Pion structure from improved lattice QCD: form factor and charge radius at low masses

TL;DR

This paper presents lattice QCD calculations of the pion's charge form factor and charge radius at low pion masses, using improved actions and currents to enhance accuracy and compare with previous results.

Contribution

It introduces an improved lattice QCD approach with non-perturbative actions and currents to accurately compute pion form factors at low masses.

Findings

Charge form factor computed for pion masses 970 MeV to 360 MeV.

Mean square charge radius extracted and compared to previous results.

Form factor results extend to low momentum transfers $Q^2 \\leq 2 \,GeV^2$.

Abstract

The charge form factor of the pion is calculated in lattice QCD. The non-perturbatively improved Sheikholeslami-Wohlert action is used together with the $\mathcal{O}(a)$ improved vector current. Other choices for the current are examined. The form factor is extracted for pion masses from 970 MeV down to 360 MeV and for momentum transfers $Q^2 \leq 2 \mathrm{GeV}^2$. The mean square charge radius is extracted, compared to previous determinations and its extrapolation to lower masses discussed.