Leptonic Decays of Charged Pseudoscalar Mesons - 2013

TL;DR

This paper reviews the experimental and theoretical understanding of leptonic decays of charged pseudoscalar mesons, highlighting their importance in testing the Standard Model and decay constants.

Contribution

It provides a comprehensive review of leptonic decay measurements and their implications for testing theoretical predictions of decay constants across different mesons.

Findings

Precise measurements of decay rates for various mesons.

Comparison between experimental data and theoretical decay constant predictions.

Validation of theoretical models through charm sector decay constants.

Abstract

We review the physics of purely leptonic decays of $\pi^\pm$, $K^\pm$, $D^{\pm}$, $D_s^\pm$, and $B^\pm$ pseudoscalar mesons. The measured decay rates are related to the product of the relevant weak-interaction-based CKM matrix element of the constituent quarks and a strong interaction parameter related to the overlap of the quark and antiquark wave-functions in the meson, called the decay constant $f_P$. The interplay between theory and experiment is different for each particle. Theoretical predictions of $f_B$ that are needed in the $B$ sector can be tested by measuring $f_{D^+}$ and $f_{D_s^+}$ in the charm sector. The lighter $\pi^{\pm}$ and $K^{\pm}$ mesons provide stringent comparisons between experiment and theory due to the accuracy of both the measurements and the theoretical predictions. An abridged version of this review was prepared for the Particle Data Group's 2014 edition \cite{Previous}.