Electroweak box diagrams on the lattice for pion and neutron decay

Jun-Sik Yoo, Tanmoy Bhattacharya, Rajan Gupta +2

CKM matrix is unitary by construction in the standard model(SM). The recent analyses on the first row of CKM matrix show $\approx 3\sigma$ tension with unitarity. Nonperturbative calcu…