Speaker
Description
Massless chiral fermions can become massive without spontaneous symmetry breaking for a special class of “anomaly-free” interactions. This phenomenon of “symmetric mass generation” (SMG) has been demonstrated numerically on a two-dimensional lattice, for a local discretization with a sine dispersion that doubles the fermion number. Here we demonstrate the effect on a one-dimensional lattice, avoiding the fermion-doubling obstruction by means of a nonlocal discretization that replaces the sine by a tangent. The gapping interaction in the anomaly-free 3–4–5–0 model of Wang and Wen is perturbatively irrelevant, preventing a weak-coupling analysis of the numerical data. We work around this difficulty by including a Hubbard interaction that makes the gapping interaction relevant for Luttinger parameter K < 2/5 ≡ K_c. This makes it possible to stay in the weak coupling regime where SMG can be well described by a scaling analysis. We observe the opening of an excitation gap once K drops below K_c, while the ground state remains nondegenerate — hallmark of the SMG transition.