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We present numerical solutions of the $Q^2$ evolution equations at next-to-leading order (NLO) for unpolarized and polarized parton distributions, in both the flavor non-singlet and singlet channels. The numerical method is based on a…

High Energy Physics - Phenomenology · Physics 2009-10-28 T. Weigl , W. Melnitchouk

Recently we obtained an evolution equation of gluon TMDs, which addresses a problem of unification of different kinematic regimes. It describes evolution in the whole range of Bjorken $x_B$ and the whole range of transverse momentum…

High Energy Physics - Phenomenology · Physics 2015-10-26 Andrey Tarasov

We summarize our recent result for a splitting function for small x evolution which includes resummed small x logarithms deduced from the leading order BFKL equation with the inclusion of running coupling effects. We compare this improved…

High Energy Physics - Phenomenology · Physics 2007-05-23 Guido Altarelli , Richard D. Ball , Stefano Forte

The corrections of gluon fusion to the DGLAP and BFKL equations are discussed in a united partonic framework. The resulting nonlinear evolution equations are the well-known GLR-MQ-ZRS equation and a new evolution equation. Using the…

High Energy Physics - Phenomenology · Physics 2016-08-08 Wei Zhu , Zhenqi Shen , Jianhong Ruan

A survey is given of recent developments on the resummed small-$x$ evolution, in a framework based on the renormalization group equation, of non--singlet and singlet structure functions in both unpolarized and polarized deep--inelastic…

High Energy Physics - Phenomenology · Physics 2015-06-25 J. Blümlein , S. Riemersma , A. Vogt

We study how the rapidity evolution of gluon transverse momentum dependent distribution changes from nonlinear evolution at small $x \ll 1$ to linear evolution at moderate $x \sim 1$.

High Energy Physics - Phenomenology · Physics 2015-09-30 I. Balitsky , A. Tarasov

We compare two Monte Carlo implementations of resummation schemes for the description of parton evolution at small values of Bjorken x. One of them is based on the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution equation and generates fully…

High Energy Physics - Phenomenology · Physics 2015-03-18 G. Chachamis , M. Deak , A. Sabio Vera , P. Stephens

We study how much gluon shadowing can be perturbatively generated through the modified QCD evolution in heavy nuclei. The evolution of small-$x$ gluons is investigated within the semiclassical approximation. The method of characteristics is…

Nuclear Theory · Physics 2010-11-01 K. J. Eskola , Jianwei Qiu , Xin-Nian Wang

We discuss perturbative evolution of the polarized structure function g_1 in the (x,Q^2) plane, with special regard to the small-x region. We determine g_1 in terms of polarized quark and gluon distributions using coefficient functions to…

High Energy Physics - Phenomenology · Physics 2009-10-28 R. D. Ball , S. Forte , G. Ridolfi

We explore several models of QCD evolution equations simplified by considering only the rapidity dependence of dipole scattering amplitudes, while provisionally neglecting their dependence on transverse coordinates. Our main focus is on the…

High Energy Physics - Phenomenology · Physics 2009-11-11 P. Rembiesa , A. M. Stasto

An approximated solution for gluon distribution from DGLAP evolution equations with NLO splitting function in the small-$x$ limit is presented. We first obtain the simplified forms of LO and NLO splitting functions in the small-$x$ limit.…

High Energy Physics - Phenomenology · Physics 2024-01-29 Jingxuan Chen , Xiaopeng Wang , Yanbing Cai , Xurong Chen , Qian Wang

The evolution of polarized quark distribution functions is taken into account the gluon emission and absorption, quark pair production and annihilation processes and treated by a statistical method which provides quark distribution…

High Energy Physics - Phenomenology · Physics 2016-09-06 Hai Lin

In the QCD the small~$x$ evolution of the interacting pomerons and odderons is studied with all angular momenta $l$ taken into account. The resulting system of coupled nonlinear evolution equations is formulated in the momentum space and…

High Energy Physics - Phenomenology · Physics 2020-05-25 M. A. Braun

We utilise the fact that the CCFM equation in the single loop approximation can be diagonalised by the Fourier-Bessel transform. The analytic solution of the CCFM equation for the moments $f_{\omega}(b,Q)$ of the scale dependent gluon…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Kwiecinski

Using Laplace transform techniques, we describe the evolution of the color dipole cross section, at the leading-order and next-to-leading order approximations, from the Bartels-Golec-Biernat-Kowalski model in a kinematical region of low…

High Energy Physics - Phenomenology · Physics 2024-10-01 G. R. Boroun

The evolution and the statistical properties of an infinite gravitating system represent an interesting and widely investigated subject of research. In cosmology, the standard approach is based on equations of hydrodynamics. In the present…

Statistical Mechanics · Physics 2009-11-07 L. Pietronero , M. Bottaccio , R. Mohayaee , M. Montuori

The conventional and linearly polarized Weizs\"acker-Williams gluon distributions at small x are defined from the two-point function of the gluon field in light-cone gauge. They appear in the cross section for dijet production in deep…

High Energy Physics - Phenomenology · Physics 2018-03-14 Adrian Dumitru , Vladimir Skokov

We propose an improvement of the splitting functions at small x which overcomes the apparent problems encountered by the BFKL approach. We obtain a stable expansion for the x-evolution function chi(M) near M=0 by including in it a sequence…

High Energy Physics - Phenomenology · Physics 2008-11-26 Guido Altarelli , Richard D. Ball , Stefano Forte

We consider a nonlinear evolution equation recently proposed to describe the small-$x$ hadronic physics in the regime of very high gluon density. This is a functional Fokker-Planck equation in terms of a classical random color source, which…

High Energy Physics - Phenomenology · Physics 2009-10-31 Edmond Iancu , Andrei Leonidov , Larry McLerran

QCD evolution equations can be recast in terms of parton branching processes. We present a new numerical solution of the equations. We show that this parton-branching solution can be applied to analyze infrared contributions to evolution,…

High Energy Physics - Phenomenology · Physics 2017-08-23 F. Hautmann , H. Jung , A. Lelek , V. Radescu , R. Zlebcik