Nucleon form factors and moments of generalized parton distributions using Nf=2+1+1 twisted mass fermions

Abstract

We present results on the axial and the electromagnetic form factors of the nucleon, as well as on the first moments of the nucleon generalized parton distributions using maximally twisted mass fermions. We analyze two N f=2+1+1 ensembles having pion masses of 213 MeV and 373 MeV each at a different value of the lattice spacing. The lattice scale is determined using the nucleon mass computed on a total of 17 Nf=2+1+1 ensembles generated at three values of the lattice spacing, a. The renormalization constants are evaluated nonperturbatively with a perturbative subtraction of O(a2) terms. The moments of the generalized parton distributions are given in the MS̄ scheme at a scale of μ=2 GeV. We compare with recent results obtained using different discretization schemes. The implications on the spin content of the nucleon are also discussed. © 2013 American Physical Society.