Effective chiral Lagrangians and lattice QCD

We propose a general method to obtain accurate estimates for some of the "l ow-energy constants" in the one-loop effective chiral Lagrangian by means o f simulating lattice QCD. In particular, the method is sensitive to those c onstants whose values are required to test the hypothesis of a massless up- quark. Initial tests performed in the quenched approximation confirm that g ood statistical precision can be achieved. As a byproduct we obtain an accu rate estimate for the ratio of pseudoscalar decay constants, F-K/F-pi, in t he quenched approximation, which lies 10% below the experimental result. Th e quantities that serve to extract the low-energy constants also allow a te st of the scaling behaviour of different discretizations of QCD and a searc h for the effects of dynamical quarks. (C) 2000 Elsevier Science B.V. All r ights reserved.