NLO impact factor for inclusive photon + dijet production in e + A DIS at small x

We compute the next-to-leading order (NLO) impact factor for inclusive photon+dijet production in electron-nucleus (e+A) deeply inelastic scattering (DIS) at small x. An important ingredient in our computation is the simple structure of "shock wave" fermion and gluon propagators. This allo...

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Bibliographic Details
Published in:Physical review. D 2020-02, Vol.101 (3), Article 034028
Main Authors: Roy, Kaushik, Venugopalan, Raju
Format: Article
Language:English
Subjects:
Computation
Correlators
Cross-sections
Effective field theory
Electron-ion collisions
Evolution
Fermions
Feynman diagrams
Field theory
First principles
Gluons
Impact factors
Inelastic scattering
NUCLEAR PHYSICS AND RADIATION PHYSICS
Photons
Quantum chromodynamics
Quark & gluon jets
Renormalization group
Shock waves
Strong interaction
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Summary:We compute the next-to-leading order (NLO) impact factor for inclusive photon+dijet production in electron-nucleus (e+A) deeply inelastic scattering (DIS) at small x. An important ingredient in our computation is the simple structure of "shock wave" fermion and gluon propagators. This allows one to employ standard momentum space Feynman diagram techniques for higher order computations in the Regge limit of fixed Q2≫ΛQCD2 and x→0. Our computations in the color glass condensate (CGC) effective field theory include the resummation of all-twist power corrections Qs2/Q2, where Qs is the saturation scale in the nucleus. We discuss the structure of ultraviolet, collinear and soft divergences in the CGC, and extract the leading logs in x; the structure of the corresponding rapidity divergences gives a nontrivial first principles derivation of the JIMWLK renormalization group evolution equation for multiparton lightlike Wilson line correlators. Explicit expressions are given for the x-independent O(αs) contributions that constitute the NLO impact factor. These results, combined with extant results on NLO JIMWLK evolution, provide the ingredients to compute the inclusive photon + dijet cross section at small x to O(αs3ln(x)). First results for the NLO impact factor in inclusive dijet production are recovered in the soft photon limit. A byproduct of our computation is the LO photon+3 jet (quark-antiquark-gluon) cross section.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.101.034028