Hadronic decays from the lattice

TL;DR

This paper presents lattice QCD strategies to determine hadronic decay couplings, demonstrating their application to rho meson decay and finding results consistent with experimental data, including decay amplitudes and mass shifts.

Contribution

It introduces methods to extract hadronic decay couplings from lattice simulations and applies them to rho meson decay with consistent results.

Findings

Decay coupling strength agrees with experiment

Consistent decay amplitude results for different pion momenta

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

Abstract

We discuss strategies to determine hadronic decay couplings from lattice studies. As an application, we explore the decay of a vector meson to two pseudoscalar mesons 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.