Back-to-back inclusive dijets in DIS at small x: Sudakov suppression and gluon saturation at NLO

Abstract

Back-to-back dijet cross-sections in deeply inelastic scattering (DIS) at small xBj are suppressed by many-body multiple scattering and screening effects arising from gluon saturation at high parton densities. They are similarly sensitive in these kinematics to large Sudakov logarithms from soft gluon radiation. Uncovering novel physics in this DIS channel therefore requires understanding the interplay of the two phenomena. In this work, we compute the small xBj inclusive dijet DIS cross-section in back-to-back kinematics at next-to-leading order (NLO) in the Color Glass Condensate effective field theory (CGC EFT). Our result includes, for the first time, all real and virtual NLO contributions to the impact factor. These include all Sudakov double and single logarithm contributions, as well as all other finite $$ \mathcal{O} $$ O (αs) terms that contribute at this order. We demonstrate explicitly that resummations of small x and Sudakov logarithms can be performed simultaneously in the CGC EFT. This requires that the JIMWLK kernel for small x evolution of the Weizsäcker-Williams (WW) gluon distribution satisfies a kinematic constraint imposed by lifetime ordering of successive gluon emissions; the corresponding modifications to the kernel, corresponding to resummations of large double transverse logarithms, are precisely of the type required to stabilize JIMWLK evolution beyond leading logarithmicaccuracy. We compute the azimuthal harmonics of the NLO back-to-back distributions and show their sensitivity to both the unpolarized and linearly polarized WW gluon distributions. Finally, we discuss how TMD factorization is broken by an emergent saturation scale at small x.

Forward & Far-Forward Heavy Hadrons with Jethad: A High-Energy Viewpoint

“…Further progress will also hinge on connecting our program with NLO investigations of far-forward semi-inclusive emissions within the framework of gluon saturation [437][438][439][440][441][442][443][444][445][446][447][448][449][450][451]. In this context, the influence of soft-gluon radiation on angular asymmetries in emissions of far-forward di-jet or di-hadron systems might be relevant [452][453][454][455][456][457]. Higher-order saturation permits to explore of the (un)polarized gluon content of protons and nucleons at low-x [458][459][460][461][462][463].…”

The QCD shockwave approach at NLO: towards precision physics in gluonic saturation

“…Besides, the number of processes for which the impact factors are known with a NLO accuracy is rather small. For inclusive processes, this list contains inclusive DIS [32][33][34], inclusive photoproduction of dijets [35,36], photon-dijet production in DIS [37], dijets in DIS [38,39], single hadron [40] and dihadrons production in DIS [41,42]. For diffractive processes, NLO impact factors are known for exclusive dijets [43][44][45] and exclusive light meson production [46,47], exclusive quarkonium production [48,49], and inclusive diffractive DIS [50].…”

Vector Quarkonia at the LHC with Jethad: A High-Energy Viewpoint

“…In these analyses, the influence of softgluon radiation on angular asymmetries in dijet or dihadron production was addressed (see Refs. [352,353,[421][422][423][424]).…”