Supercurrent flow in NJL2+1 at high baryon density

We present results of numerical simulations of the 2+1d Nambu-Jona-Lasinio model with non-zero baryon chemical potential μ and spatially-varying complex diquark source strength j. By choosing arg(j) to vary smoothly through 2π across the spatial extent of the lattice, a baryon number current is induced which in the high density phase remains non-vanishing as |j|→0; we are hence able to extract a quantity characteristic of a superfluid known as the helicity modulus. We also study supercurrent flow at non-zero temperature and estimate the critical temperature at which the normal phase is restored, which is consistent with the conventional picture for thin-film superfluids in which the transition is viewed in terms of vortex-anti-vortex unbinding.