Fermion-bag inspired Hamiltonian lattice field theory for fermionic quantum criticality
© 2020 American Physical Society. 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 μ, when μ→0, conventional continuous-time Hamiltonian lattice field theories are recovered. The fermion-bag algorithms run relatively faster when μ=1 as compared to μ→0 but still allow us to compute universal quantities near the quantum critical point even at such a large value of μ. As an example of this new approach, here we study the Nf=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 1002 sites when μ=1, while with comparable resources we can reach lattice sizes of only up to 642 when μ→0. The critical exponents obtained in both these studies match within errors.
Huffman, E; Chandrasekharan, S
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