ρmeson decay in2+1flavor lattice QCD

We perform a lattice QCD study of the $\ensuremath{\rho}$ meson decay from the ${N}_{f}=2+1$ full QCD configurations generated with a renormalization group improved gauge action and a nonperturbatively $O(a)$-improved Wilson fermion action. The resonance parameters, the effective $\ensuremath{\rho}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ coupling constant and the resonance mass, are estimated from the $P$-wave scattering phase shift for the isospin $I=1$ two-pion system. The finite size formulas are employed to calculate the phase shift from the energy on the lattice. Our calculations are carried out at two quark masses, ${m}_{\ensuremath{\pi}}=410\text{ }\text{ }\mathrm{MeV}$ (${m}_{\ensuremath{\pi}}/{m}_{\ensuremath{\rho}}=0.46$) and ${m}_{\ensuremath{\pi}}=300\text{ }\text{ }\mathrm{MeV}$ (${m}_{\ensuremath{\pi}}/{m}_{\ensuremath{\rho}}=0.35$), on a ${32}^{3}\ifmmode\times\else\texttimes\fi{}64$ ($La=2.9\text{ }\text{ }\mathrm{fm}$) lattice at the lattice spacing $a=0.091\text{ }\text{ }\mathrm{fm}$. We compare our results at these two quark masses with those given in the previous works using ${N}_{f}=2$ full QCD configurations and the experiment.