HEAVY DYNAMICAL FERMIONS IN LATTICE QCD

It is expected that the only effect of heavy dynamical fermions in QCD is to renormalize the gauge coupling. We derive a simple expression f or the shift in the gauge coupling induced by N(f) flavors of heavy fe rmions. We compare this formula to the shift in the gauge coupling at which the confinement-deconfinement phase transition occurs (at fixed lattice size) from numerical simulations as a function of quark mass a nd N(f). We find remarkable agreement with our expression down to a fa irly light quark mass. However, simulations with eight heavy flavors a nd two light flavors show that the eight flavors do more than just shi ft the gauge coupling. We observe confinement-deconfinement transition s at beta=0 induced by a large number of heavy quarks. We comment on t he relevance of our results to contemporary simulations of QCD which i nclude dynamical fermions.