Probing Gluonic Spin-Orbit Correlations in Photon Pair Production

TL;DR

This paper investigates gluonic spin-orbit correlations in photon pair production during hadronic collisions, highlighting the potential to explore gluon transverse momentum distributions through angular dependencies and polarization effects.

Contribution

It introduces the application of gluonic Boer-Mulders and Sivers functions to photon pair production, providing a novel method to probe gluon TMDs in high-energy collisions.

Findings

Azimuthal angular dependencies from gluonic Boer-Mulders function.

Sensitivity of single-transverse polarized cross section to gluon Sivers function.

Numerical estimates suggest feasibility at RHIC.

Abstract

We consider photon pair production in hadronic collisions at large mass and small transverse momentum of the pair, assuming that factorization in terms of transverse momentum dependent parton distributions applies. The unpolarized cross section is found to have azimuthal angular dependencies that are generated by a gluonic version of the Boer-Mulders function. In addition, the single-transversely polarized cross section is sensitive to the gluon Sivers function. We present simple numerical estimates for the Boer-Mulders and Sivers effects in diphoton production at RHIC and find that the process would offer unique opportunities for exploring transverse momentum dependent gluon distributions.