High-precision determination of the light-quark masses from realistic lattice QCD
- Department of Applied Mathematics and Theoretical Physics, Cambridge University, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
- Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6 (Canada)
- Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)
- Laboratory of Elementary-Particle Physics, Cornell University, Ithaca, New York 14853 (United States)
Three-flavor lattice QCD simulations and two-loop perturbation theory are used to make the most precise determination to date of the strange-, up-, and down-quark masses, m{sub s}, m{sub u}, and m{sub d}, respectively. Perturbative matching is required in order to connect the lattice-regularized bare-quark masses to the masses as defined in the MS scheme, and this is done here for the first time at next-to-next-to leading (or two-loop) order. The bare-quark masses required as input come from simulations by the MILC collaboration using so-called staggered quarks, with three flavors of light quarks in the Dirac sea; these simulations were previously analyzed in a joint study by the HPQCD and MILC collaborations, using degenerate u and d quarks, with masses as low as m{sub s}/8, and two values of the lattice spacing, with chiral extrapolation/interpolation to the physical masses. With the new perturbation theory presented here, the resulting MS masses are m{sub s}{sup MS}(2 GeV)=87(0)(4)(4)(0) MeV, and m-circumflex{sup MS}(2 GeV)=3.2(0)(2)(2)(0) MeV, where m-circumflex=(1/2)(m{sub u}+m{sub d}) is the average of the u and d masses. The respective uncertainties are from statistics, simulation systematics, perturbation theory, and electromagnetic/isospin effects. The perturbative errors are about a factor of 2 smaller than in an earlier study using only one-loop perturbation theory. Using a recent determination of the ratio m{sub u}/m{sub d}=0.43(0)(1)(0)(8) due to the MILC collaboration, these results also imply m{sub u}{sup MS}(2 GeV)=1.9(0)(1)(1)(2) MeV and m{sub d}{sup MS}(2 GeV)=4.4(0)(2)(2)(2) MeV. A technique for estimating the next order in the perturbative expansion is also presented, which uses input from simulations at more than one lattice spacing; this method is used here in the estimate of the systematic uncertainties.
- OSTI ID:
- 20774816
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 73, Issue 11; Other Information: DOI: 10.1103/PhysRevD.73.114501; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electromagnetic mass splittings of the low lying hadrons and quark masses from 2+1 flavor lattice QCD+QED
{upsilon} spectrum and m{sub b} from full lattice QCD