scholarly journals TMD gluon distributions at small x in the CGC theory

2018 ◽  
Vol 27 (05) ◽  
pp. 1830003 ◽  
Author(s):  
Elena Petreska
Keyword(s):  
Transverse Momentum ◽  
Recent Progress ◽  
Effective Theory ◽  
Color Glass ◽  
Color Glass Condensate ◽  
Transverse Momentum Dependent ◽  
Small X ◽  
Gluon Saturation ◽  
Gluon Distributions ◽  
Domain Of Validity

In this paper, we review recent progress in the description of unpolarized transverse-momentum-dependent (TMD) gluon distributions at small [Formula: see text] in the color glass condensate (CGC) effective theory. We discuss the origin of the nonuniversality of TMD gluon distributions in the TMD factorization framework and in the CGC theory and the equivalence of the two approaches in their overlapping domain of validity. We show some applications of this equivalence, including recent results on the behavior of TMD gluon distributions at small [Formula: see text], and on the study of gluon saturation. We discuss recent advances in the unification of the TMD evolution and the nonlinear small-[Formula: see text] evolution of gluon distributions.

scholarly journals Photons as Probes of Gluon Saturation in DiluteDense Collisions

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 33
Author(s):  
Sanjin Benić ◽  
Kenji Fukushima ◽  
Oscar Garcia-Montero ◽  
Raju Venugopalan
Keyword(s):  
Cross Section ◽  
Center Of Mass ◽  
Effective Field ◽  
Photon Production ◽  
Color Glass ◽  
Leading Order ◽  
Small X ◽  
Gluon Saturation ◽  
Gluon Distributions ◽  
Good Agreement

We use the Color Glass Condensate (CGC) effective field theory (EFT) to calculate inclusive photon production to leading order q g → q γ , (LO), and next-to leading order g g → q q ¯ γ (NLO) at LHC energies. These processes dominate the photon production at small-x , where x ≲ 0 . 01 in the target and projectile protons. We show that the NLO contribution dominates at values of x typical at the LHC, since its cross-section is sensitive to the gluon distributions in both protons. We perform a comparison of our results to the available inclusive photon data, from ATLAS and CMS at center-of-mass energies of 2 . 76 and 7 TeV . This data lies in the range k ⊥ > 20 GeV . We show that for this range, the k ⊥ -factorized cross-section converges to the full CGC EFT result, and can be used for the comparison. We find that it gives good agreement with experimental results. Our results are to be considered as a first step towards constraining unintegrated gluon distributions, which will be continued for larger systems, where coherent scatterings are enhanced.

scholarly journals SMALL x PHYSICS AND RHIC DATA

2011 ◽  
Vol 20 (01) ◽  
pp. 1-43 ◽  
Author(s):  
T. LAPPI
Keyword(s):  
Recent Progress ◽  
Initial Conditions ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Color Glass ◽  
Color Glass Condensate ◽  
Ion Collisions ◽  
Initial Stage ◽  
Small X ◽  
Rhic Data

This is a review of applications of the Color Glass Condensate (CGC) to the phenomenology of relativistic heavy-ion collisions. The initial stages of the collision can be understood in terms of the nonperturbatively strong nonlinear glasma color fields. We discuss how the CGC framework can and has been used to compute properties of the initial conditions of AA collisions. In particular this has led to recent progress in understanding multiparticle correlations, which can provide a directly observable signal of the properties of the initial stage of the collision process.

scholarly journals The gluon structure of hadrons and nuclei from lattice QCD

2018 ◽  
Vol 175 ◽  
pp. 01015
Author(s):  
Phiala Shanahan
Keyword(s):  
Transverse Momentum ◽  
Lattice Qcd ◽  
Degrees Of Freedom ◽  
Form Factors ◽  
Light Nuclei ◽  
Transverse Momentum Dependent ◽  
Gluon Distributions

I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon’s momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.

scholarly journals Transverse momentum dependent parton distributions at small-x

2017 ◽  
Vol 921 ◽  
pp. 104-126 ◽  
Author(s):  
Bo-Wen Xiao ◽  
Feng Yuan ◽  
Jian Zhou
Keyword(s):  
Transverse Momentum ◽  
Parton Distributions ◽  
Transverse Momentum Dependent ◽  
Small X

scholarly journals Effect of non-eikonal corrections on azimuthal asymmetries in the color glass condensate

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Pedro Agostini ◽  
Tolga Altinoluk ◽  
Néstor Armesto
Keyword(s):  
Transverse Momentum ◽  
Large Hadron Collider ◽  
Collision Energy ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Color Glass ◽  
Model Parameters ◽  
Color Glass Condensate ◽  
Relativistic Heavy Ion Collider ◽  
Azimuthal Asymmetries

Abstract We analyse the azimuthal structure of two gluon correlations in the color glass condensate including those effects that result from relaxing the shockwave approximation for the target. Working in the Glasma graph approach suitable for collisions between dilute systems, we compute numerically the azimuthal distributions and show that both even and odd harmonics appear. We study their dependence on model parameters, energy of the collision, pseudorapidity and transverse momentum of the produced particles, and length of the target. While the contribution from non-eikonal corrections vanishes with increasing collision energy and becomes negligible at the energies of the Large Hadron Collider, it is found to be sizeable up to top energies at the Relativistic Heavy Ion Collider.

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