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

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.

12 pages REVTeX, 15 figures. Designation of currents clarified. Details concerning extraction of parameters added. Version accepted by Phys. Rev. D