The Soft Gluon Emission Process in the Color-Octet Model for Heavy Quarkonium Production

TL;DR

This paper investigates the soft gluon emission process within the Color-Octet Model for heavy quarkonium production, highlighting the dominance of M1 transitions and their implications for polarization and universality issues.

Contribution

It introduces a potential model approach to analyze soft gluon emissions, revealing the dominance of M1 transitions over E1 transitions in quarkonium production.

Findings

M1 transition dominates over E1 transition in the process.

The dominance of M1 may explain isotropic polarization.

Results support the universality of color-octet matrix elements.

Abstract

The Color-Octet Model has been used successfully to analyze many problems in heavy quarkonium production. We examine some of the conceptual and practical problems of the soft gluon emission process in the Color-Octet Model. We use a potential model to describe the initial and final states in the soft gluon emission process, as the emission occurs at a late stage after the production of the heavy quark pair. It is found in this model that the soft gluon M1 transition, 1S0(8)->3S1(1), dominates over the E1 transition, 3PJ(8)->3S1(1), for J/psi and psi' production. Such a dominance may help resolve the questions of isotropic polarization and color-octet matrix element universality in the Color-Octet Model.