Light quark masses from scalar sum rules

Abstract

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 scheme, we find m s (2 GeV) = 99 ± 16 MeV. Making use of this result and the lightquark 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.

QCD Sum Rules - A Working Tool for Hadronic Physics

“…An updated analysis of kaon S wave scattering on π, η, η ′ is used to reproduce the hadronic spectral density. The sum rule yields [ 15] for the running mass in the MS scheme: m s (2GeV) = 99 ± 16 MeV, in a good agreement with the recent lattice QCD estimates. Using the ratios (19) one obtains m u (2GeV) = 2.9 ± 0.6 MeV and m d (2GeV) = 5.2 ± 0.9 MeV.…”

Time-varying coupling strengths, nuclear forces and unification

“…[26]) so thus far we avoid the problem of having scaledependent quantities in a context where mass scales may be time-dependent (see section 4.1).…”

K π vector form factor constrained by τ → Kπντ and K l3 decays

“…According to the kinematical configuration, q represents the exchanged (K l 3 ) or the total (τ → Kπν τ ) Kπ four-momentum. A good knowledge of these form factors is of fundamental importance for the determination of many parameters of the Standard Model, such as the quark-mixing matrix element |V us | obtained from K l 3 decays [1], or the strange-quark mass m s determined from the scalar QCD strange spectral function [2]. Recently, several collaborations have produced data for K l 3 decays and new high-statistics data for τ → Kπν τ have been published by the B factories.…”