Electromagnetic pion form factor near physical point in $N_f=2+1$ lattice QCD

We compute the electromagnetic form factor of the pion at the mass $m_\pi=0.145 $ GeV on the large volume of the spatial extent 8.1 fm, corresponding to $m_\pi L \approx 6$. We use $N_f = 2 + 1$ configurations generated with a non-perturbative improved Wilson quark action with the stout-smeared link and Iwasaki gauge action at $a^{-1}=2.333$ GeV. We obtain the form factor at small momentum transfer without the twisted boundary condition.Our preliminary results for the form factor and the mean-squared charge radius are reasonably consistent with the experiment.