Isolated photon production in proton-nucleus collisions at forward rapidity

Abstract

We calculate isolated photon production at forward rapidities in proton-nucleus collisions in the color glass condensate framework. Our calculation uses dipole cross sections solved from the running coupling Balitsky-Kovchegov equation with an initial condition fit to deep inelastic scattering data. For comparison, we also update the results for the nuclear modification factor for pion production in the same kinematics. We present predictions for future forward RHIC and LHC measurements at ffiffiffiffiffiffiffiffi s NN p ¼ 200 GeV and ffiffiffiffiffiffiffiffi s NN p ¼ 8 TeV.

Inclusive Isolated Photon in pp Collisions up to the Next Leading Order with CGC

“…Later on, recently, the photon R pA was estimated in Ref. [2] within the same framework, concluding a 30-40% reduction of R pA due to the saturation in the soft region of photon momentum ≲ a few GeV/c, which becomes more prominent for larger collision energy and/or more forward collision, as is naturally anticipated.…”

“…For the pA collision R pA conveys valuable information and it would be an intriguing question how our next leading contributions may or may not change the leading order R pA as reported in Ref. [2].…”

Forward rapidity isolated photon production in proton-nucleus collisions

“…4. Nuclear modification factor for pions at LHC energies, [1] For light hadrons the story is almost the same. Figure 4 shows the pion R pA at the same LHC kinematics as for photons in Fig.…”

“…We will first discuss the most recent one, the calculation of isolated photon production in proton-nucleus collisions in Ref. [1]. We will then compare the nuclear suppression factors to those for other prcoesses calculated in the same framework: J/ψ and single inclusive hadron production.…”

Exploring gluon saturation with photons in high energy hadron-hadron collisions

“…The leading-order (LO) contribution comes from the q → qγ channel (in the target background). The main formula for the inclusive cross section is given as [5,6,7,8] (with recent applications in [9])…”