The nucleon axial charge is calculated as a function of the pion mass in full QCD. Using domain wall valence quarks and improved staggered sea quarks, we present the first calculation with pion masses as light as 354 MeV and volumes as large as (3.5 fm)3.
View Article and Find Full Text PDFThe magnetic dipole (M1), the electric quadrupole (E2), and the Coulomb quadrupole (C2) amplitudes for gammaN-->Delta are calculated in quenched lattice QCD. Using a new method, which combines an optimal choice of interpolating fields for the Delta and an overconstrained analysis, we obtain statistically accurate results for the dipole form factor and for the ratios R(EM)=E2/M1 and R(SM)=C2/M1, up to momentum transfer squared 1.5 GeV2.
View Article and Find Full Text PDFThis work presents the first calculation in lattice QCD of three moments of spin-averaged and spin-polarized generalized parton distributions in the proton. It is shown that the slope of the associated generalized form factors decreases significantly as the moment increases, indicating that the transverse size of the light-cone quark distribution decreases as the momentum fraction of the struck parton increases.
View Article and Find Full Text PDFWe perform a quenched lattice calculation of the first moment of twist-two generalized parton distribution functions of the proton, and assess the total quark (spin and orbital angular momentum) contribution to the spin of the proton.
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