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We study the splitting functions for the evolution of fragmentation distributions and the coefficient functions for single-hadron production in semi-inclusive electron-positron annihilation in massless perturbative QCD for small values of…

High Energy Physics - Phenomenology · Physics 2015-06-05 C. -H. Kom , A. Vogt , K. Yeats

A NNLO analysis of certain logarithmic expansions, developed for precision studies of the evolution of the QCD parton distributions (pdf) at the Large Hadron Collider, is presented. We elaborate on their relations to all the solutions of…

High Energy Physics - Phenomenology · Physics 2010-03-25 Alessandro Cafarella , Claudio Coriano' , Marco Guzzi

We start from the two existing QCD evolution equations for structure functions, the BFKL and DGLAP equations, and discuss the theoretical hints for a unifying picture of the evolution in $x$ and $Q^2.$ The main difficulty is due to the…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. Peschanski

We numerically analyse the evolution of the flavor non-singlet $g_{1}$ structure function taking into account the all-order resummation of $\alpha_{s} ln^{2}x$ terms which is expected to have much stronger effects than the DGLAP evolution…

High Energy Physics - Phenomenology · Physics 2007-05-23 Yuichiro Kiyo , Jiro Kodaira , Hiroshi Tochimura

We show that a unified approach to the perturbative evolution of structure functions which sums all logarithms of Q^2 and 1/x at leading and next-to-leading order yields results in full agreement with the 1993 HERA data for F_2. This makes…

High Energy Physics - Phenomenology · Physics 2007-05-23 R. D. Ball , S. Forte

Using repeated Laplace transform, We find an analytical solution for DGLAP evolution equations for extracting the pion, kaon and proton Fragmentation Functions (FFs) at NLO approximation. We also study the symmetry breaking of the sea…

High Energy Physics - Phenomenology · Physics 2025-12-12 M. Zareei , F. Taghavi-Shahri , S. Atashbar Tehrani , M. Sarbishei

We consider the higher-order resummation of Sudakov double logarithms in the presence of multiple coupled gauge interactions. The associated evolution equations depend on the coupled $\beta$ functions of two (or more) coupling constants…

High Energy Physics - Phenomenology · Physics 2020-04-22 Georgios Billis , Frank J. Tackmann , Jim Talbert

We consider the computation of D and B fragmentation functions in e+e- annihilation. We compare the results of fitting present data using the next-to-leading-logarithmic resummed approach, versus the O(alpha_s^2) fixed-order calculation,…

High Energy Physics - Phenomenology · Physics 2009-10-31 P. Nason , C. Oleari

We summarize our recent result for a splitting function for small x evolution which includes resummed small x logarithms deduced from the leading order BFKL equation with the inclusion of running coupling effects. We compare this improved…

High Energy Physics - Phenomenology · Physics 2007-05-23 Guido Altarelli , Richard D. Ball , Stefano Forte

We formulate and numerically solve the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi~(DGLAP) evolution equations at next-to-leading order in perturbation theory directly for a basis of 6 physical, observable structure functions in deeply…

High Energy Physics - Phenomenology · Physics 2025-09-03 Tuomas Lappi , Heikki Mäntysaari , Hannu Paukkunen , Mirja Tevio

We are investigating the behavior of the fragmentation function of a gluon, denoted as $ D_{g}(x,\mu^2)$, where $\mu$ represents the observable scale. This function is derived from the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP)…

High Energy Physics - Phenomenology · Physics 2025-09-25 H. S. Nakhaei , G. R. Boroun

We have derived the coefficients of the highest three 1/x-enhanced small-x logarithms of all timelike splitting functions and the coefficient functions for the transverse fragmentation function in one-particle inclusive e^+e^- annihilation…

High Energy Physics - Phenomenology · Physics 2015-05-30 A. Vogt

New methods of solutions of the DGLAP equation and their implementation through NNLO in QCD are briefly reviewed. We organize the perturbative expansion that describes in $x$-space the evolved parton distributions in terms of scale…

High Energy Physics - Phenomenology · Physics 2008-12-30 Alessandro Cafarella , Claudio Coriano , Marco Guzzi

We present particular and unique solutions of Dokshitzer- Gribov- Lipatov- Altarelli-Parisi (DGLAP) evolution equation for gluon structure function in leading order (LO) and obtain t and x-evolutions of gluon structure function at small-x.…

High Energy Physics - Phenomenology · Physics 2012-09-20 R. Rajkhowa , J. K. Sarma

We show how perturbation theory may be reorganized to give splitting functions which include order by order convergent sums of all leading logarithms of $x$. This gives a leading twist evolution equation for parton distributions which sums…

High Energy Physics - Phenomenology · Physics 2014-11-17 R. D. Ball , S. Forte

We compute the perturbative component of the fragmentation function of the $b$ quark to the best of the present theoretical knowledge. The fixed-order calculation to order $\alpha_s^2$ of the fragmentation function at the initial scale is…

High Energy Physics - Phenomenology · Physics 2022-10-13 Fabio Maltoni , Giovanni Ridolfi , Maria Ubiali , Marco Zaro

We have investigated the next-to-next-to-leading order (NNLO) corrections to inclusive hadron production in e^+e^- annihilation and the related parton fragmentation distributions, the `time-like' counterparts of the `space-like'…

High Energy Physics - Phenomenology · Physics 2008-11-26 A. Mitov , S. Moch , A. Vogt

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

Explicit expressions for the non-singlet and singlet structure functions g_1 in the small-x region are obtained. They include the total resummation of the double- and single- logarithms of x and account for the running QCD coupling effects.…

High Energy Physics - Phenomenology · Physics 2016-12-07 B. I. Ermolaev , M. Greco , S. I. Troyan

We present a comprehensive study of high-energy double logarithms in inclusive DIS. They appear parametrically as alpha_s^n ln^{2n-k} x at the n-th order in perturbation theory in the splitting functions for the parton evolution and the…

High Energy Physics - Phenomenology · Physics 2022-09-07 J. Davies , C. -H. Kom , S. Moch , A. Vogt