Quasielastic response with a real-time path-integral Monte Carlo method

We formulate the quasielastic response of a nonrelativistic many-body system at zero temperature in terms of ground-state density-matrix elements and real-time path integrals that embody the final-state interactions. While the former provide the weight for a conventional Monte Carlo calculation, the latter require a more sophisticated treatment. We argue that the stationary-phase Monte Carlo technique recently developed by Doll et al. can be used to study the approach to "Y scaling." We perform calculations for a particle in a potential well in one and three dimensions and compare them with the exact results available for these models.