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

Scientific paper - Original scientific paper

• Author: Sanjin Benić; MBZ: 310875
• Author: Kenji Fukushima
• Author: Raju Venugopalan
• Author's institution: University of Zagreb; Faculty of Science
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

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⊥ 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.

• Keywords (english): Heavy Ion Phenomenology; NLO computations
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Journal of High Energy Physics
• Numbering: vol. 2017, no. 1, 115
• p-ISSN: 1126-6708
• e-ISSN: 1029-8479
• DOI: https://doi.org/10.1007/JHEP01(2017)115
• URN:NBN: urn:nbn:hr:217:265326
• Publication: 2017
• Document URL: https://link.springer.com/article/10.1007%2FJHEP01%282017%29115
• Type of resource: Text
• Access conditions: Open access
• Public note: Open Access, © The Author(s) 2017. Article funded by SCOAP3 and licensed under CC BY 4.0. Received: October 8, 2016. Accepted: January 15, 2017. Published: January 26, 2017.
• Created on: 2020-02-27 19:19:23