Abstract

The seminar will take place via Zoom here.

Abstract: The quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. The uncertainties in the unitarity checks of the second row and second column of the CKM matrix are dominated by that of the central CKM matrix element, |V_{cs}|. This element is calculated from the studies of the leptonic and semileptonic meson decays involving charged quark flavour changing current from charm to strange by combining the experimental decay rate with the vector form factor calculated from lattice QCD . In this talk, I would present our (HPQCD) latest high precision lattice QCD calculation (Phys.Rev.D 104, 034505) of the scalar and the vector form factors for the D meson to K meson semi-leptonic decay over the full kinetic (q^2) range of the physical decay process. This calculation allows us to precisely determine |V_{cs}| in the Standard Model, by comparing the lattice QCD result for the vector form factors and the experimental decay rate. This is the first time that |V_{cs}| has been determined with an accuracy that allows its difference from 1 to be seen.