UNC-CH Physics and Astronomy TNT Colloquium

Andrea Shindler, Michigan State University

“Flowing the Electric Dipole Moment”

The electric dipole moments (EDM) of the nucleon (neutron or proton) is a very sensitive probe of CP-violation. The current bound on the neutron EDM strongly constrains many models of beyond-the-Standard Model (BSM) physics. At the current experimental accuracy, a nonzero nucleon EDM cannot be accounted for by a phase in the quark-mass matrix. This implies that EDM is either caused by a nonzero QCD theta term or by genuine BSM physics which, at low energies, can be parametrized in terms of higher- dimensional CP-violating quark-gluon operators. I will present recent Lattice QCD results for the nucleon EDM induced by the theta term, by the quark-chromo and by the Weinberg operator. A key theoretical tool is the Gradient Flow. I will clarify the importance of the Gradient Flow in renormalizing the CP-violating operators and discuss the difficulties and pitfalls that an EDM lattice QCD calculation entails.