math.MP

Abstract

We find a formula for the Virasoro fusion kernel at c=25c=25, in terms of the connection coefficients of the Painlev\'e VI differential equation. Our formula agrees numerically with previously known integral representations of the kernel. The derivation of our formula relies on a duality c26cc\to 26-c that is obeyed by the shift equations for the fusion and modular kernels. We conjecture that for c<1c<1 the fusion and modular kernels are not smooth functions, but distributions.

Cite

@article{arxiv.2310.09334,
  title  = {On the Virasoro fusion kernel at $c=25$},
  author = {Sylvain Ribault and Ioannis Tsiares},
  journal= {arXiv preprint arXiv:2310.09334},
  year   = {2024}
}

Comments

18 pages, plus an ancillary Python notebook -- v2: clarified a few points, discussed the series representation

R2 v1 2026-06-28T12:50:15.603Z