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

The charge form factor of the pion is calculated in lattice QCD. The nonperturbatively improved Sheikholeslami-Wohlert action is used together with the O(a) improved vector current. Other choices for the current are examined. The form factor is extracted for pion masses from 970 down to 360 MeV and for momentum transfers Q(2)less than or equal to2 GeV2. The mean square charge radius is extracted and compared to previous determinations, and its extrapolation to lower masses discussed.