Probing gluon saturation with next-to-leading order photon production at central rapidities in proton-nucleus collisions

Abstract

We compute the cross section for photons emitted from sea quarks in proton-nucleus collisions at collider energies. The computation is performed within the dilute-dense kinematics of the Color Glass Condensate (CGC) effective field theory. Albeit the result obtained is formally at next-to-leading order in the CGC power counting, it provides the dominant contribution for central rapidities. We observe that the inclusive photon cross section is proportional to all-twist Wilson line correlators in the nucleus. These correlators also appear in quark-pair production; unlike the latter, photon production is insensitive to hadronization uncertainties and therefore more sensitive to multi-parton correlations in the gluon saturation regime of QCD. We demonstrate that $k_{\perp }$ and collinear factorized expressions for inclusive photon production are obtained as leading twist approximations to our result. In particular, the collinearly factorized expression is directly sensitive to the nuclear gluon distribution at small $x$. Other results of interest include the realization of the Low-Burnett-Kroll soft photon theorem in the CGC framework and a comparative study of how the photon amplitude is obtained in Lorenz and light-cone gauges.

arXiv comment28 pages, 7 figures, a few points clarified, typos corrected, matches the version accepted for publication

References in corpus (34)

• Computing Quark and Gluon Distribution Functions for Very Large Nuclei
• Operator expansion for high-energy scattering
• Gluon Distribution Functions for Very Large Nuclei at Small Transverse Momentum
• Small-x F_2 Structure Function of a Nucleus Including Multiple Pomeron Exchanges
• Nonlinear Gluon Evolution in the Color Glass Condensate: I
• The Color Glass Condensate
• Green's Functions in the Color Field of a Large Nucleus
• The BFKL Equation from the Wilson Renormalization Group
• The Renormalization Group Equation for the Color Glass Condensate
• Unitarity at small Bjorken x
• Saturation Physics and Deuteron--Gold Collisions at RHIC
• Cronin Effect and High-p_T Suppression in pA Collisions
• Fock Space Distributions, Structure Functions, Higher Twists and Small x
• Non-perturbative computation of gluon mini-jet production in nuclear collisions at very high energies
• Production of gluons in the classical field model for heavy ion collisions
• High energy pA collisions in the color glass condensate approach II. Quark production
• Coherent gluon production in very high energy heavy ion collisions
• High energy pA collisions in the color glass condensate approach I. Gluon production and the Cronin effect
• Universal features of JIMWLK and BK evolution at small x
• Bremsstrahlung of a Quark Propagating through a Nucleus
• How Protons Shatter Colored Glass
• Comprehensive description of $J/\psi$ production in proton-proton collisions at collider energies
• Renormalization group evolution of multi-gluon correlators in high energy QCD
• Heavy quark pair production in high energy pA collisions: Quarkonium
• Photon production in high energy proton-nucleus collisions
• Large mass Q-Qbar production from the Color Glass Condensate
• Quarkonium production in high energy proton-nucleus collisions: CGC meets NRQCD
• Saturation and shadowing in high-energy proton-nucleus dilepton production
• Direct photon production in d+Au collisions at sqrt(s_NN)=200 GeV
• Quantitative study of the violation of kt-factorization in hadroproduction of quarks at collider energies
• Gluon propagation inside a high-energy nucleus
• Production of Forward Rapidity Photons in High Energy Heavy Ion Collisions
• Thermal photon radiation in high multiplicity p+Pb collisions at the Large Hadron Collider
• Photon from the annihilation process with CGC in the $pA$ collision

Cited by in corpus (41)

• Mining for Gluon Saturation at Colliders
• Dipole factorization for DIS at NLO: Combining the $q\bar{q}$ and $q\bar{q}g$ contributions
• nNNPDF2.0: Quark Flavor Separation in Nuclei from LHC Data
• Back-to-back inclusive dijets in DIS at small $x$: Sudakov suppression and gluon saturation at NLO
• Parametric estimate of the relative photon yields from the Glasma and the Quark-Gluon Plasma in heavy-ion collisions
• NLO impact factor for inclusive photon$+$dijet production in $e+A$ DIS at small $x$
• Quarks at next-to-eikonal accuracy in the CGC I: Forward quark-nucleus scattering
• Lam-Tung relation breaking in $Z^0$ hadroproduction as a probe of parton transverse momentum
• Pursuing the Precision Study for Color Glass Condensate in Forward Hadron Productions
• Constraining unintegrated gluon distributions from inclusive photon production in proton-proton collisions at the LHC
• TMD gluon distributions at small x in the CGC theory
• Inclusive prompt photon production in electron-nucleus scattering at small x
• $J/\psi$ polarization in the CGC+NRQCD approach
• Holographic Photon Production in Heavy Ion Collisions
• Extracting many-body correlators of saturated gluons with precision from inclusive photon+dijet final states in deeply inelastic scattering
• Photon production and elliptic flow from momentum-anisotropic quark-gluon plasma
• Isolated photon-hadron production in high energy $pp$ and $pA$ collisions at RHIC and LHC
• Inclusive prompt photon-jet correlations as a probe of gluon saturation in electron-nucleus scattering at small $x$
• Dihadron production in DIS at NLO: the real corrections
• TMD factorization for dijets + photon production from the dilute-dense CGC framework
• Prompt photon - jet angular correlations at central rapidities in p+A collisions
• Dihadron Production in DIS at Small $x$ at Next to Leading Order: Transverse Photons
• Vector quarkonia at the LHC with JETHAD: A high-energy viewpoint
• Prompt, pre-equilibrium, and thermal photons in relativistic nuclear collisions
• Prompt photon production in proton collisions as a probe of parton scattering in high energy limit
• Exotic tetraquarks at the HL-LHC with JETHAD: A high-energy viewpoint
• Study of isolated prompt photon production in $p$-Pb collisions for the ALICE kinematics
• Forward Inclusive Jet Productions in pA Collisions
• The color dipole picture for prompt photon production in $pp$ and $pPb$ collisions at the CERN-LHC
• Soft photon and two hard jets forward production in proton-nucleus collisions
• TMD parton showers for associated $\gamma$+jet production in electron-proton collisions at high energies
• General formulae for dipole Wilson line correlators with the Color Glass Condensate
• Probing nuclear modifications of parton distribution functions through the isolated prompt photon production at the LHC
• Direct Photons in Hydrodynamic Modeling of Relativistic Nuclear Collisions
• An energy independent scaling of transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton collisions
• On phenomenological study of the solution of nonlinear GLR-MQ evolution equation beyond leading order
• Triply Heavy $\Omega$ Baryons with JETHAD: A High-Energy Viewpoint
• Isolated photon production in $pp$ collisions at forward rapidities and high multiplicity events
• Tetraquark-Jet Systems at the High-Luminosity LHC
• Dijet impact factor in DIS at next-to-leading order in the Color Glass Condensate
• Exclusive photoproduction of $B_c^{\pm }$ and bottomonia pairs