Heavy Quark Fluorescence

TL;DR

This paper explains heavy quark meson decay patterns using molecular physics principles, revealing insights into the quantum wavefunction structure and composition of the Upsilon(5S) state.

Contribution

It applies the Franck-Condon principle to heavy quark decays, providing a novel interpretation of experimental data and insights into the meson's wavefunction and quark composition.

Findings

Explains decay rate patterns using molecular physics analogy.

Identifies the first Sturm-Liouville zero in the wavefunction.

Provides evidence for a largely b-anti b composition of Upsilon(5S).

Abstract

Heavy hadrons containing heavy quarks (for example, Upsilon-mesons) feature a scale separation between the heavy quark mass (about 4.5 GeV for the b-quark) and the QCD scale (about 0.3 GeV}) that controls effective masses of lighter constituents. Therefore, as in ordinary molecules, the de-excitation of the lighter, faster degrees of freedom leaves the velocity distribution of the heavy quarks unchanged, populating the available decay channels in qualitatively predictable ways. Automatically an application of the Franck-Condon principle of molecular physics explains several puzzling results of Upsilon(5S) decays as measured by the Belle collaboration, such as the high rate of Bs*-anti Bs* versus Bs*-anti Bs production, the strength of three-body B-anti B + pion decays, or the dip in B momentum shown in these decays. We argue that the data is showing the first Sturm-Liouville zero of the Upsilon(5S) quantum mechanical squared wavefunction, and providing evidence for a largely b-anti b composition of this meson.