Resonance parameters of the rho-meson from asymmetrical lattices

TL;DR

This paper performs a lattice QCD calculation to determine the resonance parameters of the rho meson decay using asymmetrical lattices, providing detailed phase shift analysis at a pion mass of 304 MeV.

Contribution

It introduces a novel approach using asymmetrical lattices to extract rho meson decay parameters from lattice QCD simulations.

Findings

Resonance mass m_rho=827 MeV with uncertainties

Coupling constant g_rho-pi-pi=6.67 with uncertainty

Phase shifts evenly distributed across decay spectral region

Abstract

We present a lattice QCD calculation of the parameters of the $\rho$ meson decay. The study is carried out on spatially asymmetric boxes using nHYP-smeared clover fermions with two mass-degenerate quark flavors. Our calculations are carried out at a pion mass $m_\pi=304(2)$ MeV on the set of lattices $V=24^2\times \eta 24\times48$ with $\eta=1.0,1.25$, and 2.0 with lattice spacing $a=0.1255(7)$ fm. The resonance mass $m_\rho=827(3)(5)$ MeV and coupling constant $g_{\rho\pi\pi}=6.67(42)$ are calculate using the P-wave scattering phase shifts. We construct a 2$\times$2 correlation matrix to extract the energy of the scattering states and compute the phase shifts using the finite volume formula. By varying the degree of asymmetry, we are able to compute a set of phase shifts that are evenly distributed throughout the spectral region where the $\rho$ decays.