Quantum Theory Seminar
Gauge theories at finite fermion density: avoiding the sign problem in the canonical formulation
Thursday June 8, 2017 14:15:00 CEST
Thursday June 8, 2017 15:15:00 CEST
Prof. Urs Wenger
In this talk I discuss gauge theories at finite fermion density which, in general, suffer from a fermion sign problem. One approach to the sign problem is to use the canonical formulation where the fermion number is fixed. Using Wilson fermions on the lattice the canonical sectors of the theories can be obtained directly from transfer matrices explicitely defined through the fermion Dirac operator. As a first example, I consider supersymmetric SU(N) Yang-Mills theories in 0+1 dimensions and present some results concerning the moduli space of these theories. As a second example, I discuss QCD in the heavy-dense limit and show how the sign problem is avoided in the strong coupling limit. Finally, as a third example, related to heavy-dense QCD, I construct a cluster algorithm for the 3-state Potts model which solves the sign problem completely, even away from the strong coupling limit.