Microcanonical Fermionic Average Method for Monte Carlo Simulations of Lattice Gauge Theories with Dynamical Fermions

We present a comprehensive exposition of a method for performing numerical simulations of lattice gauge theories with dinamical fermions. Its main aspects have been presented elsewhere. This work is a systematic study of the feasibility of the method, which amounts to separating the evaluation of the fermionic determinant from the generation of gauge configurations through a microcanonical process. The main advantage consists in the fact that the parts of the simulation which are most computer intensive must not be repeated when varying the parameters of the theory. Moreover, we achieve good control over critical slowing down, since the configurations over which the determinant is measured are always very well decorrelated; in addition, the actual implementation of the method allows us to perform simulations at exactly zero fermion mass. We relate the numerical feasibility of this approach to an expansion in the number of flavors; the criteria for its convergence are analyzed both theoretically and in connection with physical problems. On more speculative grounds, we argue that the origin of the applicability of the method stems from the nonlocality of the theoryunder consideration. PACS number(s): 11.15.Ha, 02.70.Lq, 12.20.Ds