Isolated photon-hadron production in high energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mi>A</mml:mi></mml:math> collisions at RHIC and LHC

Abstract

We compute the isolated photon production in association with a charged hadron at midrapidity in $pp$ and $pA$ based on the Color Glass Condensate (CGC) framework of high energy Quantum Chromodynamics (QCD) where, for the first time, we incorporate the Sudakov effect of soft gluon emissions. Our results are based on the leading order $qg\ensuremath{\rightarrow}q\ensuremath{\gamma}$ channel in the CGC framework and confronted with the recent data from Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) concerning the angular distributions and out-of-plane transverse momentum distributions. We find that, while the CGC computation alone results in too narrow distributions, with the help of the Sudakov effect, we can get a satisfactory description of the data. With this as a benchmark, we provide predictions for the magnitude of the nuclear effect brought by the phenomena of gluon saturation in the CGC.

Topics & Concepts