Finite-density phase diagram of a (1+1)−d non-abelian lattice gauge theory with tensor networks

Pietro Silvi, Enrique Rico, Marcello Dalmonte, Ferdinand Tschirsich, Simone Montangero
2017 Quantum  
We investigate the finite-density phase diagram of a non-abelian SU(2) lattice gauge theory in (1+1)-dimensions using tensor network methods. We numerically characterise the phase diagram as a function of the matter filling and of the matter-field coupling, identifying different phases, some of them appearing only at finite densities. For weak matter-field coupling we find a meson BCS liquid phase, which is confirmed by second-order analytical perturbation theory. At unit filling and for strong
more » ... coupling, the system undergoes a phase transition to a charge density wave of single-site (spin-0) mesons via spontaneous chiral symmetry breaking. At finite densities, the chiral symmetry is restored almost everywhere, and the meson BCS liquid becomes a simple liquid at strong couplings, with the exception of filling two-thirds, where a charge density wave of mesons spreading over neighbouring sites appears. Finally, we identify two tri-critical points between the chiral and the two liquid phases which are compatible with a SU(2)2 Wess-Zumino-Novikov-Witten model. Here we do not perform the continuum limit but we explicitly address the global U(1) charge conservation symmetry.
doi:10.22331/q-2017-04-25-9 fatcat:kzhip6wa2vhgflu7s2hwkhifgm