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

TL;DR

This paper computes nucleon form factors and GPD moments using twisted mass fermions, analyzing multiple ensembles to understand nucleon structure and spin content with non-perturbative renormalization.

Contribution

It provides new lattice QCD results for nucleon form factors and GPD moments using $N_f=2+1+1$ twisted mass fermions at different pion masses and lattice spacings, with non-perturbative renormalization.

Findings

Results are consistent with other discretization schemes.

Provides nucleon spin content insights.

Quantifies form factors at physical pion masses.

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 210 MeV and 354 MeV at two values of the lattice spacing. The lattice scale is determined using the nucleon mass computed on a total of 18 N_f=2+1+1 ensembles generated at three values of the lattice spacing, $a$. The renormalization constants are evaluated non-perturbatively with a perturbative subtraction of ${\cal O}(a^2)$-terms. The moments of the generalized parton distributions are given in the $\bar{\rm MS}$ scheme at a scale of $ \mu=2$ GeV. We compare with recent results obtained using different discretization schemes. The implications on the spin content of the nucleon are also discussed.