Hadronic transitions from the lattice

TL;DR

This paper discusses lattice methods to determine hadronic decay couplings, demonstrating their application through vector meson decay and hybrid meson decay, with results consistent with experimental data.

Contribution

It introduces lattice-based strategies for calculating hadronic decay couplings and applies them to vector and hybrid meson decays, including mass shift analysis.

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

I discuss strategies to determine hadronic decay couplings from lattice studies. As a check of the methods, I 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, I show how the transition rate can be evaluated from the amplitude for $\rho \to \pi \pi$ and from the annihilation component of $\pi \pi \to \pi \pi$. I explore the decay amplitude for two different pion momenta and find consistent results. The coupling strength found is in agreement with experiment. I also find evidence for a shift in the $\rho$ mass caused by mixing with two pion states. I also present results for the decay of a hybrid meson, for the case of heavy valence quarks.