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The properties of the new analytic running coupling are investigated at the higher loop levels. The expression for this invariant charge, independent of the normalization point, is obtained by invoking the asymptotic freedom condition. It…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. V. Nesterenko , I. L. Solovtsov

The brief overview of the definite determinations of the QCD coupling constant $\alpha_s$ from the characteristics of deep-inelastic scattering processes is given.

High Energy Physics - Phenomenology · Physics 2008-02-03 Andrei L. Kataev

In contrast to perturbative QCD, the analytic QCD models have running coupling whose analytic properties correctly mirror those of spacelike observables. The discontinuity (spectral) function of such running coupling is expected to agree…

High Energy Physics - Phenomenology · Physics 2012-07-04 César Ayala , Carlos Contreras , Gorazd Cvetič

As a first step towards the complete calculation of deep-inelastic scattering at third order of massless perturbative QCD, we have computed the fermionic (nf) contributions to the flavour non-singlet structure functions in unpolarized…

High Energy Physics - Phenomenology · Physics 2009-11-07 J. A. M. Vermaseren , S. Moch , A. Vogt

We compute the complete third-order contributions to the coefficient functions for the longitudinal structure function F_L, thus completing the next-to-next-to-leading order (NNLO) description of unpolarized electromagnetic deep-inelastic…

High Energy Physics - Phenomenology · Physics 2010-04-05 S. Moch , J. A. M. Vermaseren , A. Vogt

We present the results of our QCD analysis for nonsinglet unpolarized quark distributions and structure function $F_2(x,Q^2)$. New parameterizations are derived for the nonsinglet quark distributions for the kinematic wide range of $x$ and…

High Energy Physics - Phenomenology · Physics 2008-12-25 Ali N. Khorramian , S. Atashbar Tehrani

The new theoretical input to the analysis of the experimental data of the CCFR collaboration for $F_3$ structure function of $\nu N$ deep inelastic scattering is considered. This input comes from the next-to-next-to-leading order…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. L. Kataev , G. Parente , A. V. Sidorov

The impact of the resummed next-to-leading logarithmic small-$x$ contributions to the anomalous dimension $\gamma_{gg}$ is evaluated for the unpolarized parton densities and structure functions of the nucleon. These new terms diminish the…

High Energy Physics - Phenomenology · Physics 2016-09-06 J. Blümlein , A. Vogt

We have used QCD and polarized deep-inelastic scattering data to construct x-dependent polarized parton distributions. These flavor dependent distributions evolve under the NLO DGLAP equations, satisfy positivity constraints and agree well…

High Energy Physics - Phenomenology · Physics 2007-05-23 Gordon P. Ramsey

I examine the solution of the BFKL equation with NLO corrections relevant for deep inelastic scattering. Particular emphasis is placed on the part played by the running of the coupling. It is shown that the solution factorizes into a part…

High Energy Physics - Phenomenology · Physics 2009-10-31 R. S. Thorne

We investigate the occurrence of power terms in the running QCD coupling by analysing non-perturbative measurements of alpha_s (p) at low momenta obtained from the lattice three-gluon vertex. Our exploratory study provides some evidence for…

High Energy Physics - Phenomenology · Physics 2007-05-23 G. Burgio , F. Di Renzo , C. Parrinello , C. Pittori

We report on the recent completion of the three-loop calculation of the soft anomalous dimension in massless gauge-theory scattering amplitudes. This brings the state-of-the-art knowledge of long-distance singularities in multi-leg QCD…

High Energy Physics - Phenomenology · Physics 2016-06-21 Einan Gardi , Øyvind Almelid , Claude Duhr

A next-to-next-to-leading order (NNLO) QCD calculation of gluon distribution function at small-x is presented. The gluon distribution function is explored analytically in the DGLAP approach by a Taylor expansion at small x as two first…

High Energy Physics - Phenomenology · Physics 2018-08-10 Mayuri Devee , J. K. Sarma

We consider the expansion of small-$x$ resummed DGLAP splitting functions at next-to-leading logarithmic (NLL) accuracy to four-loop order, namely next-to-next-to-next-to-leading order (N$^3$LO). From this, we extract the exact LL and NLL…

High Energy Physics - Phenomenology · Physics 2018-07-06 Marco Bonvini , Simone Marzani

We compute the coefficient function for the charge-averaged W^(+/-)-exchange structure function F_3 in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms,…

High Energy Physics - Phenomenology · Physics 2010-04-05 S. Moch , J. Vermaseren , A. Vogt

We discuss the large-x behaviour of the splitting functions P_qg and P_gq and of flavour-singlet coefficient functions, such as the gluon contributions C_2,g and C_L,g to the structure functions F_2,L, in massless perturbative QCD. These…

High Energy Physics - Phenomenology · Physics 2010-12-13 A. Vogt , G. Soar , S. Moch , J. A. M. Vermaseren

We formulate the momentum-space Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations for structure functions measurable in deeply inelastic scattering. We construct a six-dimensional basis of structure functions that…

High Energy Physics - Phenomenology · Physics 2025-01-20 Tuomas Lappi , Heikki Mäntysaari , Hannu Paukkunen , Mirja Tevio

The two-loop invariant (running) coupling of QCD is written in terms of the Lambert W function. The analyticity structure of the coupling in the complex Q^2-plane is established. The corresponding analytic coupling is reconstructed via a…

High Energy Physics - Phenomenology · Physics 2016-12-28 B. Magradze

We analyze two sets of specific functions, that/which form the basis of the nonpower asymptotic expansions both in the timelike and spacelike regions for single scale dependent QCD observables in the Shirkov--Solovtsov's Analytic…

High Energy Physics - Phenomenology · Physics 2007-05-23 B. A. Magradze

The off-diagonal parton-scattering channels $g+\gamma^*$ and $q+\phi^*$ in deep-inelastic scattering are power-suppressed near threshold $x\to 1$. We address the next-to-leading power (NLP) resummation of large double logarithms of $1-x$ to…

High Energy Physics - Phenomenology · Physics 2020-12-02 Martin Beneke , Mathias Garny , Sebastian Jaskiewicz , Robert Szafron , Leonardo Vernazza , Jian Wang