2023/05/04 by J. Yoo, Yoo, Jun-Sik, Tanmoy Bhattacharya +7
Physics and Astronomy · #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Atomic and Subatomic Physics Research
paper · pdf · doi:10.48550/arxiv.2305.03198
One of the sensitive probes of physics beyond the standard model is the test of the unitarity of the Cabbibo-Kobyashi-Maskawa (CKM) matrix. Current analysis of the first row is based on |Vud| from fourteen superallowed 0+ → 0+ nuclear β decays and |Vud| from the kaon semileptonic decay, K → πℓ ν_ℓ. Modeling the nuclear effects in the 0+ → 0+ decays is a major source of uncertainty, which would be absent in neutron decays. To make neutron decay competitive requires improving the measurement of neutron lifetime and the axial charge, as well as the calculation of the radiative corrections (RC) to the decay. The largest uncertainty in these RCs, which comes from the non-perturbative part of the γW-box diagram and its evaluation using lattice QCD, is still not under control. Here, we show that the analogous calculations for the pion and kaon decays are robust and give \squareγWVA|π = 2.810 (26) × 10-3 and \squareγWVA|K0, S U(3) = 2.389 (17) × 10-3 in agreement with the previous analysis carried out by Feng et al. using a different discretization of the fermion action.