Prompt photon-jet angular correlations at central rapidities in p + A collisions

Authors

Sanjin Benić, University of Zagreb
Adrian Dumitru, CUNY Bernard M Baruch CollegeFollow

Document Type

Article

Publication Date

2018

Abstract

Photon-jet azimuthal correlations in proton-nucleus collisions are a promising tool for gaining information on the gluon distribution of the nucleus in the regime of nonlinear color fields. We compute such correlations from the process $g → q\bar{q}γ$ in the rapidity regime where both the projectile and target light-cone momentum fractions are small. By integrating over the phase space of the quark which emits the photon, subject to the restriction that the photon picks up most of the transverse momentum (to pass an isolation cut), we effectively obtain a g + A → qγ process. For nearly back-to-back photon-jet configurations we find that it dominates over the leading-order process q + A → qγ by two less powers of Q_⊥= Q_S, where Q_⊥ and Q_S denote the net photon-jet pair momentum and the saturation scale of the nucleus, respectively. We determine the transverse-momentum-dependent gluon distributions involved in g + A → qγ and the scale where they are evaluated. Finally, we provide analytic expressions for ⟨cos nφ⟩ moments, where φ is the angle between Q_⊥ and the average photon-jet transverse momentum $\tilde{P}_⊥$ and first qualitative estimates of their transverse momentum dependence.

Comments

This article was originally published in Physical Review D, available at https://doi.org/10.1103/PhysRevD.97.014012

This work is distributed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).