We study dijet production in pA collisions at forward rapidities at next-to-eikonal accuracy. We restrict ourselves to the next-to-eikonal corrections that are induced by the quark background field of the target. We consider all possible channels, compute scattering amplitudes both in general kinematics and in the back-to-back limit. By using these results, we compute the back-to-back production cross section and obtain a factorized expression with a quark TMD times associated hard factor for each channel.

Poland

Tolga Altinoluk

Guillaume Beuf

Etienne Blanco

Swaleha Mulani

Quark TMDs from back-to-back dijet production at forward rapidities in pA collisions beyond eikonal accuracy in the CGC

<p>We derive the full next-to-eikonal (NEik) corrections to the gluon propagator from before to after traversing a highly boosted gluon background field, including corrections both beyond the shockwave limit and beyond the static limit in particular. After summarizing the results of the full NEik corrections to the before-to-after quark propagator computed in our earlier works, we also derive the before-to-inside, inside-to-inside, and inside-to-after quark and gluon propagators, which are building blocks to calculate high-energy scattering processes at NEik order. Using these results and also including the NEik corrections that stem from interactions with the target via t-channel quark exchanges, we compute inclusive cross sections for quark and gluon production at forward rapidities in quark-nucleus and gluon-nucleus scatterings at NEik accuracy.</p>

Forward parton-nucleus scattering at next-to-eikonal accuracy in the color glass condensate

We consider dijet production in deep inelastic scattering at small <math><mi>x</mi></math>, on a purely gluonic unpolarized target. Starting from earlier results obtained at next-to-eikonal accuracy in the high-energy limit, we perform the expansion in the back-to-back dijet limit, at next-to-leading power accuracy. We rewrite our results in the language of transverse-momentum-dependent (TMD) factorization, in terms of twist-2 and twist-3 TMD gluon distributions (gluon TMDs). Among the next-to-eikonal corrections, we find in particular twist-2 contributions corresponding to the <math><mi>x</mi></math> dependent phase of the twist-2 gluon TMDs. We also find two types of twist-3 unpolarized gluon TMDs, as well as correlators of three gluon field strength tensors.

Alina Czajka

France

Cyrille Marquet

Back-to-back dijet production in DIS at next-to-eikonal accuracy and twist-3 gluon TMDs

We compute the transverse and longitudinal diffractive structure functions to full next-to-leading order accuracy in the dipole picture of deep inelastic scattering. Our calculation uses the standard light-cone perturbation theory method for the partonic content of the virtual photon, together with the Color Glass Condensate description of the target color field. Our result includes as a subset the  $$q\overline{q }g$$  contribution calculated earlier. We show that there is a rapidity divergence that can be factorized into the BK/JIMWLK evolution of the target Wilson lines, and that all other divergences cancel.

Finland

Tuomas Lappi

Heikki Mäntysaari

Risto Paatelainen

United States

Jani Penttala

Diffractive deep inelastic scattering at NLO in the dipole picture

Various conventional running coupling prescriptions reproducing β 0-dependent terms of NLO JIMWLK are reviewed and found to be theoretically inconsistent: the JIMWLK evolution Hamiltonian with running coupling violates the requirement of positive semidefiniteness. This requirement appears to be tightly related to the possibility of having a Langevin formulation for the evolution.

Israel

Michael Lublinsky

Vladimir Skokov

On running coupling in the JIMWLK evolution and its Langevin formulation

We study the production, in deep inelastic scattering at high energy, of a quark-gluon dijet induced by <math><mi>t</mi></math>-channel quark exchange with the target, which goes beyond the eikonal approximation. Throughout this study we follow the color glass condensate approach, keep full dependence on the quark mass and consider the target to be unpolarized. We focus on the correlation limit in which the produced jets fly almost back-to-back and find a factorized expression for the cross section, for both longitudinal and transverse photons, involving the unpolarized quark transverse momentum dependent distribution. Quark-gluon dijets can be distinguished from other types of dijets at least in the heavy quark case, thanks to heavy flavor tagging. In that case, the dominant background is expected to come from the eikonal production of a quark-antiquark-gluon system. We propose experimental cuts to suppress that background contribution, making the process of quark-gluon dijet production in deep inelastic scattering a new method to probe the quark transverse momentum dependent distribution at the Electron Ion Collider.

Spain

Néstor Armesto

Probing quark transverse momentum distributions in the color glass condensate: Quark-gluon dijets in deep inelastic scattering at next-to-eikonal accuracy

We compute dijet production in deep inelastic scattering at low <math><mi>x</mi></math> in the dipole formalism at next-to-eikonal accuracy. We calculate the contributions induced by single photon exchange of either longitudinal or transverse polarization. We include all types of corrections to the eikonal approximation in the gluon background field: (i) finite longitudinal width of the target, (ii) interaction of the quark-antiquark pair with the subleading (transverse) component of the background field, and (iii) dynamics of the target which is encoded in the <math><msup><mi>z</mi><mo>−</mo></msup></math>-coordinate dependence of the background field. The final expressions for the dijet cross section are written as the sum of a “generalized eikonal” contribution (where the longitudinal momentum <math><msup><mi>p</mi><mo>+</mo></msup></math> exchange between the target and the incoming quark-antiquark pair is allowed since the average <math><msup><mi>z</mi><mo>−</mo></msup></math> dependence of the background field is kept) and explicit next-to-eikonal corrections that involve decorated dipole and quadrupole operators.

Arantxa Tymowska

DIS dijet production at next-to-eikonal accuracy in the CGC

We compute the cross section for the inclusive photoproduction of a pair of jets at next-to-leading order accuracy in the Color Glass Condensate (CGC) effective theory. The aim is to study the back-to-back limit, to investigate whether transverse momentum dependent (TMD) factorization can be recovered at this perturbative order. In particular, we focus on large Sudakov double logarithms, which are dominant terms in the TMD evolution kernel. Interestingly, the kinematical improvement of the low-x resummation scheme turns out to play a crucial role in our analysis.

Belgium

Pieter Taels

Dijet photoproduction at low x at next-to-leading order and its back-to-back limit

We revisit the calculation of quark and scalar propagators in a gluon background field at next-to-eikonal accuracy, which will provide the first power correction to scattering processes in the high-energy limit, including gluon saturation effects. The two main results of our study are as follows. First, we derive a very general next-to-eikonal expansion of the quark propagator in terms of the scalar propagator, which allows us to isolate spinor-specific next-to-eikonal corrections from the universal ones. Second, we present a new method allowing, for the first time, a systematic calculation of the next-to-eikonal corrections coming from the <math><msup><mi>x</mi><mo>−</mo></msup></math> dependence of the background field. This opens the possibility to study high-energy scattering processes on a target with nontrivial dynamics instead of on a static one, by going beyond infinite Lorentz time dilation of the target.

Quark and scalar propagators at next-to-eikonal accuracy in the CGC through a dynamical background gluon field

We derive next-to-eikonal (NEik) corrections to the background quark propagator, which stem from (i) considering a finite longitudinal width target instead of an infinitely thin shockwave and (ii) including the interaction of the quark with the transverse components of the background field. These two different corrections to the eikonal approximation combine together and provide a gauge covariant expression for the quark propagator at NEik accuracy. We then apply our results to quark (or antiquark) scattering on a nucleus at NEik accuracy, considering both unpolarized cross section and helicity asymmetry.