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Related papers: A unity of QCD evolution dynamics at small $x$ reg…

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We give a brief overview of the perturbative QCD description of the proton deep-inelastic structure function F2(x, Q2) at small x. We discuss GLAP and BFKL approaches, and then we review progress towards a more unified treatment.

High Energy Physics - Phenomenology · Physics 2008-02-03 A. D. Martin

We investigate the evolution of parton densities at small values of the momentum fraction, x, by including resummed anomalous dimensions in the renormalization group equations. The resummation takes into account the leading-logarithmic…

High Energy Physics - Phenomenology · Physics 2016-09-01 R. K. Ellis , F. Hautmann , B. R. Webber

The proton spin puzzle is a longstanding problem in high-energy nuclear physics: how the proton spin distributes among the spin and orbital angular momenta of the quarks and gluons inside. Two of the unresolved pieces of the puzzle are the…

High Energy Physics - Phenomenology · Physics 2023-06-29 Yossathorn Tawabutr

I discuss radiative corrections to the BFKL equation for high energy cross sections in perturbative QCD. Due to the gluon Reggeization in the next-to-leading $\ln s$ approximation, the form of the BFKL equation remains unchanged and the…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. S. Fadin

We review small $x$ contributions to perturbative evolution equations for parton distributions, and their resummation. We emphasize in particular the resummation technique recently developed in order to deal with the apparent instability of…

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

We propose a matrix evolution equation in (x,kt)-space for flavour singlet, unintegrated quark and gluon densities, which generalizes DGLAP and BFKL equations in the relevant limits. The matrix evolution kernel is constructed so as to…

High Energy Physics - Phenomenology · Physics 2010-03-25 M. Ciafaloni , D. Colferai , G. P. Salam , A. M. Stasto

We present exploratory studies of the proton structure via two distinct kinds of gluon densities: the transverse-momentum dependent functions, whose evolution is determined by the CSS equation, and the unintegrated gluon distribution, whose…

High Energy Physics - Phenomenology · Physics 2022-10-18 Francesco Giovanni Celiberto

We summarize recent progress in the resummation of perturbative evolution at small x. We show that the problem of incorporating BFKL small x logs in GLAP evolution is now completely solved, and that the main effect of small x resummation is…

High Energy Physics - Phenomenology · Physics 2017-08-23 Stefano Forte , Guido Altarelli , Richard D. Ball

We present numerical studies of the leading non-linear corrections to the DGLAP evolution equations of parton distribution functions (PDFs) resulting from gluon recombination, which reduce the pace of evolution at small momentum fractions…

High Energy Physics - Phenomenology · Physics 2024-06-21 Pit Duwentäster , Vadim Guzey , Ilkka Helenius , Hannu Paukkunen

We present a set of formulas to extract two second-order independent differential equations for the gluon and singlet distribution functions. Our results extend from the LO up to NNLO DGLAP evolution equations with respect to the…

High Energy Physics - Phenomenology · Physics 2014-02-04 G. R. Boroun , B. Rezaei

A new approach to global QCD analysis is developed. The main ingredients are two QCD-based evolution equations. The first one is the Balitsky-Kovchegov nonlinear equation, which sums higher twists while preserving unitarity. The second…

High Energy Physics - Phenomenology · Physics 2014-11-17 E. Gotsman , E. Levin , M. Lublinsky , U. Maor

We indicate that the random aperiodic oscillation of the gluon distributions in a modified BFKL equation has the positive Lyapunov exponents. This first example of chaos in QCD evolution equations, raises the sudden disappearance of the…

High Energy Physics - Phenomenology · Physics 2008-05-01 Wei Zhu , Zhenqi Shen , Jianhong Ruan

We computed the longitudinal proton structure function $F_{L}$, using the nonlinear Dokshitzer-Gribov-Lipatov-Altarelli-parisi (NLDGLAP) evolution equation approach at small $x$. For the gluon distribution, the nonlinear effects are related…

High Energy Physics - Phenomenology · Physics 2014-02-07 G. R. Boroun

We show that it is possible to use hard-Pomeron behavior to the gluon distribution and singlet structure function at low $x$. We derive a second-order independent differential equation for the gluon distribution and the singlet structure…

High Energy Physics - Phenomenology · Physics 2014-02-05 B. Rezaei , G. R. Boroun

Aspects of the QCD parton densities are briefly reviewed, drawing some parallels to the density matrix formulation of quantum mechanics, exemplified by Wigner functions. We elaborate on the solution of their evolution equations using…

High Energy Physics - Phenomenology · Physics 2007-05-23 Alessandro Cafarella , Claudio Coriano' , Marco Guzzi

The QCD dipole picture allows to build an unified theoretical description -based on BFKL dynamics- of the total and diffractive nucleon structure functions measured at HERA. We use a four parameter fit to describe the 1994 H1 proton…

High Energy Physics - Phenomenology · Physics 2007-05-23 C. Royon

We numerically study for the first time the nonlinear GLR-MQ evolution equations for nuclear parton distribution function (nPDFs) to next-to-leading order accuracy and quantify the impact of gluon recombination at small $x$. Using the…

High Energy Physics - Phenomenology · Physics 2023-03-15 J. Rausch , V. Guzey , M. Klasen

We study the evolution of parton distributions down to low scales by considering several of their Mellin moments. For the initial conditions, we use a broad array of current parton density fits. Confirming earlier findings in the…

High Energy Physics - Phenomenology · Physics 2020-01-08 Markus Diehl , Pascal Stienemeier

This paper introduces a transverse-momentum dependent (TMD) factorization scheme designed to unify both large and small Bjorken-x regimes. We compute the next-to-leading order (NLO) quantum chromodynamics (QCD) corrections to the gluon TMD…

High Energy Physics - Phenomenology · Physics 2024-03-04 Swagato Mukherjee , Vladimir V. Skokov , Andrey Tarasov , Shaswat Tiwari

Evolution of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equation in next-to-leading order (NLO) at low-x is presented assuming the Regge behaviour of quarks and gluons at this limit. We…

High Energy Physics - Phenomenology · Physics 2010-03-25 U. Jamil , J. K. Sarma