$ρ$ and $K^*$ resonances on the lattice at nearly physical quark masses

Gunnar S. Bali, Sara Collins, Antonio Cox, Gordon Donald, Meinulf Göckeler, C. B. Lang, Andreas Schäfer

Published 2015-12-29Version 1

Working with a pion mass $m_\pi \approx 150$ MeV, we study $\pi\pi$ and $K\pi$ scattering using two flavours of non-perturbatively improved Wilson fermions at a lattice spacing $a\approx 0.071$ fm. Employing two lattice volumes with linear spatial extents of $N_s=48$ and $N_s=64$ points and moving frames, we extract the phase shifts for p-wave $\pi\pi$ and $K\pi$ scattering near the $\rho$ and $K^*$ resonances.Comparing our results to those of previous lattice studies, that used pion masses ranging from about 200 MeV up to 470 MeV, we find that the coupling $g_{\rho\pi\pi}$ appears to be remarkably constant as a function of $m_{\pi}$.