Leptonic decays of charged pseudoscalar mesons - 2012

TL;DR

This paper reviews the leptonic decay processes of various charged pseudoscalar mesons, highlighting the relationship between decay rates, CKM matrix elements, and decay constants, and discusses the interplay of experimental data and theoretical predictions.

Contribution

It provides a comprehensive review of leptonic meson decays, comparing experimental results with theoretical predictions, and emphasizes the importance of charm sector measurements for understanding B meson decay constants.

Findings

Precise measurements of decay constants for light mesons like pions and kaons.

Testing of theoretical models through charm sector decay constants.

Insights into CKM matrix elements from leptonic decay data.

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. This review was prepared for the Particle Data Group's 2012 edition.