Semileptonic decays in the limit of a heavy daughter quark

TL;DR

This paper presents a high-precision calculation of the semileptonic decay rate of b to c quarks, using a novel expansion method around the equal-mass limit, confirming previous results and providing new insights.

Contribution

It introduces a new expansion technique for calculating decay rates near the equal-mass limit of b and c quarks, achieving order alpha_s^2 accuracy.

Findings

Confirmed recent results in the limit of a lighter c-quark

Developed a new expansion method for decay rate calculations

Achieved high-precision results at order alpha_s^2

Abstract

The rate of the semileptonic decay b to c l v is calculated with order alphas^2 accuracy, as an expansion around the limit of equal masses of the b and c quarks. Recent results obtained around the limit of the c-quark much lighter than b are confirmed. Details of the new expansion method are described.