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The coefficients of the generating function $(q;q)^\alpha_\infty$ produce $p_\alpha(n)$ for $\alpha \in \mathbb{Q}$. In particular, when $\alpha = -1$, the partition function is obtained. Recently, Chan and Wang identified and proved…

Number Theory · Mathematics 2021-03-16 Yunseo Choi

We summarize recent results on the evolution of unpolarized parton densities and deep-inelastic structure functions in massless perturbative QCD. Due to last year's extension of the integer-moment calculations of the three-loop splitting…

High Energy Physics - Phenomenology · Physics 2008-11-26 W. L. van Neerven , A. Vogt

We extend the results of Lappi {\em et al.}, Eur.~Phys.~J.~C {\bf 84}, 84 (2024), to show that it is possible to obtain expressions for the longitudinal, singlet and gluon structure functions $F_L$, $F_S$ and $G$ in deep inelastic…

High Energy Physics - Phenomenology · Physics 2026-05-12 G. R. Boroun , Loyal Durand , Phuoc Ha

Using Laplace transform techniques, along with newly-developed accurate numerical inverse Laplace transform algorithms, we decouple the solutions for the singlet structure function $F_s(x,Q^2)$ and $G(x,Q^2)$ of the two leading-order…

High Energy Physics - Phenomenology · Physics 2010-04-12 Martin M. Block , Loyal Durand , Phuoc Ha , Douglas W. McKay

The gluon fragmentation function of $g \to h_c$ at leading order of strong coupling constant $\alpha_s$ and typical velocity $v$ is calculated in the framework of NRQCD, of which the contributions from both color-singlet and -octet…

High Energy Physics - Phenomenology · Physics 2009-12-01 Gang Hao , YaBing Zuo , Cong-Feng Qiao

We present the perturbative parts of the structure functions F_2^c and F_L^c for a gluon target having nonzero transverse momentum squared at order \alpha _s. The results of the double convolution (with respect to the Bjorken variable x and…

High Energy Physics - Phenomenology · Physics 2017-08-23 A. V. Kotikov , A. V. Lipatov , G. Parente , N. P. Zotov

I use a direct method to extract the longitudinal structure function in the next-to-leading order approximation with respect to the number of active flavor from the parametrization of parton distributions. The contribution of charm and…

High Energy Physics - Phenomenology · Physics 2021-10-12 G. R. Boroun

We present the order $\alpha_s^2$ contributions to the coefficient functions corresponding to the longitudinal fragmentation function $F_L(x,Q^2)$. A comparison with the leading order $\alpha_s$ result for $F_L(x,Q^2)$ shows that the…

High Energy Physics - Phenomenology · Physics 2009-10-28 P. J. Rijken , W. L. van Neerven

Power-suppressed corrections to parton evolution may affect the theoretical accuracy of current determinations of parton distributions. We study the role of multigluon-exchange terms in the extraction of the gluon distribution for the Large…

High Energy Physics - Phenomenology · Physics 2008-11-26 F. Hautmann

The twist--2 heavy flavor contributions to the polarized structure function $g_2(x,Q^2)$ are calculated. We show that this part of $g_2(x,Q^2)$ is related to the heavy flavor contribution to $g_1(x,Q^2)$ by the Wandzura--Wilczek relation to…

High Energy Physics - Phenomenology · Physics 2016-09-06 J. Blümlein , V. Ravindran , W. L. van Neerven

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

In this paper we introduce the notions of (p,q)-th relative Gol'dberg order and (p,q)-th relative Gol'dberg type of entire functions of several complex variables where p,q are any positive integers. Then we study some growth properties of…

Complex Variables · Mathematics 2018-02-21 Tanmay Biswas

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 2011-04-11 S. Albino , B. A. Kniehl , G. Kramer , W. Ochs

This talks examines the effect of angular ordering on the small-x evolution of the unintegrated gluon distribution, and discusses the characteristic function for the CCFM equation.

High Energy Physics - Phenomenology · Physics 2016-11-03 M. Scorletti

We present the calculation of the two-loop spin splitting functions $P_{ij}^{(1)}(x)\; (i,j = q,g)$ contributing to the next-to-leading order corrected spin structure function $g_1(x,Q^2)$. These splitting functions, which are presented in…

High Energy Physics - Phenomenology · Physics 2018-05-18 R. Mertig , W. L. van Neerven

We present new sets of fragmentation functions for charged pions, charged kaons, and protons, both at the leading and next-to-leading orders. They are fitted to the scaled-momentum distributions of these hadrons measured in e+e-…

High Energy Physics - Phenomenology · Physics 2008-11-26 B. A. Kniehl , G. Kramer , B. Pötter

We revisit the basic steps necessary to obtain next-to-leading-logarithmic accurate small-$x$ results for the DGLAP splitting functions, and their implementations within the HELL framework. We derive new analytical all-order results for the…

High Energy Physics - Phenomenology · Physics 2026-03-04 Marco Bonvini , Stefano Frixione , Giovanni Stagnitto

The contribution of quarks with masses m >> Lambda_QCD is the only part of the structure functions in deep-inelastic scattering (DIS) which is not yet known at the next-to-next-to-leading order (NNLO) of perturbative QCD. We present…

High Energy Physics - Phenomenology · Physics 2016-08-09 H. Kawamura , N. A. Lo Presti , S. Moch , A. Vogt

We perform a full next-to-leading analysis of the the available experimental data on the polarized structure function g_1 of the nucleon, and give a precise determination of its singlet axial charge together with a thorough assessment of…

High Energy Physics - Phenomenology · Physics 2009-10-28 R. D. Ball , S. Forte , G. Ridolfi

We calculate the transverse momentum dependent gluon-to-gluon splitting function within $k_T$-factorization, generalizing the framework employed in the calculation of the quark splitting functions in [1-3] and demonstrate at the same time…

High Energy Physics - Phenomenology · Physics 2018-03-07 M. Hentschinski , A. Kusina , K. Kutak , M. Serino