D Pi scattering and D meson resonances from lattice QCD

The masses and widths of the broad scalar D_0^*(2400) and the axial D_1(2430) charmed-light resonances are extracted by simulating the corresponding D Pi and D* Pi scattering on the lattice. The resonance parameters are obtained using a Breit-Wigner fit of the elastic phase shifts. The resulting D_0^*(2400) mass is 351+/-21 MeV above the spin-average 1/4(m_D+3m_{D*}), in agreement with the experimental value of 347+/-29 MeV above. The resulting D_0^* to D Pi coupling g^{lat}=2.55+/-0.21 GeV is close to the experimental value g^{exp}<=1.92+/-0.14 GeV, where g parametrizes the width $\Gamma\equiv g^2p^*/s$. The resonance parameters for the broad D_1(2430) are also found close to the experimental values; these are obtained by appealing to the heavy quark limit, where the neighboring resonance D_1(2420) is narrow. The calculated I=1/2 scattering lengths are a_0=0.81+/-0.14 fm for D Pi and a_0=0.81+/-0.17 fm for D* Pi scattering. The simulation of the scattering in these channels incorporates quark-antiquark as well as multi-hadron interpolators, and the distillation method is used for contractions. In addition, the ground and several excited charm-light and charmonium states with various J^P are calculated using standard quark-antiquark interpolators. Our simulations are done in lattice QCD with two-dynamical light quarks at a mass corresponding to m_\pi\approx 266 MeV.