### Particle, Astrophysics, And Nuclear Physics Seminar

Monday, November 15, 2021
2:00pm – 3:00pm

Storrs Campus
GS-119

Dr. Chien Yeah Seng, the University of Bonn

Radiative corrections in Kaon semileptonic decays and the Cabibbo angle anomaly

In recent years we observe a series of mutually inconsistent determinations of the Cabibbo angle which is responsible for the mixing between the up and down quark. These anomalies, that occur in various beta decay experiments, are at the level of 3 sigma and provide strong evidence of the deviation from precise Standard Model (SM) predictions. To sharpen them to a level sufficient to declare a discovery, we must improve the theory precision of all the precise SM inputs to these decay processes. In this talk I describe recent progress along this direction: A new high-precision calculation of the electroweak radiative corrections in Kaon semileptonic decays is performed. It features a chiral resummation of the large infrared-singular terms in the radiative corrections and a well-under-control strong interaction uncertainty based on the most recent lattice QCD inputs (by UConn physicists and collaborators). While being consistent with the previous state-of-the-art results obtained from chiral perturbation theory, we reduce the existing theory uncertainty from $$10^{-3}$$ to $$10^{-4}$$. Our result suggests that the SM electroweak effects cannot account for the anomaly in the Vus sector.

Contact:

Prof. Luchang Jin

Physics Department (primary), College of Liberal Arts and Sciences, UConn Master Calendar