Chiral symmetry breaking and monopole dynamics in non-compact QED3 coupled to a four-fermi interaction

We present results from the first lattice simulations of three dimensional non-compact quantum electrodynamics (QED3) with Nf four-component fermion flavors coupled to a weak Z2 chirally invariant four-fermi interaction. Results with Nf � 4 show that the scaling near the strong coupling chiral transition or sharp crossover is determined by the 3d Gross-Neveu ultraviolet-stable renormalization group fixed point. Small deviations of the Nf = 4 critical exponents from the respective Gross-Neveu ones, hint at evidence for non-zero fermion mass generated by the gauge fields dynamics that might have been enhanced by the four-fermi coupling. It is also shown that the scaling region is suppressed at weak four-fermi couplings and large Nf values. Measurements of i) a monopole susceptibility which is the polarizability of the monopole configurations, and ii) the density of isolated monopoles, imply that for Nf � 1 and weak gauge couplings the monopoles do not affect the theory’s confining properties, because they are shielded.