Speaker
Description
We determine the physical pole position of the $\rho$ resonance in $\pi\pi$ scattering using four gauge-field ensembles with 2+1 dynamical quark flavors implemented with a clover improved Wilson action. The ensembles have pion masses $m_\pi = 317,\ 296,\ 174,\ 291$ MeV and lattice spacings $a = 0.114,\ 0.090,\ 0.088,\ 0.068$ fm. For each ensemble, we obtain the $\pi\pi$ energy spectra for multiple total momenta and irreps using the GEVP. We then perform a global fit of the spectra from all ensembles to obtain the scattering amplitude and resonance parameters in the physical limit. This involves parametrizing the quark-mass dependence of the K matrix, solving the finite-volume quantization conditions, and modeling discretization effects in the energy levels. Our analysis will also enable extrapolations of semileptonic transition form factors to the physical point.