Nucleon Form Factors from the Feynman-Hellmann Method in Lattice QCD

Abstract

Lattice QCD calculations of the nucleon electromagnetic form factors are of interest at both the high and low momentum transfer regions. For high momentum transfers especially there are open questions which require more intense study, such as the potential zero crossing in the proton’s electric form factor. We will present recent progress from the QCDSF/UKQCD/CSSM collaboration on the calculation of these form factors using the Feynman-Hellmann method in lattice QCD. The Feynman-Hellmann method allows for greater control over excited states which we take advantage of by going to high values of the momentum transfer. In this proceeding we present results of the form factors up to $6\ \textrm{GeV}^2$ , using $𝑁_f=2+1$ flavour fermions for three different pion masses in the range $310-470 \textrm{MeV}$. The results are extrapolated to the physical pion mass through the use of a flavour breaking expansion.