Up and Down Quark Masses and Corrections to Dashen’s Theorem from Lattice QCD and Quenched QED

Fodor, Z.; Krieg, S.; Szabo, Kalman; Sastre, A.; Hoelbling, C.; Lippert, Th.; Varnhorst, L.; Portelli, A.; Lellouch, L.

doi:10.1103/PhysRevLett.117.082001

Journal Article

FZJ-2016-04440

Up and Down Quark Masses and Corrections to Dashen’s Theorem from Lattice QCD and Quenched QED

Fodor, Z. ; Hoelbling, C. ; Krieg, S.FZJ* ; Lellouch, L. ; Lippert, T.FZJ* ; Portelli, A. ; Sastre, A. ; Szabo, K.FZJ* ; Varnhorst, L.

2016
APS College Park, Md.

Physical review letters 117(8), 082001 (2016) [10.1103/PhysRevLett.117.082001]

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Please use a persistent id in citations: http://hdl.handle.net/2128/12218 doi:10.1103/PhysRevLett.117.082001

Abstract: In a previous Letter [Borsanyi et al., Phys. Rev. Lett. 111, 252001 (2013)] we determined the isospin mass splittings of the baryon octet from a lattice calculation based on Nf=2+1 QCD simulations to which QED effects have been added in a partially quenched setup. Using the same data we determine here the corrections to Dashen’s theorem and the individual up and down quark masses. Our ensembles include 5 lattice spacings down to 0.054 fm, lattice sizes up to 6 fm, and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashen’s theorem, we obtain ϵ=0.73(2)(5)(17), where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, mu=2.27(6)(5)(4) and md=4.67(6)(5)(4) MeV in the modified minimal subtraction scheme at 2 GeV and the isospin breaking ratios mu/md=0.485(11)(8)(14), R=38.2(1.1)(0.8)(1.4), and Q=23.4(0.4)(0.3)(0.4). Our results exclude the mu=0 solution to the strong CP problem by more than 24 standard deviations.

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