Light quark masses from scalar sum rules

In this work, the mass of the strange quark is calculated from QCD sum rules for the divergence of the strangeness-changing vector current. The phenomenological scalar spectral function which enters the sum rule is determined from our previous work on strangeness-changing scalar form factors [1]. For the running strange mass in the (MS) over bar scheme, we find m(s) (2 GeV) = 99 +/- 16 MeV. Making use of this result and the light quark mass ratios obtained from chiral perturbation theory, we are also able to extract the masses of the lighter quarks m(u) and m(d). We then obtain m(u) (2 GeV) = 2.9 +/- 0.6 MeV and m(d) (2 GeV) = 5.2 +/- 0.9 MeV. In addition, we present an updated value for the light quark condensate.