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The twist three contributions to the $Q^2$-evolution of the spin-dependent structure function $g_2(x_{Bj},Q^2)$ are considered in the non-local operator product approach. Defining appropriate twist three distribution function we derive…

High Energy Physics - Phenomenology · Physics 2007-05-23 B. Geyer , D. Müller , D. Robaschik

It is well-known that direct analytic continuation of DGLAP evolution kernel (splitting functions) from space-like to time-like kinematics breaks down at three loops. We identify the origin of this breakdown as splitting functions are not…

High Energy Physics - Phenomenology · Physics 2021-02-24 Hao Chen , Tong-Zhi Yang , Hua Xing Zhu , Yu Jiao Zhu

We analyse the available data on the polarized asymmetries $A_1$ for proton, neutron and deuteron targets. We use a homogeneous and updated set of unpolarized structure functions to derive $g_1$ from $A_1$, and we accurately correct for the…

High Energy Physics - Phenomenology · Physics 2009-10-22 G. Altarelli , P. Nason , G. Ridolfi

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

We report on progress in the calculation of 3-loop corrections to the deep-inelastic structure functions from massive quarks in the asymptotic region of large momentum transfer $Q^2$. Recently completed results allow us to obtain the…

In this work we have suggested a solution of the Gribov-Levin-Ryskin-Mueller-Qiu (GLR-MQ) nonlinear evolution equation at next-to-next-to-leading order (NNLO). The range of $Q^2$ in which we have solved the GLR-MQ equation is Regge region…

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

According to a rederivation - due to Collins and Qiu - the DGLAP equation can be reinterpreted (in leading order) in a probabilistic way. This form of the equation has been used indirectly to prove the bound $|\Delta f(x,Q)| < f(x,Q)$…

High Energy Physics - Phenomenology · Physics 2014-11-17 Alessandro Cafarella , Claudio Corianó

We extract polarized parton distribution functions (PPDFs), referred to as "KTA17," together with the highly correlated strong coupling $\alpha_s$ from recent and up-to-date $g_1$ and $g_2$ polarized structure functions world data at…

High Energy Physics - Phenomenology · Physics 2017-04-07 Hamzeh Khanpour , Sara Taheri Monfared , S. Atashbar Tehrani

We present a new QCD evolution library for unpolarized parton distribution functions: EKO. The program solves DGLAP equations up to next-to-next-to-leading order. The unique feature of EKO is the computation of solution operators, which are…

High Energy Physics - Phenomenology · Physics 2022-11-15 Alessandro Candido , Felix Hekhorn , Giacomo Magni

We constructed two sets of twist-3 correlation functions that are responsible for generating the novel single transverse-spin asymmetry in the QCD collinear factorization approach. We derive evolution equations for these universal…

High Energy Physics - Phenomenology · Physics 2009-02-26 Zhong-Bo Kang , Jian-Wei Qiu

We study the impact of the QCD DGLAP evolution on the geometric scaling of the gluon distributions which is expected to hold at small x within the saturation models. To this aim we solve the DGLAP evolution equations with the initial…

High Energy Physics - Phenomenology · Physics 2014-11-17 J. Kwiecinski , A. M. Stasto

In this paper t and x-evolutions of gluon distribution function from Dokshitzer-Gribov-Lipatov-Altarelli-Parisi(DGLAP) evolution equation in leading order(LO) at low-x, assuming the Regge behaviour of quark and gluon at this limit, are…

High Energy Physics - Phenomenology · Physics 2014-11-18 U. Jamil , J. K. Sarma

A numerical method is developed to solve the time-dependent Dirac equation in cylindrical coordinates for 3-D axisymmetric systems. The time evolution is treated by a splitting scheme in coordinate space using alternate direction iteration,…

Computational Physics · Physics 2015-04-03 François Fillion-Gourdeau , Emmanuel Lorin , André D. Bandrauk

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

A QCD analysis of the world data on polarized deep inelastic scattering is presented in next--to--leading order, including the heavy flavor Wilson coefficient in leading order in the fixed flavor number scheme. New parameterizations are…

High Energy Physics - Phenomenology · Physics 2014-11-21 Johannes Blümlein , Helmut Böttcher

We analize the use of algorithms based in x-space for the solution of renormalization group equations of DGLAP-type and test their consistency by studying bounds among partons distributions - in our specific case Soffer's inequality and the…

High Energy Physics - Phenomenology · Physics 2014-11-17 Alessandro Cafarella , Claudio Coriano' , Marco Guzzi

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

We discuss the application of an analytic approach called the analytic perturbation theory (APT) to the QCD analysis of DIS data. In particular, the results of the QCD analysis of a set of `fake' data on the polarized nonsinglet Delta{q3}…

High Energy Physics - Phenomenology · Physics 2015-01-16 A. V. Sidorov , O. P. Solovtsova

We solve numerically the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations for the evolution of fragmentation functions using the Laguerre method. We extend this method to include supersymmetric evolution. The solution to the…

High Energy Physics - Phenomenology · Physics 2014-11-17 Ramon Toldra

We analyze the general nonlinear evolution equations for multi gluon correlators derived in hep-ph/9709432 by restricting ourselves to a double logarithmic region. In this region our evolution equation becomes local in transverse momentum…

High Energy Physics - Phenomenology · Physics 2014-11-17 Jamal Jalilian-Marian , Alex Kovner , Andrei Leonidov , Heribert Weigert