# New factorization theory for heavy quarkonium production and decay

## TL;DR

This paper introduces a new soft gluon factorization (SGF) approach based on QCD to improve the theoretical description of heavy quarkonium production and decay, addressing limitations of the traditional NRQCD method.

## Contribution

The paper proposes a rigorously defined SGF approach that offers better convergence than NRQCD and enhances understanding of quarkonium production and decay mechanisms.

## Key findings

- SGF has better convergence than NRQCD.
- SGF simplifies to NRQCD in phenomenological applications.
- Provides new insights into quarkonium production mechanisms.

## Abstract

The widely used nonrelativistic QCD (NRQCD) factorization theory now encounters some notable difficulties in describing quarkonium production. This may be due to the inadequate treatment of soft hadrons emitted in the hadronization process, which causes bad convergence of velocity expansion in NRQCD. In this paper, starting from QCD we propose a rigorously defined factorization approach, soft gluon factorization (SGF), to better deal with the effects of soft hadrons. After a careful velocity expansion, the SGF can be as simple as the NRQCD factorization in phenomenological studies, but has a much better convergence. The SGF may provide a new insight to understand the mechanisms of quarkonium production and decay.