Probing the Weizs\"acker-Williams gluon Wigner distribution in pp collisions

TL;DR

This paper proposes a method to access the Weizs"acker-Williams gluon Wigner distribution in protons through diffractive double quarkonia production in proton collisions, combining hybrid factorization and NRQCD.

Contribution

It introduces a novel approach to probe the gluon Wigner distribution using diffractive quarkonia production and derives a concise formula for double $_{J=1}$ production.

Findings

Access to gluon Wigner distribution via quarkonia production

Derivation of a concise formula for double $_{J=1}$ production

Application of hybrid factorization and NRQCD frameworks

Abstract

We show that the diffractive forward production of two quarkonia, especially the $\chi_{cJ}$ and $\eta_c$ states, in proton-proton or proton-ion collisions can access the Weizs\"acker-Williams gluon Wigner distribution of the proton. We use the hybrid factorization approach where the collinear, double gluon PDF is applied for one of the protons and the $k_T$-dependent (Wigner or GTMD) distribution for the other. The production of quarkonia is treated in the NRQCD framework. A particularly concise formula is obtained for double $\chi_{J=1}$ production.