The Mass Effect in Quarkonium Decay

TL;DR

This paper investigates the impact of mass differences in quarkonium decay within the NRQCD framework, showing that relativistic corrections significantly enhance decay width estimates.

Contribution

It introduces a method to quantify the mass difference effect using NRQCD matrix elements and separates this effect across different decay processes.

Findings

Relativistic corrections increase decay width estimates.

Mass difference effects can be systematically quantified.

Enhancement of decay widths due to relativistic effects.

Abstract

In the NRQCD factorization for productions and decays of a quakonium the difference between the quarkonium mass and the twice of the heavy quark mass is neglected at the leading order of the small velocity expansion. The effect of this difference is included in the relativistic correction. We attempt to define the difference in terms of NRQCD matrix elements and to separate the effect of the difference in several decays. It turns out that the total relativistic correcttion can be estimated by the difference. Numerically the correction will enhance the decay widths considered here.