On the Characters of Parafermionic Field Theories

We study cosets of the type H_l/U(1)^r, where H is any Lie algebra at level l and rank r. These theories are parafermionic and their characters are related to the string functions, which are generating functions for the multiplicities of weights in the affine representations. An identity for the characters is described, which apply to all the algebras and all the levels. The expression is of the Rogers–Ramanujan type. We verify this conjecture, for many algebras and levels, using Freudenthal–Kac formula, which calculates the multiplicities in the affine representations, recursively, up to some grade. Our conjecture encapsulates all the known results about these string functions, along with giving a vast wealth of new ones.