The fermion-bag approach to four-fermion field theories

by Shailesh Chandrasekharan

Monday 30 May 2011, 11:00 → 12:00 Europe/Zurich

TH Theory Conference Room (CERN)

It is well known that the Hybrid Monte Carlo (HMC) method encounters many difficulties in approaching the chiral limit in QCD and other four-fermion field theories including models of Graphene. In this talk we present a new approach to four-fermion field theories. The basic idea is to identify the optimal unpaired fermionic degrees of freedom which lead to sign problems. These degrees of freedom, which resemble a bag in certain parameter regions, are refered to as fermion bags. A resummation of all fermion world lines inside a bag is usually sufficient to solve the sign problem in many interesting cases. This then leads to algorithms that are efficient at both weak and strong couplings even in the chiral limit.