Sara Pasquetti gave a talk in the String Theory Seminar at the Mathematical Sciences Institute in Cambridge on 17 January.  The title of the talk was “Holomorphic blocks in 3 dimensions“.  In the talk she showed that sphere partition functions and indices of 3 dimensional, N = 2, gauge theories can be decomposed into a sum of products of a universal set of holomorphic blocks. The blocks count BPS states of a theory on R2 x S1 and are in one-to-one correspondence with the theory’s massive vacua. The blocks turn out to have a wealth of surprising properties such as a Stokes phenomenon and have interesting dual interpretations in analytically continued Chern-Simons theory and open topological strings.