Defining Chiral Gauge Theories Beyond Perturbation Theory
Abstract: I discuss a recent proposal for nonperturbatively regulating the high-energy divergences of chiral gauge theories, a long-standing problem in quantum field theory, and its possible raminfication on Standard Model physics. The proposal is a well-defined field theoretic framework in which ordinary fermions have conventional gauge coupling while their mirror partners have extremely soft form factors. This can be implemented on the lattice by coupling five-dimensional domain wall fermions to four-dimensional gauge fields that are extended into the extra dimension via gradient flow. In the limit of an infinite extra dimension, the effective fermion operator for this construction has the expected chiral properties, namely that it obeys the Ginsparg-Wilson equation. After explaining the details of this construction, I discuss open questions about the proposal, including questions about residual coupling between the mirror and ordinary fermions via topological effects and how this might affect our understanding of Standard Model physics.
1:30pm-2:30pm calendar page