Near-integral fusion

TL;DR

This paper studies near-integral fusion rings, generalizing known results on near-group fusion categories, and characterizes when these categories are braided, providing insights into a large class of premodular fusion categories.

Contribution

It extends the theory of near-group fusion categories to near-integral fusion categories and characterizes their braiding properties, including a classification of small rank cases.

Findings

Characterization of when near-integral fusion categories are braided.

Generalization of known results from near-group to near-integral fusion categories.

Classification of over 300 braided equivalence classes of premodular fusion categories of rank ≤6.

Abstract

We abstract the study of irreducible characters of finite groups vanishing on all but two conjugacy classes, initiated by S. Gagola, to irreducible characters of fusion rings whose kernel has maximal rank. These near-integral fusion rings include the near-groups which are currently one of the most abundant sources of novel examples of fusion categories to date. We generalize many of the known results on near-group fusion categories from the literature to near-integral fusion categories and characterize when such categories are braided. In particular, braided near-integral fusion categories describe all braided fusion categories which are almost symmetrically braided. This novel result allows a digestible characterization of the over $300$ braided equivalence classes of premodular fusion categories of rank $6$ or less.