title: Variance-reduced estimator of the connected two-point function in the presence of a broken Z(2)-symmetry.
abstract: The exchange or geometric cluster algorithm allows us to define a variance-reduced estimator of the connected two-point function in the presence of a broken Z(2)-symmetry. We present numerical tests for the improved Blume-Capel model on the simple-cubic lattice. We perform simulations for the critical isotherm, the low-temperature phase at vanishing external field, and, for comparison, also the high-temperature phase. For the connected two-point function, a substantial reduction of the variance can be obtained, allowing us to compute the correlation length ξ with high precision. Based on these results, estimates for various universal amplitude ratios that characterize the universality class of the three-dimensional Ising model are computed.
authors.affiliation: Institut für Physik, Humboldt-Universität zu Berlin, Newtonstrasse 15, 12489 Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hasenbusch