Abstract
We highlight the principal results of a computation in the Color Glass Condensate effective field theory (CGC EFT) of the next-to-leading order (NLO) impact factor for inclusive photon+dijet production at Bjorken $x_{\rm Bj} \ll 1$ in deeply inelastic electron-nucleus (e+A DIS) collisions. When combined with extant results for next-to-leading log $x_{\rm Bj}$ JIMWLK renormalization group (RG) evolution of gauge invariant two-point ("dipole") and four-point ("quadrupole") correlators of light-like Wilson lines, the inclusive photon+dijet e+A DIS cross-section can be determined to $\sim 10$\% accuracy. Our computation simultaneously provides the ingredients to compute fully inclusive DIS, inclusive photon, inclusive dijet and inclusive photon+jet channels to the same accuracy. This makes feasible quantitative extraction of many-body correlators of saturated gluons and precise determination of the saturation scale $Q_{S,A}(x_{\rm Bj})$ at a future Electron-Ion Collider. An interesting feature of our NLO result is the structure of the violation of the soft gluon theorem in the Regge limit. Another is the appearance in gluon emission of time-like non-global logs which also satisfy JIMWLK RG evolution.
Highlights
The many-body recombination and screening of gluons in the high energy or small Bjorken xBj Regge limit of QCD competes with their rapid bremsstrahlung and leads to the perturbative unitarization of cross sections
We will discuss the principal results of a first computation in the color glass condensate (CGC) effective field theory (EFT) of the next-to-leading order (NLO) “impact factor” for inclusive photon þ dijet production in deeply inelastic scattering of electrons off nuclei (e þ A DIS) at high energies
As we will outline here, knowing the NLO impact factor enables us to compute the photon þ dijet cross section in e þ A DIS to Oðα3S lnð1=xBjÞÞ corresponding to ∼10% accuracy at the energies and nuclear saturation scales accessible at an ElectronIon Collider (EIC)
Summary
We highlight the principal results of a computation [1] in the color glass condensate effective field theory of the next-to-leading order (NLO) impact factor for inclusive photon þ dijet production at Bjorken xBj ≪ 1 in deeply inelastic electron-nucleus (e þ A DIS) collisions. The many-body recombination and screening of gluons in the high energy or small Bjorken xBj Regge limit of QCD competes with their rapid bremsstrahlung and leads to the perturbative unitarization of cross sections. This gluon saturation phenomenon [2,3], in the color glass condensate (CGC) effective field theory (EFT) picture [4,5,6,7,8,9,10], occurs when the phase-space occupancy n of gluons for transverse momenta k⊥ ≤ QSðxBjÞ becomes of the order of the inverse of the QCD coupling αS. To elaborate on our discussion, it is instructive to first briefly consider our previous computation [27] in the CGC EFT of the leading order (LO) inclusive photon þ dijet (γ þ qq ) e þ A DIS cross section: 2470-0010=2020=101(7)=071505(8)
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