Abstract
We compute the differential yield for quark anti-quark dijet production in high-energy electron-proton and electron-nucleus collisions at small x as a function of the relative momentum P⊥ and momentum imbalance k⊥ of the dijet system for different photon virtualities Q2, and study the elliptic and quadrangular anisotropies in the relative angle between P⊥ and k⊥. We review and extend the analysis in [1], which compared the results of the Color Glass Condensate (CGC) with those obtained using the transverse momentum dependent (TMD) framework. In particular, we include in our comparison the improved TMD (ITMD) framework, which resums kinematic power corrections of the ratio k⊥ over the hard scale Q⊥. By comparing ITMD and CGC results we are able to isolate genuine higher saturation contributions in the ratio Qs/Q⊥ which are resummed only in the CGC. These saturation contributions are in addition to those in the Weizsäcker-Williams gluon TMD that appear in powers of Qs/k⊥. We provide numerical estimates of these contributions for inclusive dijet production at the future Electron-Ion Collider, and identify kinematic windows where they can become relevant in the measurement of dijet and dihadron azimuthal correlations. We argue that such measurements will allow the detailed experimental study of both kinematic power corrections and genuine gluon saturation effects.
Highlights
In the past decades, high energy collider experiments have successfully verified that quantum chromodynamics (QCD) is the theory of strong interactions of quarks and gluons inside hadrons and nuclei
We review and extend the analysis in [1], which compared the results of the Color Glass Condensate (CGC) with those obtained using the transverse momentum dependent (TMD) framework
In order to single out the effect of genuine higher twists, we study the ratio of TMD to CGC near the back-to-back configuration k⊥ ≈ 0, where kinematic power corrections vanish
Summary
High energy collider experiments have successfully verified that quantum chromodynamics (QCD) is the theory of strong interactions of quarks and gluons (partons) inside hadrons and nuclei. The CGC has been applied for a variety of processes in proton-nucleus collisions as well as DIS: structure functions (inclusive [23, 24] and diffractive [25]), semi-inclusive production (photon [26,27,28,29], inclusive single hadron [30,31,32,33,34], dihadron/dijet [35,36,37,38], quarkonia [39,40,41,42]), and exclusive processes (deeply virtual Compton scattering and vector meson [43,44,45,46,47,48,49,50,51], dijet [52,53,54,55], trijet [56,57,58] production) to name a few (for a recent review see [59]) Among these various processes, forward particle azimuthal angle correlations are powerful observables to access the small-x structure of hadrons and nuclei at current and future collider experiments [60].
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have