Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2021

TL;DR

This paper provides comprehensive world averages of key properties of $b$-hadron, $c$-hadron, and $ au$-lepton particles, consolidating measurements up to early 2021 to support ongoing research in heavy flavor physics.

Contribution

It presents the first extensive set of standardized averages for heavy flavor and lepton properties, incorporating recent measurements and consistent analysis methods.

Findings

Updated averages for branching fractions and lifetimes

Precise measurements of neutral meson mixing and CP violation

Refined CKM matrix element values

Abstract

This paper reports world averages of measurements of $b$-hadron, $c$-hadron, and $\tau$-lepton properties obtained by the Heavy Flavour Averaging Group using results available before April 2021. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays, and Cabibbo-Kobayashi-Maskawa matrix elements.