Umbral Moonshine

Thu, 08/03/2012
15:00
John Duncan Representation Theory Seminar Add to calendar L3
In April 2010 Eguchi–Ooguri–Tachikawa observed a fascinating connection between the elliptic genus of a K3 surface and the largest Mathieu group. We will report on joint work with Miranda Cheng and Jeff Harvey that identifies this connection as one component of a system of surprising relationships between a family of finite groups, their representation theory, and automorphic forms of various kinds Mock modular forms, and particularly their shadows, play a key role in the analysis, and we find several of Ramanujan's mock theta functions appearing as McKay–Thompson series arising from the umbral groups.