Applications of QCD Sum Rules to Heavy Quark Physics

TL;DR

This paper reviews the application of QCD sum rules to heavy-flavour hadron decays, including decay constants, form factors, and nonlocal amplitudes, highlighting their importance in understanding heavy quark processes.

Contribution

It provides a comprehensive overview of QCD sum rules methods applied to various heavy quark decay processes, including new insights into nonfactorizable contributions.

Findings

Sum rules for decay constants of heavy-light mesons are established.

QCD light-cone sum rules effectively calculate heavy-to-light form factors.

Nonlocal hadronic amplitudes in rare B decays are analyzed using sum rules.

Abstract

In these lectures, I present several important applications of QCD sum rules to the decay processes involving heavy-flavour hadrons. The first lecture is introductory. As a study case, the sum rules for decay constants of the heavy-light mesons are considered. They are relevant for the leptonic decays of $B$-mesons. In the second lecture I describe the method of QCD light-cone sum rules used to calculate the heavy-to-light form factors at large hadronic recoil, such as the $B\to \pi \ell \nu_\ell$ form factors. In the third lecture, the nonlocal hadronic amplitudes in the flavour-changing neutral current decays $B\to K^{(*)}\ell\ell$ are discussed. Light-cone sum rules provide important nonfactorizable contributions to these amplitudes.