The pion form factor from lattice QCD with two dynamical flavours

TL;DR

This paper presents a lattice QCD calculation of the pion's electromagnetic form factor across various parameters, successfully extrapolating to the physical point and matching experimental charge radius measurements.

Contribution

It introduces a comprehensive lattice QCD approach with multiple parameters to accurately determine the pion form factor and charge radius.

Findings

Charge radius squared: 0.441(20) fm^2

Good agreement with experimental data

Validated finite size effect checks

Abstract

We compute the electromagnetic form factor of the pion using non-perturbatively O(a) improved Wilson fermions. The calculations are done for a wide range of pion masses and lattice spacings. We check for finite size effects by repeating some of the measurements on smaller lattices. The large number of lattice parameters we use allows us to extrapolate to the physical point. For the square of the charge radius we find <r^2>=0.441(20) fm^2, in good agreement with experiment.