Determination of the up/down-quark mass within QCD sum rules in the scalar channel.

In this work, we determine up/down-quark mass m q = u / d in the isoscalar scalar channel from both the Shifman–Vainshtein–Zakharov (SVZ) and the Monte-Carlo-based QCD sum rules. The relevant spectral function, including the contributions from the f 0 (500) , f 0 (980) and f 0 (1370) resonances, is determined from a sophisticated U(3) chiral study. Via the traditional SVZ QCD sum rules, we give the prediction to the average light-quark mass m q (2 GeV) = 1 2 (m u (2 GeV) + m d (2 GeV)) = (3. 46 - 0.22 + 0.16 ± 0.33) MeV . Meanwhile, by considering the uncertainties of the input QCD parameters and the spectral functions of the isoscalar scalar channel, we obtain m q (2 GeV) = (3.44 ± 0.14 ± 0.32) MeV from the Monte-Carlo-based QCD sum rules. Both results are perfectly consistent with each other, and nicely agree with the Particle Data Group value within the uncertainties. [ABSTRACT FROM AUTHOR]