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Related papers: Low x double $ln^2(1/x)$ resummation effects at th…

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Fits to the final combined HERA deep-inelastic scattering cross-section data within the conventional DGLAP framework of QCD have shown some tension at low $x$ and low $Q^2$. A resolution of this tension incorporating $\ln(1/x)$-resummation…

In this contribution, I present a new QCD fit to final combined HERA deep-inelastic scattering cross-section data incorporating $\ln(1/x)$-resummation terms. This fit has been performed within the xFitter framework. The main effect of…

High Energy Physics - Phenomenology · Physics 2018-05-07 Francesco Giuli

We derive an equation determining the small-x evolution of the F_2 structure function of a large nucleus which includes all multiple pomeron exchanges in the leading logarithmic approximation using Mueller's dipole model. We show that in…

High Energy Physics - Phenomenology · Physics 2014-11-17 Yuri V. Kovchegov

We report the results of including resummed splitting functions in the QCD evolution equations at small x, and discuss the predictions that follow for the deep inelastic structure functions. *Contribution at XXX Rencontres de Moriond, Les…

High Energy Physics - Phenomenology · Physics 2016-09-01 F. Hautmann

In the collinear factorization of the form factor for the transition $\gamma^* \pi^0 \to \gamma$ the hard part contains double log terms as $\ln^2 x$ with $x$ as the momentum fraction of partons from 0 to 1. A simple exponentiation for…

High Energy Physics - Phenomenology · Physics 2009-11-13 F. Feng , J. P. Ma , Q. Wang

The small-$x$ contributions to the Bjorken sum rule within unified picture $ln^2x+$LO DGLAP for different input parametrisations $g_1^{NS}(x,Q_0^2)$ are presented. Theoretical predictions for $\int_{0}^{0.003} g_1^{NS}(x,Q^2=10) dx$ are…

High Energy Physics - Phenomenology · Physics 2014-11-18 D. Kotlorz , A. Kotlorz

Small-$x$ logarithmic enhancements arising from high-energy gluon emissions affect both the evolution of collinearly-factorized parton densities and partonic coefficient functions. With the higher collider energy reached by the LHC, the…

High Energy Physics - Phenomenology · Physics 2016-11-04 Marco Bonvini , Simone Marzani , Tiziano Peraro

The generalized Baldin sum rule at finite four-momentum transfer Q^2 is evaluated utilizing a structure function parameterization fit to recent experimental data. The most recent measurements on F_1 from Hall C at Jlab, as well as the F_2…

Nuclear Theory · Physics 2014-02-03 A. Sibirtsev , P. G. Blunden

A brief survey is given of recent results on the resummation of leading small-x terms for unpolarized and polarized non--singlet and singlet structure function evolution.

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Blümlein , S. Riemersma , A. Vogt

The combination g_1^p(x) - g_1^n(x) is derived from SLAC data on polarized proton and deuteron targets, evaluated at Q^2 = 10 GeV^2, and compared with the results of SMC experiment. The agreement is satisfactory except for the points at the…

High Energy Physics - Phenomenology · Physics 2015-06-25 F. Buccella , O. Pisanti , P. Santorelli

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

The nonsinglet spin dependent structure function $g_2(x,Q^2)$ is studied at small x within the double logarithmic approximation of perturbative QCD. Both positive and negative signature contributions are considered, and we find a power-like…

High Energy Physics - Phenomenology · Physics 2009-10-31 J. Bartels , M. G. Ryskin

The gluon contributions to $F_L(x,Q^2)$ in ${\cal O}(\alpha_s)$ are calculated taking into account the transverse momentum of the initial state parton. In comparison with collinear factorization $F_L(x,Q^2)$, is not affected at large $x$…

High Energy Physics - Phenomenology · Physics 2009-10-28 Johannes Blümlein

We calculate single-logarithmic corrections to the small-$x$ flavor-singlet helicity evolution equations derived recently in the double-logarithmic approximation. The new single-logarithmic part of the evolution kernel sums up powers of…

High Energy Physics - Phenomenology · Physics 2022-04-08 Yuri V. Kovchegov , Andrey Tarasov , Yossathorn Tawabutr

The reanalysis of all available world data on the longitudinal asymmetry A|| is presented. The proton structure function g1 was extracted within a unique framework of data inputs and assumptions. These data allowed for a reliable evaluation…

High Energy Physics - Experiment · Physics 2017-08-23 M. Osipenko , S. Simula , P. Bosted , V. Burkert , E. Christy , K. Griffioen , C. Keppel , S. Kuhn , G. Ricco

We present calculation of F_L in the double-logarithmic approximation and demonstrate that the synergic effect of the factor 1/x from the \alpha_s^2-order and the steep x-dependence of the totally resummed double logarithmic contributions…

High Energy Physics - Phenomenology · Physics 2021-04-14 B. I. Ermolaev , S. I. Troyan

We extend our previous results on small-x resummation in the pure Yang--Mills theory to full QCD with nf quark flavours, with a resummed two-by-two matrix of resummed quark and gluon splitting functions. We also construct the corresponding…

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

This talk reviews some recent results on the NLL resummed small-x gluon splitting function, as determined including renormalisation-group improvements. It also discusses the observation that the LO, NLO, NNLO, etc. hierarchy for the gluon…

High Energy Physics - Phenomenology · Physics 2009-11-10 Gavin P. Salam

We apply our systematic NLO small x resummation of singlet splitting functions to the scaling violations of structure functions and compare the results with data. We develop various theoretical tools which are needed in order to relate…

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

The Q^2 dependence of inclusive electron-proton scattering F_2 structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)^2, is investigated. Moments of F_2 are…

High Energy Physics - Phenomenology · Physics 2014-11-17 C. S. Armstrong , R. Ent , C. E. Keppel , S. Liuti , G. Niculescu , I. Niculescu