Simulations and Speculations on Gauge Theories with Many Fermions

Simulation data of SU(2) and SU(3) gauge theories with a variable number of flavors ranging from zero to eight are gathered together and new data for the eight-flavor case are presented. The finite-temperature chiral transition is studied on 4×$8^3$ lattices and the critical coupling is recorded as a function of the number of flavors $N_f$. The data exhibit stronger fermion screening as $N_f$ increases and the SU(3) data display a new first-order phase transition at $N_f=8\mathrm{}$.