Sum rules regarding the sign problem in Monte Carlo shell model calculations

The Monte Carlo shell model is a powerful technique for computational nuclear structure. Only a certain class of nuclear interactions, however, such as pairing and quadrupole, is free of the numerical noise known as the sign problem. This paper presents sum rules that relate the sign problem to the J=0 pairing matrix elements, thus illuminating the extrapolation procedure routinely used for realistic shell-model interactions. (c) 2000 The American Physical Society.