TEMPERING SIMULATIONS IN THE 4-DIMENSIONAL + -J ISING SPIN-GLASS IN AMAGNETIC-FIELD/

We study the four dimensional (4D) +/-J Ising spin glass in a magnetic field with the simulated tempering algorithm recently introduced by M arinari and Parisi. We compute numerically the order parameter functio n P(q) and analyze the temperature dependence of the first four cumula nts of the distribution. We discuss the evidence in favor of the exist ence of a phase transition in a field. Assuming a well defined transit ion we are able to bound its critical temperature. (C) 1998 Elsevier S cience B.V. All rights reserved.