Hadronic decay of a vector meson from the lattice

TL;DR

This paper investigates the decay of a vector meson into two pseudoscalar mesons using lattice QCD with two sea quark flavors, demonstrating how to evaluate decay amplitudes and observing effects on the rho meson mass.

Contribution

It introduces a method to compute decay amplitudes from lattice QCD data and provides results consistent with experimental coupling strengths.

Findings

Decay amplitude consistent across different pion momenta

Coupling strength agrees with experimental data

Evidence of rho mass shift due to mixing with two-pion states

Abstract

We explore the decay of a vector meson to two pseudoscalar mesons on the lattice with $N_f=2$ flavours of sea quark. Although we are working with quark masses that do not allow a physical decay, we show how the transition rate can be evaluated from the amplitude for $\rho \to \pi \pi$ and from the annihilation component of $\pi \pi \to \pi \pi$. We explore the decay amplitude for two different pion momenta and find consistent results. The coupling strength we find is in agreement with experiment. We also find evidence for a shift in the $\rho$ mass caused by mixing with two pion states.