Three-dimensional lattice multiflavor scalar chromodynamics: interplay between global and gauge symmetries

We study the nature of the finite-temperature transition of the three-dimensional scalar chromodynamics with N_f flavors. These models are constructed by considering maximally O(M)-symmetric multicomponent scalar models, whose symmetry is partially gauged to obtain SU(N_c) gauge theories, with a residual nonabelian global symmetry given by U(N_f) for N_c>2 and Sp(N_f) for N_c=2, so that M = 2 N_c N_f. We find that their finite-temperature transition is continuous for N_f=2 and for all values of Nc we investigated, N_c=2,3,4. Such continuous transitions belong to universality classes related to the global symmetry group of the theory. For N_c=2 it belongs to the SO(5)=Sp(2)/Z_2 universality class, while for N_c>2 it belongs to the SO(3)=SU(2)/Z_2 universality class. For N_f>2, the transition is always of first order. These results match the predictions obtained by using the effective Landau-Ginzburg-Wilson approach in terms of a gauge-invariant order parameter. Our results indicate that the nonabelian gauge degrees of freedom are irrelevant at the transition. These conclusions are supported by an analysis of gauge-field dependent correlation functions, that are always short-ranged, even at the transition.