|Speaker:||Junya Yagi (Rutgers University)|
|Title:||Chiral Algebras of (0,2) Models: Beyond Perturbation Theory|
|Date:||Tue, Nov 24, 2009, 13:15 - 14:45|
|Place:||Seminar Room at IPMU Prefab. B|
The chiral algebras of two-dimensional sigma models with (0,2)
supersymmetry are infinite-dimensional generalizations of the chiral
rings of (2,2) models. Perturbatively, they enjoy rich mathematical
structures described by sheaves of chiral differential operators.
Nonperturbatively, however, they vanish completely for certain (0,2)
models with no left-moving fermions. In this talk, I will explain how
this vanishing phenomenon takes places. The vanishing of the chiral
algebra of a (0, 2) model implies that supersymmetry is spontaneously
broken in the model, which in turn suggests that no harmonic spinors
exist on the loop space of the target space. In particular, the
elliptic genus of the model vanishes, thereby providing a physics
proof of a special case of the Hoehn-Stolz conjecture.