HEP Colloquia 2023

by Mikhail Gorshteyn

Monday 26 Feb 2024, 15:00 → 16:30 Europe/Rome

Sala Consiliare (Department of Physics)

Cabibbo angle anomaly: status and outlook

 

Unitarity of the Cabibbo-Kobayashi-Maskawa quark mixing matrix is a mathematical expression of universality of the weak interaction across lepton and quark sectors, as well as the Standard Models completeness. The most precisely measured top-row elements warrant Standard Model tests at the 0.01% level. At this precision, the contribution of V_ub is negligible, leaving one with the simple Cabibbo unitarity pattern, |V_ud| = cosθ_c , |V_us| = sinθ_c. Combining kaon decays with nuclear beta decays, currently a 2:5? deficit is observed. This deficit, also coined the Cabibbo angle anomaly, relies on a body of high-precision experimental measurements and theoretical calculations. I give an overview of the recent developments in the SM theory of beta decays of free and bound neutrons, and kaons. I discuss future steps, as well as possible implications for BSM searches at low energies.