$D \rightarrow Kl{\nu}$ semileptonic decay using lattice QCD with HISQ at physical pion masses

TL;DR

This paper presents a lattice QCD calculation of form factors for the $D ightarrow Kl{ u}$ decay at physical pion masses, enabling a precise determination of the CKM matrix element $V_{cs}$ to test the Standard Model.

Contribution

The study provides the first lattice QCD calculation of scalar and vector form factors for $D ightarrow Kl{ u}$ decay using physical pion mass ensembles, improving CKM matrix element extraction.

Findings

Form factors computed over a large $q^2$ range including zero.

Results enable precise extraction of $V_{cs}$ from experimental data.

Supports testing of CKM unitarity and Standard Model validity.

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. We present a lattice QCD calculation of the scalar and the vector form factors (over a large $q^2$ region including $q^2 = 0$) associated with the $D \rightarrow Kl{\nu}$ semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, $V_{cs}$ in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the $N_f =2+1+1$ MILC HISQ ensembles with the physical light quark masses.