Strong-Isospin Violation in the Neutron-Proton Mass Difference from Fully-Dynamical Lattice QCD and PQQCD
We determine the strong-isospin violating component of the neutron-proton mass difference from fully-dynamical lattice QCD and partially-quenched QCD calculations of the nucleon mass, constrained by partially-quenched chiral perturbation theory at one-loop level. The lattice calculations were performed with domain-wall valence quarks on MILC lattices with rooted staggered sea-quarks at a lattice spacing of b = 0.125 fm, lattice spatial size of L = 2.5 fm and pion masses ranging from m{sub {pi}} {approx} 290 MeV to {approx} 350 MeV. At the physical value of the pion mass, we predict M{sub n}-M{sub p}|{sup d-u} = 2.26 {+-} 0.57 {+-} 0.42 {+-} 0.10 MeV where the first error is statistical, the second error is due to the uncertainty in the ratio of light-quark masses, {eta} = m{sub u}/m{sub d}, determined by MILC, and the third error is an estimate of the systematic due to chiral extrapolation.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE - Office of Energy Research (ER)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 882225
- Report Number(s):
- JLAB-THY-06-494; DOE/ER/40150-3861; TRN: US0602956
- Journal Information:
- Nuclear Physics B, Vol. 768
- Country of Publication:
- United States
- Language:
- English
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