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We report a semi-analytical approach for the solution of the nonlinear Gribov-Levin-Ryskin-Mueller-Qiu (GLR-MQ) evolution equation for sea quark distribution and investigate the effect of gluon shadowing on the small-x and moderate-Q^2…

High Energy Physics - Phenomenology · Physics 2018-08-09 Mayuri Devee

Theoretical predictions show that at low values of Bjorken $x$ the spin structure function, $g_1$ is influenced by large logarithmic corrections, $ln^2(1/x)$, which may be predominant in this region. These corrections are also partially…

High Energy Physics - Phenomenology · Physics 2014-11-17 Beata Ziaja

Explicit expressions for the non-singlet and singlet structure functions g_1 at the small $x$-region are obtained. They include the total resummation of double-logarithmic contributions and accounting for the running QCD coupling effects.…

High Energy Physics - Phenomenology · Physics 2016-09-06 B. I. Ermolaev , M. Greco , S. I. Troyan

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 the massive flavor non-singlet Wilson coefficient for the heavy flavor contributions to the polarized structure function $g_1(x,Q^2)$ in the asymptotic region $Q^2 \gg m^2$ to 3-loop order in Quantum Chromodynamics at general…

High Energy Physics - Phenomenology · Physics 2015-06-17 A. Behring , J. Blümlein , A. De Freitas , A. von Manteuffel , C. Schneider

The explicit expressions for the non-singlet DIS structure functions obtained at small x by resumming the most singular logarithmic contributions are discussed and compared in detail with the DGLAP evolution for different values of x and…

High Energy Physics - Phenomenology · Physics 2010-03-25 B. I. Ermolaev , M. Greco , S. I. Troyan

The small $x$ behaviour of the structure function $h_1(x,Q^2)$ is studied within the leading logarithmic approximation of perturbative QCD. There are two contributions relevant at small $x$. The leading one behaves like $(\frac{1}{x})^0$…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. Kirschner , L. Mankiewicz , A. Schäfer , L. Szymanowski

We show that it is possible to use hard-Pomeron behavior to the gluon distribution and singlet structure function at low $x$. We derive a second-order independent differential equation for the gluon distribution and the singlet structure…

High Energy Physics - Phenomenology · Physics 2014-02-05 B. Rezaei , G. R. Boroun

A simple analytic expression for the non-singlet structure function $f_{NS}$ is given. The expression is derived from the result of Ref. [1] obtained by low $x$ resummation of the quark ladder diagrams in the double logarithmic…

High Energy Physics - Phenomenology · Physics 2009-11-10 Michael Lublinsky

Recent data on the structure function F_2(x,Q^2) at small values of x are analysed and compared with theoretical expectations. It is shown that the observed rise at small x is consistent with a logarithmic increase, growing logarithmically…

High Energy Physics - Phenomenology · Physics 2007-05-23 W. Buchmuller , D. Haidt

The small-$x$ contributions to the Bjorken sum rule within double logarithmic $ln^2x$ approximation for different input parametrisations $g_1^{NS}(x,Q_0^2)$ are presented. Analytical solutions of the evolution equations for full and…

High Energy Physics - Phenomenology · Physics 2007-05-23 Dorota Kotlorz , Andrzej Kotlorz

The numerical effects of the known all-order leading and next-to-leading logarithmic small-$x$ contributions to the anomalous dimensions and coefficient functions of the unpolarized singlet evolution are discussed for the structure…

High Energy Physics - Phenomenology · Physics 2009-10-30 J. Blümlein , A. Vogt

A generalization of the leading-order DGLAP evolution at small x is performed for the non-singlet structure function by resumming the leading-order DGLAP anomalous dimension to all orders in the QCD coupling. Explicit expressions are…

High Energy Physics - Phenomenology · Physics 2010-03-25 B. I. Ermolaev , M. Greco , S. I. Troyan

An alternative equation, resumming of the $\ln^2 1/x$ terms for the polarized nonsinglet structure function $g_1^{NS}$ at small $x$ is presented. Construction of the GLAP-like formula for the auxiliary function, corresponding to the…

High Energy Physics - Phenomenology · Physics 2011-03-17 Dorota Kotlorz , Andrzej Kotlorz

We calculate the one-loop twist-3 gluon contribution to the flavor-singlet structure function g_2(x,Q^2) in polarized deep-inelastic scattering and find that it is dominated by the contribution of the three-gluon operator with the lowest…

High Energy Physics - Phenomenology · Physics 2009-10-31 V. M. Braun , G. P. Korchemsky , A. N. Manashov

Total resummation of double- and single- logarithms of x contributing to the spin-dependent structure function g_1 ensures its steep rise at small $x$. In the asymptotic limit x ->0, the resummation leads to the Regge behavior of g_1 and…

High Energy Physics - Phenomenology · Physics 2007-05-23 B. I. Ermolaev , M. Greco , S. I. Troyan

Accounting for double-logarithms of x and running QCD coupling leads to expressions for both the non-singlet and singlet components of $g_1$. These expressions manifest the Regge asymptotics when x ->0 and differ considerably from the DGLAP…

High Energy Physics - Phenomenology · Physics 2007-05-23 B. I. Ermolaev , M. Greco , S. I. Troyan

The pure singlet asymptotic heavy flavor corrections to 3-loop order for the deep-inelastic scattering structure function $F_2(x,Q^2)$ and the corresponding transition matrix element $A_{Qq}^{(3), \sf PS}$ in the variable flavor number…

High Energy Physics - Phenomenology · Physics 2015-06-22 J. Ablinger , A. Behring , J. Blümlein , A. De Freitas , A. von Manteuffel , C. Schneider

The explicit expressions for the non-singlet DIS structure function g_1 at small $x$ are obtained by resumming the leading logarithmic contributions. The role played by the fits for the initial parton densities currently used in the DGLAP…

High Energy Physics - Phenomenology · Physics 2009-11-11 B. I. Ermolaev , M. Greco , S. I. Troyan

An approach which unifies the Double Logarithmic Approximation at small x and the leading order DGLAP evolution of fragmentation functions at large x is presented. This approach reproduces exactly the Modified Leading Logarithm…

High Energy Physics - Phenomenology · Physics 2015-06-25 S. Albino , B. A. Kniehl , G. Kramer , W. Ochs