Hadronic decay of a vector meson from the lattice

We explore the decay of a vector meson to two pseudoscalar mesons on the lattice with Nf=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 ρ→ππ and from the annihilation component of ππ→ππ. 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 ρ mass caused by mixing with two-pion states.