Chiral perturbation theory and numerical studies of Yukawa models

We compare simulations of a Yukawa model with a U(1) x U(1) symmetry to universal behavior predicted by chiral perturbation theory. At fixed volume, we find good agreement between measurements of the magnetization and predictions. We find it necessary to include O(L-4) terms in our fits to volume dependence in the moderately broken regime. We also present techniques to measure magnetizations numerically when the symmetry breaking term is very small and to analytically connect measurements with a small symmetry breaking term to measurements in the symmetric model. (orig.)