Rational CFT With Three Characters: The Quasi-Character Approach
Abstract
Quasi-characters are vector-valued modular functions having an integral, but not necessarily positive, q-expansion. Using modular differential equations, a complete classification has been provided in arXiv:1810.09472 for the case of two characters. These in turn generate all possible admissible characters, of arbitrary Wronskian index, in order two. Here we initiate a study of the three-character case. We conjecture several infinite families of quasi-characters and show in examples that their linear combinations an generate admissible characters with arbitrarily large Wronskian index. The structure is completely different from the order two case, and the novel coset construction of arXiv:1602.01022 plays a key role in discovering the appropriate families. Using even unimodular lattices, we construct some explicit three-character CFT corresponding to the new admissible characters.
Cite
@article{arxiv.2002.01949,
title = {Rational CFT With Three Characters: The Quasi-Character Approach},
author = {Sunil Mukhi and Rahul Poddar and Palash Singh},
journal= {arXiv preprint arXiv:2002.01949},
year = {2020}
}
Comments
Typos corrected and references added. Final version, to appear in JHEP, 29 pages