Calculation of $\rho$ meson decay width from the PACS-CS configurations

We present preliminary results on the $\rho$ meson decay width from $N_f=2+1$ full QCD configurations generated by PACS-CS Collaboration. The decay width is estimated from the $P$-wave scattering phase shift for the isospin $I=1$ two-pion system. The finite size formula presented by L"uscher in the center of mass frame and its extension to non-zero total momentum frame by Rummukainen and Gottlieb are employed for the calculations of the phase shift. Our calculations are carried out at $m_{\pi }=410\mathrm{M}\mathrm{e}\mathrm{V}$ ($m_{\pi }\mathrm{/}{m}_{\rho }=0.46$) and $a=0.091\mathrm{f}\mathrm{m}$ on a ${32}^3\times 64$ ($La=2.9\mathrm{f}\mathrm{m}$) lattice.