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We present predictions for the spin structure functions of the proton and the neutron in the framework of a unitary isobar model for one-pion photo- and electroproduction. Our results are compared with recent experimental data from SLAC.…

Nuclear Theory · Physics 2007-05-23 L. Tiator , D. Drechsel , S. S. Kamalov

The structure function $g_1(x,Q^2)$ is analysed within the formalism based on unintegrated spin dependent parton distributions incorporating the LO Altarelli-Parisi evolution and the double $ln^2(1/x)$ resummation at low $x$. We…

High Energy Physics - Phenomenology · Physics 2014-11-17 J. Kwiecinski , B. Ziaja

For the generalized parton distribution (GPD) E, extracted from hard exclusive processes and the Pauli form factor of the nucleon, the second moments for quarks and gluons at $t=0$ are calculated and their scale dependence analyzed. The…

High Energy Physics - Phenomenology · Physics 2025-01-03 Peter Kroll

Following the operator definition of the fragmentation function developed by Collins and Soper, we compute the gluon-to-$h_c$ fragmentation function at the lowest order in the velocity expansion in NRQCD factorization approach. Utilizing…

High Energy Physics - Phenomenology · Physics 2020-07-29 Feng Feng , Saadi Ishaq , Yu Jia , Jia-Yue Zhang

This study explores the heavy-quark contributions to polarized structure functions in deep-inelastic scattering at next-to-leading order. The structure functions $g_1$, $g_4$, $g_5$, $g_6$, and $g_7$ are computed, while $g_2$ and $g_3$ are…

High Energy Physics - Phenomenology · Physics 2026-03-12 Edoardo Spezzano , Tomas Jezo , Michael Klasen , Ingo Schienbein

The running of the QCD coupling is incorporated into the infrared evolution equations for the flavour structure function g_1. The explicit expressions for g_1 including the total resummation of the double-logarithmic contributions and…

High Energy Physics - Phenomenology · Physics 2008-11-26 B. I. Ermolaev , M. Greco , S. I. Troyan

We estimate the Collins fragmentation function by introducing the effect of gluon rescattering in a model calculation of the fragmentation process. We include all necessary diagrams to the one-loop level and compute the nontrivial phases…

High Energy Physics - Phenomenology · Physics 2015-06-25 Alessandro Bacchetta , Andreas Metz , Jian-Jun Yang

We report on the extension of the data fitting considering the QCD inspired model based on the summation of gluon ladders applied to the $ep$ scattering. In lines of a two Pomeron approach, the structure function $F_2$ has a hard piece…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Lengyel , M. V. T. Machado

We calculate the $O(\alpha_s)$ and $O(\alpha_s^2)$ gluon radiative corrections to the QCD sum rule for the first Gegenbauer moment $a_1^K$ of the kaon light-cone distribution amplitude. The NNL0 accuracy is achieved for the perturbative…

High Energy Physics - Phenomenology · Physics 2008-11-26 K. G. Chetyrkin , A. Khodjamirian , A. A. Pivovarov

We derive here the equation of state for quark matter with a nontrivial vacuum structure in QCD at finite temperature and baryon density. Using thermofield dynamics, the parameters of thermal vacuum and the gluon condensate function are…

High Energy Physics - Phenomenology · Physics 2015-06-25 A. Mishra H. Mishra , S. P. Misra

Nucleon resonance contributions to the polarized proton $g_1$ and $g_2$ structure functions are computed from resonance electroexcitation amplitudes extracted from CLAS exclusive meson electroproduction data. Including resonances in the…

High Energy Physics - Phenomenology · Physics 2023-03-21 A. N. Hiller Blin , V. I. Mokeev , W. Melnitchouk

The structure function of the nucleus in the cumulative region $x>1$ is studied in terms of nucleon degrees of freedom. At high $Q^2$ the resulting expressions are presented as a sum of contributions from few-nucleon correlations.…

Nuclear Theory · Physics 2009-11-07 M. A. Braun , V. M. Suslov , B. Vlahovic

Contents: 1. The sum rules or $\Gamma_{p,n}$.Theoretical status. 2. Calculations of matrix elements over the polarized nucleon by the QCD sum rule approach. 3. Twist-4 corrections to $\Gamma_{p,n}$ from QCD sum rules. 4. Gerasimov,…

High Energy Physics - Phenomenology · Physics 2009-09-25 B. L. Ioffe

The generalized Gerasimov-Drell-Hearn (GDH) sum rule is known to be very sensitive to QCD radiative and power corrections. We improve the previously developed QCD-inspired model for the $Q^2$-dependence of the GDH sum rule. We take into…

High Energy Physics - Phenomenology · Physics 2010-10-27 Roman Pasechnik , Jacques Soffer , Oleg Teryaev

The proton spin dependent structure function $g_1^p$ is analysed using the unified scheme incorporating both Altarelli-Parisi evolution and the double $ln^2(1/x)$ effects at low $x$. The latter are found to be very important in the region…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Kwiecinski , B. Ziaja

Double-polarization asymmetries for inclusive $ep$ scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH$_3$ target in the CLAS detector. The polarized…

Nuclear Experiment · Physics 2010-04-06 R. Fatemi , A. V. Skabelin , V. D. Burkert , D. Crabb , R. De Vita , S. E. Kuhn , R. Minehart , CLAS Collaboration

We have estimated the contributions to the moments of polarized nucleon structure function $g_1(x,Q^2)$ coming from the region of the very low x ($10^{-5}<x$). Our approach uses the nucleon structure function extrapolated to the region of…

High Energy Physics - Phenomenology · Physics 2014-11-17 B. Ziaja

The method of truncated Mellin moments in a solving QCD evolution equations of the nonsinglet structure functions $F_2^{NS}(x,Q^2)$ and $g_1^{NS}(x,Q^2)$ is presented. All calculations are performed within double logarithmic $ln^2x$…

High Energy Physics - Phenomenology · Physics 2007-05-23 D. Kotlorz , A. Kotlorz

The first measurements of the diffractive structure function $F_2^{D(3)}$ at HERA are discussed. A factorisable interpretation in which a partonic structure is assigned to the pomeron is investigated through QCD analyses in which both the…

High Energy Physics - Phenomenology · Physics 2008-11-26 K. Golec-Biernat , J. P. Phillips

The fixed-mass sum rules for the deuteron target have been derived by using the connected matrix element of the current anti-commutation relation on the null-plane. From these sum rules we obtain the relation between the pseudo-scalar meson…

High Energy Physics - Phenomenology · Physics 2010-02-02 Susumu Koretune
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