Regulated chiral gauge theory and the strong CP problem

by David Kaplan

Tuesday 16 Jun 2026, 16:00 → 18:00 Europe/Zurich

4/2-037 - TH meeting room (CERN)

Extra dimensions provide a natural way to define and regulate chiral gauge theories.  In scenarios where we live on the four-dimensional boundary of a five dimensional world, anomalies are related to current flow into the extra dimension.  A consequence is that our concept of universality might need to be altered.  In particular, QCD as a stand-alone theory need not be in the same universality class as QCD embedded in the Standard Model. I discuss how lattice chiral gauge theories can be regulated in five dimensions, and show that a possible consequence is that the strong CP problem can be resolved without an axion — due to the appearance of fermion zero modes localized far from our world in the fifth dimension.

26_06_16_CERN.pdf