Universal amplitude ratios in the critical two-dimensional Ising model on a torus

Using results from conformal field theory, we compute several universal amp litude ratios for the two-dimensional Ising model at criticality on a symme tric torus. These include the correlation-length ratio x* = lim(L-->infinit y) xi(L)/L and the first four magnetization moment ratios V-2n = [M-2n]/[M- 2](n). As a corollary we get the first four renormalized 2n-point coupling constants for the massless theory on a symmetric torus, G(2n)*. We confirm these predictions by a high-precision Monte Carlo simulation.