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We present the next-to-next-to-next-to-leading order (N^3LO) contributions to the non-singlet splitting functions for both parton distribution and fragmentation functions in perturbative QCD. The exact expressions are derived for the terms…

High Energy Physics - Phenomenology · Physics 2017-10-25 S. Moch , B. Ruijl , T. Ueda , J. A. M. Vermaseren , A. Vogt

We compute the polarized splitting functions in the triple collinear limit at next-to-leading order accuracy (NLO) in the strong coupling $\alpha_{\rm S}$, for the splitting processes $\gamma \to q \bar{q} \gamma$, $\gamma \to q \bar{q} g$…

High Energy Physics - Phenomenology · Physics 2015-03-12 German F. R. Sborlini , Daniel de Florian , German Rodrigo

We study the next-to-next-to-leading order (NNLO) evolution of flavour non-singlet quark densities and structure functions in massless perturbative QCD. Present information on the corresponding three-loop splitting functions is used to…

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

We present the results of our QCD analysis for non-singlet unpolarized quark distributions and structure function $F_2(x,Q^2)$ up to N$^3$LO. In this regards 4-loop anomalous dimension can be obtain from the Pad\'e approximations. The…

High Energy Physics - Phenomenology · Physics 2010-02-03 Ali N. Khorramian , H. Khanpour , S. Atashbar Tehrani

We present a next-to-next-to-leading order (NNLO) global QCD analysis of the proton's helicity parton distribution functions (PDFs), the first of its kind. To obtain the distributions, we use data for longitudinal spin asymmetries in…

High Energy Physics - Phenomenology · Physics 2025-03-31 Ignacio Borsa , Daniel de Florian , Rodolfo Sassot , Marco Stratmann , Werner Vogelsang

We have calculated the splitting functions governing the evolution of the unpolarized parton distributions of the photon at the next-to-next-to-leading order (NNLO) of massless perturbative QCD. The results, presented here mainly in terms…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Vogt , S. Moch , J. Vermaseren

We compute the three-loop corrections to the helicity amplitudes for $q\bar{q}\to Q\bar{Q}$ scattering in massless QCD. In the Lorentz decomposition of the scattering amplitude we avoid evanescent Lorentz structures and map the…

High Energy Physics - Phenomenology · Physics 2024-11-06 Fabrizio Caola , Amlan Chakraborty , Giulio Gambuti , Andreas von Manteuffel , Lorenzo Tancredi

We calculate the unpolarized and polarized three--loop anomalous dimensions and splitting functions $P_{\rm NS}^+, P_{\rm NS}^-$ and $P_{\rm NS}^{\rm s}$ in QCD in the $\overline{\sf MS}$ scheme by using the traditional method of…

High Energy Physics - Phenomenology · Physics 2021-09-15 J. Blümlein , P. Marquard , C. Schneider , K. Schönwald

We study the factorisation properties of one-loop scattering amplitudes in the triple collinear limit and extract the universal splitting amplitudes for processes initiated by a gluon. The splitting amplitudes are derived from the analytic…

High Energy Physics - Phenomenology · Physics 2015-07-20 Simon Badger , Francesco Buciuni , Tiziano Peraro

We have studied the recently completed analytic all-N expressions for the four-loop anomalous dimensions corresponding to the next-to-next-to-next-to-leading order splitting functions for the non-singlet quark distribution in perturbative…

High Energy Physics - Phenomenology · Physics 2026-05-06 S. Moch , A. Vogt

We compute the three-loop helicity amplitudes for $q\bar{q} \to gg$ and its crossed partonic channels, in massless QCD. Our analytical results provide a non-trivial check of the color quadrupole contribution to the infrared poles for…

High Energy Physics - Phenomenology · Physics 2023-01-04 Fabrizio Caola , Amlan Chakraborty , Giulio Gambuti , Andreas von Manteuffel , Lorenzo Tancredi

We review the nucleon's twist-3 polarized structure functions from the viewpoint of gauge invariant, nonlocal light-cone operators in QCD. We discuss a systematic treatment of the polarized structure functions and the corresponding parton…

High Energy Physics - Phenomenology · Physics 2009-10-31 Jiro Kodaira , Kazuhiro Tanaka

We present recent advancements in the computation of three-loop four-particle helicity amplitudes in full-color massless QCD. In this contribution, we focus on the $gg \to \gamma\gamma$ process. We show how to obtain compact analytic…

High Energy Physics - Phenomenology · Physics 2024-10-04 Piotr Bargiela

We report on recent progress on the splitting functions for the evolution of parton distributions and related quantities, the (lightlike) cusp anomalous dimensions, in perturbative QCD. New results are presented for the four-loop…

High Energy Physics - Phenomenology · Physics 2018-08-29 A. Vogt , F. Herzog , S. Moch , B. Ruijl , T. Ueda , J. A. M. Vermaseren

We compute the full three-loop coefficient functions for the structure functions F_2 and F_L in massless perturbative QCD. The results for F_L complete the next-to-next-to-leading order description of unpolarized electromagnetic…

High Energy Physics - Phenomenology · Physics 2008-11-26 J. A. M. Vermaseren , A. Vogt , S. Moch

We determine the two-loop 'time-like' Altarelli-Parisi splitting functions, appearing in the next-to-leading order Q^2-evolution equations for fragmentation functions, via analytic continuation of the corresponding 'space-like' splitting…

High Energy Physics - Phenomenology · Physics 2014-11-17 M. Stratmann , W. Vogelsang

We present the results of our QCD analysis for polarized quark distribution and structure function $xg_1 (x,Q^2)$. We use very recently experimental data to parameterize our model. New parameterizations are derived for the quark and gluon…

High Energy Physics - Phenomenology · Physics 2009-04-22 S. Atashbar Tehrani , Ali N. Khorramian

We report a complete computation of next-to-next-to-leading order (NNLO) helicity and transversity Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) splitting functions, in both space-like and time-like kinematics. These results are…

High Energy Physics - Phenomenology · Physics 2026-03-31 Yu Jiao Zhu

Perturbative solutions for unpolarized QED parton distribution and fragmentation functions are presented explicitly in the next-to-leading logarithmic approximation. The scheme of iterative solution of QED evolution equations is described…

High Energy Physics - Phenomenology · Physics 2023-09-06 A. B. Arbuzov , U. E. Voznaya

We study the next-to-next-to-leading order (NNLO) evolution of flavour singlet parton densities and structure functions in massless perturbative QCD. Present information on the corresponding three-loop splitting functions is used to derive…

High Energy Physics - Phenomenology · Physics 2009-10-31 W. L. van Neerven , A. Vogt