$\rho$ and $K^*$ resonances on the lattice at nearly physical quark masses and $N_f=2$

TL;DR

This study uses lattice QCD simulations with nearly physical quark masses to analyze $ ho$ and $K^*$ resonances, providing insights into their phase shifts and coupling constants near the physical pion mass.

Contribution

The paper presents the first lattice QCD analysis of $ ho$ and $K^*$ resonances at nearly physical quark masses with two flavors, using multiple volumes and moving frames.

Findings

Coupling $g_{\rho\pi\pi}$ remains constant across different pion masses.

Phase shifts near resonances are successfully extracted from lattice data.

Results align with previous studies at higher pion masses.

Abstract

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 $m_{\pi}$.