Sara Pasquetti visited the Theoretical Physics group at the Universita degli Studi de Milano-Bicocca. During the visit she gave a seminar on Friday 22 February in the TP seminar. The title is “Holomorphic blocks in three dimensions“. In the talk it is shown 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 × 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 Stokes phenomena and have interesting dual interpretations in analytically continued Chern-Simons theory and open topological strings.