On Nahm's conjecture

Thu, 18/11/2010
16:00
Dr S Zwegers (University College, Dublin) Number Theory Seminar Add to calendar L3
We consider certain q-series depending on parameters (A,B,C), where A is a positive definite r times r matrix, B is a r-vector and C is a scalar, and ask when these q-series are modular forms. Werner Nahm (DIAS) has formulated a partial answer to this question: he conjectured a criterion for which A's can occur, in terms of torsion in the Bloch group. For the case r=1, the conjecture has been show to hold by Don Zagier (MPIM and CdF). For r=2, Masha Vlasenko (MPIM) has recently found a counterexample. In this talk we'll discuss various aspects of Nahm's conjecture.