The elliptic genus of K3 is an index for the 14-BPS states of its σ-model. At the torus orbifold point there is an accidental degeneracy of such states. We blow up the orbifold fixed points using conformal perturbation theory, and find that this fully lifts the accidental degeneracy of the 14-BPS states with h= 1. At a generic point near the Kummer surface the elliptic genus thus measures not just their index, but counts the actual number of these BPS states. We comment on the implication of this for symmetry surfing and Mathieu moonshine.
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Mathematical Physics