EPP Theory Seminar: Steve Sharpe "Scattering observables from lattice QCD: progress in two- and three-particle channels"
Lattice QCD calculations have made great strides towards calculating
resonance properties and decay amplitudes in cases where only two-particle
channels are present. This required development of both theoretical formalism
and simulation methods. However,
many problems of interest involve three-particle channels,
e.g. the Roper resonance and K -> 3 pion decays, and for these
the theoretical formalism to relate the finite-volume lattice results to
infinite-volume scattering quantities has been lacking.
After reviewing methods and results involving two particles, I describe recent
work with Raul Briceno and Max Hansen in which we have developed the
needed formalism in an (almost) general relativistic field theory of
identical scalar particles, and discuss the steps needed to make the
formalism completely general.