Our results exclude the m u = 0 solution to the strong C P problem by more than 24 standard deviations. For the light quark masses we obtain, m u = 2.27 ( 6 ) ( 5 ) ( 4 ) and m d = 4.67 ( 6 ) ( 5 ) ( 4 ) MeV in the modified minimal subtraction scheme at 2 G e V and the isospin breaking ratios m u / m d = 0.485 ( 11 ) ( 8 ) ( 14 ), R = 38.2 ( 1.1 ) ( 0.8 ) ( 1.4 ), and Q = 23.4 ( 0.4 ) ( 0.3 ) ( 0.4 ). Those masses help predict what particle collisions at the LHC and. Knowing the light-quark masses is 'absolutely essential in a bunch of ways,' Mackenzie says.

That's 0.214 and 0.510 of the mass of the proton, respectively. For accepted values of the constituent up-down quark mass difference we find that. 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. The team finds that an up quark weighs 2.01 +/- 0.14 megaelectron-volts, whereas a down quark weighs 4.79 +/- 0.16 MeV. A recently proposed nonrelativistic many-body quark model is used to. 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. Using the same data we determine here the corrections to Dashen’s theorem and the individual up and down quark masses. We explore the scenario where the core of a neutron star (having experienced a transition to an up and down quark phase) shrinks into the equilibrated quark object after reaching strange quark matter saturation density (where a composition of up, down and strange quarks is the favored state of matter).

In a previous Letter we determined the isospin mass splittings of the baryon octet from a lattice calculation based on N f = 2 + 1 QCD simulations to which QED effects have been added in a partially quenched setup.

Down quark