# Nucleon generalized form factors from two-flavor lattice QCD

## TL;DR

This paper calculates nucleon generalized form factors using lattice QCD with near-physical quark masses, providing insights into nucleon structure and comparing fit strategies for extracting form factors.

## Contribution

It presents the first determination of nucleon generalized form factors at near-physical pion masses using lattice QCD and compares different fitting methods for analysis.

## Key findings

- Direct fit to matrix elements yields stable form factors.
- Results are consistent with theoretical expectations.
- Provides data for nucleon angular momentum and spin densities.

## Abstract

We determine the generalized form factors, which correspond to the second Mellin moment (i.e., the first $x$-moment) of the generalized parton distributions of the nucleon at leading twist. The results are obtained using lattice QCD with $N_f=2$ nonperturbatively improved Wilson fermions, employing a range of quark masses down to an almost physical value with a pion mass of about 150 MeV. We also present results for the isovector quark angular momentum and for the first $x$-moment of the transverse quark spin density. We compare two different fit strategies and find that directly fitting the ground state matrix elements to the functional form expected from Lorentz invariance and parametrized in terms of form factors yields comparable, and usually more stable results than the traditional approach where the form factors are determined from an overdetermined linear system based on the fitted matrix elements.