Exclusive quarkonium production or decay in soft gluon factorization

TL;DR

This paper applies soft gluon factorization to exclusive quarkonium production and decay, reducing nonperturbative parameters and improving predictive accuracy, demonstrated through $ ext{eta}_c+ ext{gamma}$ production at B-factories.

Contribution

The paper introduces the application of soft gluon factorization to exclusive quarkonium processes, significantly reducing nonperturbative parameters compared to traditional methods.

Findings

SGF reduces nonperturbative parameters in quarkonium calculations.

SGF improves agreement with experimental data for $ ext{eta}_c+ ext{gamma}$ production.

Closest theoretical match to data among existing models.

Abstract

In this paper, we study the application of the recently proposed soft gluon factorization (SGF) to exclusive quarkonium production or decay. We find that in the nonrelativistic QCD factorization framework there are too many nonperturbative parameters. Thanks to the factorization of kinematical physics from dynamical physics, the SGF significantly reduces the number of nonperturbative parameters. Therefore, the SGF can improve our predictive power of exclusive quarkonium production or decay. By applying to $\eta_c+\gamma$ production at B-factories, our result is the closest one to data among all theoretical calculations.