Improved determination of inclusive electromagnetic decay ratios of heavy quarkonium from QCD

TL;DR

This paper introduces a new power counting scheme in potential NRQCD that improves the accuracy of electromagnetic decay ratio predictions for heavy quarkonium, aligning theory more closely with experimental data.

Contribution

It incorporates the static potential exactly in the leading order Hamiltonian, leading to significant relativistic correction calculations and improved decay ratio predictions.

Findings

Large effect of new power counting on decay ratios

Updated $$ decay to two photons value

Better consistency with experimental charmonium decay ratios

Abstract

We consider a different power counting in potential NRQCD by incorporating the static potential exactly in the leading order Hamiltonian. We compute the leading relativistic corrections to the inclusive electromagnetic decay ratios in this new scheme. The effect of this new power counting is found to be large (even for top). We produce an updated value for the $\eta_b$ decay to two photons. This scheme also brings consistency between the weak coupling computation and the experimental value of the charmonium decay ratio.