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We present nonlinear (NL) and higher twist (HT) corrections to the color dipole model (CDM) bounds at low values of $x$ and $Q^{2}$ using the parameterization method. Consistency between the bounds at this region describe that a transition…

High Energy Physics - Phenomenology · Physics 2021-10-12 G. R. Boroun , B. Rezaei

We present exploratory studies of the proton content via unpolarized and polarized transverse-momentum-dependent gluon distributions in the proton at leading twist. We make use of an enhanced spectator-model approach to encode in our…

High Energy Physics - Phenomenology · Physics 2022-06-17 Alessandro Bacchetta , Francesco Giovanni Celiberto , Marco Radici

A fit is made to the data for the proton structure function up to Q^2=10 GeV^2, including the real gamma p total cross-section. It is economical and simple, and its form is motivated by physical principles. It is extrapolated down to very…

High Energy Physics - Phenomenology · Physics 2009-10-22 A Donnachie , P V Landshoff

Self-similarity based model of proton structure function at small \textit{x} was reported in the literature sometime back. The phenomenological validity of the model is in the kinematical region $ 6.2\, \times \, 10^{-7} \leq x \leq…

High Energy Physics - Phenomenology · Physics 2014-04-28 Akbari Jahan , D. K. Choudhury

In this work we have solved the nonlinear GLR-MQ evolution equation upto next-to-leading order (NLO) by considering NLO terms of the gluon-gluon splitting functions and running coupling constant $\alpha_s(Q^2)$. Here, we have incorporated a…

High Energy Physics - Phenomenology · Physics 2018-01-22 M. Lalung , P. Phukan , J. K. Sarma

Within a QCD-based eikonal model with a dynamical infrared gluon mass scale we discuss how the small $x$ behavior of the gluon distribution function at moderate $Q^{2}$ is directly related to the rise of total hadronic cross sections. In…

High Energy Physics - Phenomenology · Physics 2008-11-26 E. G. S. Luna , A. A. Natale , C. M. Zanetti

We study numerically the small-$x$ behaviour of the nuclear gluon distribution function $ G^A(x,Q^2)$ at next-to-leading order (NLO) approximation of the Gribov-Levin-Ryskin-Mueller-Qiu, Zhu-Ruan-Shen (GLR-MQ-ZRS) nonlinear equation and…

Nuclear Theory · Physics 2025-10-21 F. Abdi , B. Rezaei

We study of the accuracy of the Regge behavior of the gluon distribution function for obtain an approximation relation, which is frequently used to extract the logarithmic slopes of the structure function from the gluon distribution at…

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

Momentum sum rule can be used as an inequality to estimate the lower and upper bounds of the momentum fractions of quarks and gluons in a model of proton valid in a limited \textit{x} range. We compute such bounds in a self-similarity based…

High Energy Physics - Phenomenology · Physics 2013-06-21 Akbari Jahan , D K Choudhury

The distribution of the spin of the nucleon among its constituents can be parametrized in the form of polarized parton distribution functions for quarks and gluons. Using all available data on the polarized structure function $g_1(x,Q^2)$,…

High Energy Physics - Phenomenology · Physics 2014-11-17 T. Gehrmann , W. J. Stirling

The recent high precision SMC data on polarized $\mu p$ scatterings have again confirmed that very little of the proton spin is carried by quarks. To unravel the mystery of the proton spin structure, it is quite important to know the…

High Energy Physics - Phenomenology · Physics 2009-10-28 T. Morii , S. Tanaka , T. Yamanishi

A new measurement of the proton structure function $F_2(x,Q^2)$ is reported for momentum transfers squared $Q^2$ between 1.5 GeV$^2$ and 5000 GeV$^2$ and for Bjorken $x$ between $3\cdot 10^{-5}$ and 0.32 using data collected by the HERA…

High Energy Physics - Experiment · Physics 2010-03-25 S. Aid , H1 Collaboration

We study the structure functions $F_{k}^{b}(x,Q^{2})$ ($k=2, L$) and the reduced cross section $\sigma_{r}^{b}(x,Q^{2})$ for small values of Bjorken$^{,}$s $x$ variable with respect to the hard (Lipatov) pomeron for the gluon distribution…

High Energy Physics - Phenomenology · Physics 2014-06-03 G. R. Boroun

We evaluate the unintegrated gluon distribution of the proton starting from a parametrization of the color dipole cross section including DGLAP evolution and saturation effects. To this end, we perform the Fourier-Bessel transform of…

High Energy Physics - Phenomenology · Physics 2022-12-14 Agnieszka Łuszczak , Marta Łuszczak , Wolfgang Schäfer

New data, especially HERA measurements of the proton structure function at small $x$, allow the opportunity to improve our knowledge of the gluon and quark distribution functions. We perform a global analysis which incorporates these new…

High Energy Physics - Phenomenology · Physics 2009-07-09 A. D. Martin , R. G. Roberts , W. J. Stirling

I present a theoretical discussion of the uncertainties related to the QCD analysis of the proton structure function $F_2(x,Q^2)$ at small $x$. The role played by the `unphysical' gluon density is pointed out. It is shown how the study of…

High Energy Physics - Phenomenology · Physics 2008-11-26 Stefano Catani

Gluon distributions in real and virtual photons are calculated using evolution equations in the NLO approximation. The quark distributions in the photon determined on the basis of the QCD sum rule approach in ref.[1] are taken as an input.…

High Energy Physics - Phenomenology · Physics 2019-08-17 B. L. Ioffe , A. Oganesian

We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be derived within perturbative QCD at…

High Energy Physics - Phenomenology · Physics 2023-12-14 Guido Altarelli , Stefano Forte , Giovanni Ridolfi

An analytical solution of the QCD evolution equations for the singlet and gluon distribution is presented. We decouple DGLAP evolution equations into the initial conditions by using a Laplace transform method at $N^{n}LO$ analysis. The…

High Energy Physics - Phenomenology · Physics 2019-05-13 B. Rezaei , G. R. Boroun

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