Constraining unintegrated gluon distributions from inclusive photon production in proton-proton collisions at the LHC
We compute the leading order (LO) qg→qγ and next-to-leading order (NLO) gg→qq¯γ contributions to inclusive photon production in proton-proton (p+p) collisions at the LHC. These channels provide the dominant contribution at LO and NLO for photon transverse momenta kγ⊥ corresponding to momentum fracti...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
[10 April 2019]
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| In: |
Physics letters
Year: 2019, Volume: 791, Pages: 11-16 |
| ISSN: | 1873-2445 |
| DOI: | 10.1016/j.physletb.2019.02.007 |
| Online Access: | Verlag, Volltext: https://doi.org/10.1016/j.physletb.2019.02.007 Verlag, Volltext: http://www.sciencedirect.com/science/article/pii/S037026931930098X 
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| Author Notes: | Sanjin Benić, Kenji Fukushima, Oscar Garcia-Montero, Raju Venugopalan |
| Summary: | We compute the leading order (LO) qg→qγ and next-to-leading order (NLO) gg→qq¯γ contributions to inclusive photon production in proton-proton (p+p) collisions at the LHC. These channels provide the dominant contribution at LO and NLO for photon transverse momenta kγ⊥ corresponding to momentum fractions of x≤0.01 in the colliding protons. Our computations, performed in the dilute-dense framework of the Color Glass Condensate effective field theory (CGC EFT), show that the NLO contribution dominates at small-x because it is sensitive to k⊥-dependent unintegrated gluon distributions in both of the protons. We predict a maximal 10% modification of the cross section at low kγ⊥ as a direct consequence of the violation of k⊥-factorization. The coherence effects responsible for this modification are enhanced in nuclei and can be identified from inclusive photon measurements in proton-nucleus collisions. We provide numerical results for the isolated inclusive photon cross section for kγ⊥≤20 GeV in p+p collisions that can be tested in the future at the LHC. |
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| Item Description: | Available online: 12 February 2019 Gesehen am 16.04.2019 |
| Physical Description: | Online Resource |
| ISSN: | 1873-2445 |
| DOI: | 10.1016/j.physletb.2019.02.007 |