Semileptonic Charm Decays: mini review

TL;DR

This review discusses the importance of semi-leptonic charm decays in flavor physics, emphasizing their role in testing lattice QCD calculations and extracting CKM matrix elements, especially |V_{ub}|, through experimental and theoretical inputs.

Contribution

It provides an overview of recent experimental results on semi-leptonic D decays and highlights their use in validating lattice QCD form factor calculations for CKM matrix element extraction.

Findings

Latest measurements of exclusive D semi-leptonic decays summarized.

Semi-leptonic D decays used to validate lattice QCD form factors.

CKM matrix elements can be tested via D decay data.

Abstract

One important task in the field of flavor physics is to over-constrain the CKM matrix. To best extract CKM matrix elements, we need inputs from both experimental data and theoretical calculations. Latest knowledge about the CKM matrix shows our understanding about sin$2\beta$ is the best thanks to clean theory and large statistics from experiments. In contrast, our understanding of both mixing and $|V_{ub}|$ have limitations from theoretical predictions. In order to extract the value of $|V_{ub}|$ from the branching fraction measurement, we need information on the hadronic form factor $f_+(q^2)$. Our best understanding about $f_+(q^2)$ is from lattice QCD calculations. To validate improved lattice QCD calculations for the form factor in semi-leptonic B decays, we can use semi-leptonic $D$ decays as a test and calibration. Since the CKM matrix elements $|V_{cs(d)}|$ can be obtained precisely from unitarity, we have a reliable method to check the lattice QCD calculations. The experimental results of $D$ semi-leptonic decays can be summarized in two main categories: the exclusive decays and the inclusive decays. Latest measurements from the exclusive semi-leptonic $D$ decays are discussed here.