Light quark masses with overlap fermions in quenched QCD

We present the results of a computation of the sum of the strange and average up-down quark masses with overlap fermions in the quenched approximation. Since the overlap regularization preserves chiral symmetry at finite cutoff and volume, no additive quark mass renormalization is required and the results are O(a) improved. Our simulations are performed at beta = 6.0 and volume V = 16(3) X 32, which correspond to a lattice cutoff of similar to2 GeV and to in extension of similar to1.4 fm. The logarithmically divergent renormalization constant has been computed nonperturbatively in the RI/MOM scheme. By using the K-meson mass as experimental input, we obtain (m(d)+ (m) over cap)(RI)(2 GeV) = 120(7)(21) MeV, which corresponds to m,((MS) over bar)(2 GeV) = 102(6)(18) MeV if continuum perturbation theory and chi (PT) are used. By using the Gell-Mann-Oakes-Renner relation we also obtain [<(<psi>)over cap>psi]((MS) over bar)(2 GeV)/N-f = -0.0190(11)(33) GeV3 = -[267(5)(15) MeV](3), where the errors, are statistical and systematic respectively.