Quantum critical behavior with massless staggered fermions in three dimensions
We report on studies of quantum critical behavior in three dimensional lattice Gross-Neveu models with one flavor of staggered fermions. We focus on two models, one with SU(2)×Z2 symmetry and the other with an SU(2)×U(1) symmetry. Both these models could not be studied earlier with conventional Monte Carlo methods due to sign problems. However, the fermion bag approach is free of sign problems for these models and allows us to compute the critical exponents at the quantum phase transition that separates the massless fermion phase at small couplings and the massive fermion phase at large couplings. Our results help resolve some old puzzles in the field.