Justin Kaidi (University of Washington)

"Selection Rules Revisited"

Abstract: Selection rules are one of the most basic manifestations of symmetry in a quantum mechanical system. Standard selection rules are useful for proving the vanishing of certain scattering amplitudes to all orders in perturbation theory. However, there are also examples of scattering amplitudes that vanish at low orders in perturbation theory, but are non-zero at higher orders. In this talk I will introduce a generalized notion of selection rules that can account for such phenomenon. These selection rules do not have an underlying symmetry explanation in field theory, but they do have one in string theory.