Paper detail

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=16^3X32, which correspond to a lattice cutoff of ~2 GeV and to an extension of ~1.4 fm. The logarithmically divergent renormalization constant has been computed non-perturbatively in the RI/MOM scheme. By using the K-meson mass as experimental input, we obtain (m_s + m_l)^RI(2 GeV) = 120(7)(21) MeV, which corresponds m_s^MS (2 GeV) = 102(6)(18) MeV if continuum perturbation theory and ChiPT are used. By using the GMOR relation we also obtain <psi psi>^MS(2 GeV)/N_f = - 0.0190(11)(33) GeV^3 = - [267(5)(15) MeV]^3.