Modular transformations and invariants in the context of fractional level sl̂(2|1;C)

The modular transformation properties of admissible characters of the affine superalgebra sl̂(2|1;C) at fractional level k=1/u−1, u∈N\{1} are presented. All modular invariants for u=2 and u=3 are calculated explicitly and an A-series and D-series of modular invariants emerge.