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Related papers: Quark and Gluon Helicity Evolution at Small $x$: R…

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We extend our earlier results for the quark helicity evolution at small $x$ to derive the small-$x$ asymptotics of the flavor singlet and flavor non-singlet quark helicity TMDs and PDFs and of the $g_1$ structure function. In the flavor…

High Energy Physics - Phenomenology · Physics 2017-02-08 Yuri V. Kovchegov , Daniel Pitonyak , Matthew D. Sievert

We construct small-x evolution equations which can be used to calculate quark and anti-quark helicity TMDs and PDFs, along with the $g_1$ structure function. These evolution equations resum powers of $\alpha_s \, \ln^2 (1/x)$ in the…

High Energy Physics - Phenomenology · Physics 2016-07-15 Yuri V. Kovchegov , Daniel Pitonyak , Matthew D. Sievert

It is well-known that the back-to-back (correlation) limit of inclusive quark-antiquark dijet production in unpolarized high energy electron-proton collisions can probe the Weizs\"{a}cker-Williams (WW) gluon transverse momentum-dependent…

High Energy Physics - Phenomenology · Physics 2025-04-18 Yuri V. Kovchegov , Ming Li

The small-$x$ deep inelastic scattering in the saturation region is governed by the non-linear evolution of Wilson-line operators. In the leading logarithmic approximation it is given by the BK equation for the evolution of color dipoles.…

High Energy Physics - Phenomenology · Physics 2008-11-26 Ian Balitsky , Giovanni A. Chirilli

We analyze the world polarized deep-inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) data at low values of $x < 0.1$, using small-$x$ evolution equations for the flavor singlet and nonsinglet helicity parton distribution functions…

We generalize the JIMWLK evolution equation to include the small-$x$ evolution of helicity distributions. To derive helicity JIMWLK, we use the method devised by A.H. Mueller for the usual unpolarized JIMWLK, and apply it to the helicity…

High Energy Physics - Phenomenology · Physics 2019-12-18 Florian Cougoulic , Yuri V. Kovchegov

Noting that the number of gluons in the hadron wave function is discrete, and their formation in the chain of small-x evolution occurs over discrete rapidity intervals of Delta y~1/alpha_s, we formulate the discrete version of the…

High Energy Physics - Phenomenology · Physics 2015-06-25 Kirill Tuchin

We develop simple analytic representations of the polarized quark and gluon distributions in the nucleon at low $Q^2$ which incorporate general constraints obtained from the requirements of color coherence of gluon couplings at $x \sim 0$…

High Energy Physics - Phenomenology · Physics 2009-09-25 Stanley J. Brodsky , Matthias Burkardt , Ivan Schmidt

The number of gluons in the hadron wave function is discrete, and their formation in the chain of small $x$ evolution occurs over discrete rapidity intervals of $\Delta y \simeq 1/\as$. We therefore consider the evolution as a discrete…

High Energy Physics - Phenomenology · Physics 2011-01-25 Dmitri Kharzeev , Kirill Tuchin

We derive the first-ever small-$x$ expression for the inclusive gluon production cross section in the central rapidity region of the longitudinally polarized proton-proton collisions. The cross section depends on the polarizations of both…

High Energy Physics - Phenomenology · Physics 2024-03-12 Yuri V. Kovchegov , Ming Li

Color quadrupoles have been found to be important in the proper description of observables sensitive to the small-x regime in nuclei as well as in the operator definition of the Weizs\"acker-Williams gluon distribution. In this paper, we…

High Energy Physics - Phenomenology · Physics 2015-05-30 Fabio Dominguez , A. H. Mueller , Stéphane Munier , Bo-Wen Xiao

We show the new relationship [1] between the anomalous dimensions, resummed through next-to-next-to-leading-logarithmic order, in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations for the first Mellin moments…

High Energy Physics - Phenomenology · Physics 2018-11-14 Bernd A. Kniehl , Anatoly V. Kotikov

Transverse momentum integrated multiplicities in the central region of pp collisions at LHC energies satisfy Koba-Nielsen-Olesen scaling. We attempt to relate this finding to multiplicity distributions of soft gluons. KNO scaling emerges if…

High Energy Physics - Phenomenology · Physics 2012-09-20 Adrian Dumitru , Elena Petreska

We investigate the importance of unitarity corrections to parton evolution in heavy flavor production at the LHC. The gluon distribution is determined with a fit to HERA data applying a unified BFKL-DGLAP approach, in which the non-linear…

High Energy Physics - Phenomenology · Physics 2017-08-23 Krisztian Peters

In this paper t and x-evolutions of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this limit, are…

High Energy Physics - Phenomenology · Physics 2014-11-18 U. Jamil , J. K. Sarma

The scattering of a baryon consisting of three massive quarks is investigated in the high energy limit of perturbative QCD. A model of a relativistic proton-like wave function, dependent on valence quark longitudinal and transverse momenta…

High Energy Physics - Phenomenology · Physics 2014-11-18 J. Bartels , L. Motyka

In this work we aim to gain qualitative insight on the far-from-equilibrium behavior of the gluon plasma produced in the early stages of a heavy-ion collision. It was recently discovered arXiv:1810.10554 that the distribution functions of…

High Energy Physics - Phenomenology · Physics 2022-06-08 Jasmine Brewer , Bruno Scheihing-Hitschfeld , Yi Yin

We study the helicity distributions of light flavor quark-antiquark ($q \bar{q}$) pairs in the nucleon sea. The valence quarks are handled by adopting the light-cone SU(6) quark-spectator-diquark model and the sea $q \bar{q}$ pairs are…

High Energy Physics - Phenomenology · Physics 2018-09-12 Mengyun Liu , Bo-Qiang Ma

Two widely proposed kt-dependent gluon distributions in the small-x saturation regime are investigated using two particle back-to-back correlations in high energy scattering processes. The Weizsacker-Williams gluon distribution, interpreted…

High Energy Physics - Phenomenology · Physics 2011-02-01 Fabio Dominguez , Bo-Wen Xiao , Feng Yuan

We examine the $Q^2$ evolution of gluon polarization in polarized nucleons. As is well known, the evolution of $\alpha_s \Delta G(Q^2)$ is negligible for typical momentum transfer variations found in experimental deep inelastic scattering.…

High Energy Physics - Phenomenology · Physics 2009-10-30 S. J. Pollock