Fermion-bag inspired Hamiltonian lattice field theory for fermionic quantum criticality

Motivated by the fermion-bag approach, we construct a new class of Hamiltonian lattice field theories that can help us to study fermionic quantum critical points, particularly those with four-fermion interactions. Although these theories are constructed in discrete time with a finite temporal lattice spacing epsilon, when epsilon -> 0, conventional continuous-time Hamiltonian lattice field theories are recovered. The fermionbag algorithms run relatively faster when epsilon =1 as compared to epsilon -> 0 but still allow us to compute universal quantities near the quantum critical point even at such a large value of epsilon. As an example of this new approach, here we study the N (f) =1 Gross-Neveu chiral-Ising universality class in 2 + 1 dimensions by calculating the critical scaling of the staggered mass order parameter. We show that we are able to study lattice sizes up to 100(2) sites when epsilon = 1, while with comparable resources we can reach lattice sizes of only up to 64(2) when epsilon -> 0. The critical exponents obtained in both these studies match within errors.