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Perturbative solutions for unpolarized QED parton distribution and fragmentation functions are presented explicitly in the next-to-leading logarithmic approximation. The scheme of iterative solution of QED evolution equations is described…

High Energy Physics - Phenomenology · Physics 2023-09-06 A. B. Arbuzov , U. E. Voznaya

The low $x$ behaviour of the gluon density $xg(x,\mu^2)$ at scale $\mu^2=2.4$ GeV$^2$ is determined using exclusive $J/\psi$ production data from HERA and LHCb within the framework of collinear factorisation at next-to-leading order (NLO).…

High Energy Physics - Phenomenology · Physics 2021-01-04 Chris A. Flett , Alan D. Martin , Misha G. Ryskin , Thomas Teubner

We study a parton shower description, based on a dipole picture, of the final state in electron-positron annihilation. In such a shower, the distribution function describing the inclusive probability to find a quark with a given energy…

High Energy Physics - Phenomenology · Physics 2009-05-29 Zoltan Nagy , Davison E. Soper

We present an evolution equation which simultaneously sums the leading BFKL and DGLAP logarithms for the integrated gluon distribution in terms of a single variable, namely the emission angle of the gluon. This form of evolution is…

High Energy Physics - Phenomenology · Physics 2014-10-07 E. G. de Oliveira , A. D. Martin , M. G. Ryskin

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

We study parton-branching solutions of QCD evolution equations and present a method to construct both collinear and transverse momentum dependent (TMD) parton densities from this approach. We work with next-to-leading-order (NLO) accuracy…

High Energy Physics - Phenomenology · Physics 2018-02-14 F. Hautmann , H. Jung , A. Lelek , V. Radescu , R. Zlebcik

A nonlinear inequality is formulated in the paper. An estimate of the rate of growth/decay of solutions to this inequality is obtained. This inequality is of interest in a study of dynamical systems and nonlinear evolution equations. It can…

Classical Analysis and ODEs · Mathematics 2010-01-29 N. S. Hoang , A. G. Ramm

We present a generalization of the $x$-space $\texttt{Candia}$ algorithm to next-to-next-to-next-to-leading order (N$^3$LO) accuracy in Quantum Chromodynamics (QCD) for solving the DGLAP evolution equations for unpolarized parton densities…

High Energy Physics - Phenomenology · Physics 2026-03-24 Casey Hampson , Marco Guzzi

In order to explain a striking symmetry of the HERA data for virtual photon-proton cross section, I propose a simple model based on the elementary 2-gluon exchange dipole-dipole cross section, and which exhibits geometric scaling. I also…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. Munier

We analytically solved the QED $\otimes$ QCD coupled DGLAP evolution equations at leading order (LO) quantum electrodynamics (QED) and next to leading order (NLO) quantum chromodynamics (QCD) approximations, using the Laplace transform…

High Energy Physics - Phenomenology · Physics 2017-07-07 Marzieh Mottaghizadeh , Parvin Eslami , Fatemeh Taghavi-Shahri

The asymptotic collinear factorisation theorem, which holds for diffractive deep-inelastic scattering, has important modifications in the sub-asymptotic HERA regime. We use perturbative QCD to quantify these modifications. The diffractive…

High Energy Physics - Phenomenology · Physics 2010-03-25 A. D. Martin , M. G. Ryskin , G. Watt

We present a general method for the solution of the renormalization group equations for the non-forward parton distributions on the two-loop level in the flavour singlet channel based on an orthogonal polynomial reconstruction. Using this…

High Energy Physics - Phenomenology · Physics 2009-10-31 A. V. Belitsky , D. Müller , L. Niedermeier , A. Schäfer

We propose a new approach to the study of (nonlinear) growth and instability for semilinear evolution equations with compact nonlinearities. We show, in particular, that compact nonlinear perturbations of a linear evolution equation can be…

Analysis of PDEs · Mathematics 2023-09-27 Vladimir Müller , Roland Schnaubelt , Yuri Tomilov

I present a highly efficient method for evolving parton distributions in perturbative QCD. The method allows evolving the parton distribution functions according to any of the commonly-used truncations of the evolution equations (which…

High Energy Physics - Phenomenology · Physics 2014-11-17 David A. Kosower

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

We describe the gluon parton distribution function (PDF) in the proton, deduced by data from the ATLAS and HERA experiments, in the framework of the parton statistical model. The best fit parameters involved in the Planck formula that…

High Energy Physics - Phenomenology · Physics 2023-07-12 Loredana Bellantuono , Roberto Bellotti , Franco Buccella

We show how it is possible to rewrite the BFKL equation for the unintegrated gluon distribution, in terms of integrated gluons, similar to that used in DGLAP. We add to our equation the next-to-leading log terms which provide exact…

High Energy Physics - Phenomenology · Physics 2015-06-19 E. G. de Oliveira , A. D. Martin , M. G. Ryskin

The solution of DGLAP evolution equation for the twist-3 gluon operators is obtained in the Double Logarithmic Approximation of QCD perturbation theory. The method used for the solution is similar to the reggeon field theory. The…

High Energy Physics - Phenomenology · Physics 2014-11-17 A. G. Shuvaev

Study of parton distribution function (PDF) is a topic of significant interest in QCD. To overcome the shortcomings of conventional PDFs, several alternative methods have been suggested in recent years. The present work reports the x…

High Energy Physics - Phenomenology · Physics 2009-10-14 D. K. Choudhury , Pijush Kanti Dhar

Collinear and transverse momentum dependent (TMD) parton densities are obtained from fits to precision measurements of deep inelastic scattering (DIS) cross sections at HERA. The parton densities are evolved by DGLAP evolution with…

High Energy Physics - Phenomenology · Physics 2019-04-17 A. Bermudez Martinez , P. Connor , F. Hautmann , H. Jung , A. Lelek , V. Radescu , R. Zlebcik