Speaker: Björn Garbrecht
Title: Problems for strong CP
Abstract: I will review the chain of arguments resulting in the belief that the theta-term (a.k.a. topological term) for the strong interactions leads to CP-violating observables such as an electric dipole moment of the neutron. Then, I will challenge this at the point where the effective quark interaction saturating the anomalous current conservation is derived from instanton calculus. By taking the infinite spacetime-volume limit before summing over topological sectors (because integer topological sectors are only forced in infinite volume), this interaction aligns with the quark masses, leaving the theta term immaterial so that there is no CP violation in the strong interactions.