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The typical transverse momentum $Q_s(t)$ (or "saturation" momentum) acquired by a hard particle propagating through a $\mathcal{N}=4$ SYM plasma increases over time like $t^\gamma$, with an anomalous exponent $\gamma>1/2$ characteristic of…

High Energy Physics - Phenomenology · Physics 2023-01-11 Paul Caucal

We present calculations of the structure functions F_2(x,Q^2) and F_L(x,Q^2), concentrating on small x. After discussing the standard expansion of the structure functions in powers of \alpha_s(Q^2) we consider a leading-order expansion in…

High Energy Physics - Phenomenology · Physics 2008-02-03 R. S. Thorne

We present a calculation of soft-gluon corrections in FCNC top-quark production via anomalous $t$-$q$-$g$ couplings. The soft anomalous dimension matrix is explicitly calculated at one-loop accuracy. This calculation allows threshold…

High Energy Physics - Phenomenology · Physics 2014-10-01 Nikolaos Kidonakis , Elwin Martin

It is widely believed that at small x, the BFKL resummed gluon splitting function should grow as a power of 1/x. But in several recent calculations it has been found to decrease for moderately small-x before eventually rising. We show that…

High Energy Physics - Phenomenology · Physics 2014-11-17 Marcello Ciafaloni , Dimitri Colferai , Gavin P. Salam , Anna M. Stasto

High energy hard scattering in large $N_{c}$ limit can be described by the QCD dipole model. In this paper, single, double and triple BFKL pomeron exchange amplitudes are computed explicitly within the dipole model. Based on the…

High Energy Physics - Phenomenology · Physics 2010-03-25 Bo-Wen Xiao

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 discuss the quantitative consequences of the resummation of the small-x contributions to the anomalous dimensions beyond next-to-leading order in alpha_s and up to next order in ln(1/x) (NLx) in a framework based on the renormalization…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Blümlein , V. Ravindran , W. L. van Neerven , A. Vogt

We show that in the case of the BFKL pomeron with running coupling the diffusion pattern is strongly modified and is characterised by the sudden tunneling transition to the non-perturbative regime. We suggest that by using the b - expansion…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. M. Stasto

We perform a global fit to the structure function F_2 measured in lepton-proton experiments at small values of Bjorken-x, x\le 0.01, for all experimentally available values of Q^2, 0.045 GeV^2\le Q^2 \le 800 GeV^2. We show that the recent…

High Energy Physics - Phenomenology · Physics 2009-09-01 J. L. Albacete , N. Armesto , J. G. Milhano , C. A. Salgado

We revisit the Next-to-Leading Order (two-loop) contributions to the Anomalous Dimensions of $\Delta F = 1$ four-quark operators in QCD. We devise a test for anomalous dimensions, that we regard as of general interest, and by means of which…

High Energy Physics - Phenomenology · Physics 2025-06-19 Pol Morell , Javier Virto

I discuss radiative corrections to the BFKL equation for high energy cross sections in perturbative QCD. Due to the gluon Reggeization in the next-to-leading $\ln s$ approximation, the form of the BFKL equation remains unchanged and the…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. S. Fadin

We obtain the quark and gluon rapidity anomalous dimension to fourth order in QCD. We calculate the N$^3$LO rapidity anomalous dimensions to higher order in the dimensional regulator and make use of the soft/rapidity anomalous dimension…

High Energy Physics - Phenomenology · Physics 2022-05-12 Claude Duhr , Bernhard Mistlberger , Gherardo Vita

A technique of large-charge expansion provides a novel opportunity for calculation of critical dimensions of operators $\phi^Q$ with fixed charge $Q$. In the small-coupling regime the polynomial structure of the anomalous dimensions can be…

High Energy Physics - Theory · Physics 2022-11-09 Alexander Bednyakov , Andrey Pikelner

We discuss the BFKL equation with a running gauge coupling and identify in its solutions the contributions originating from different transverse momentum scales. We show that for a running coupling constant the distribution of the gluons…

High Energy Physics - Phenomenology · Physics 2009-10-30 L. P. A. Haakman , O. K. Kancheli , J. H. Koch

Recent measurements for F_2(x,Q^2) have been analyzed in terms of the `dynamical' and `standard' parton model approach at NLO and NNLO of perturbative QCD. Having fixed the relevant NLO and NNLO parton distributions, the implications and…

High Energy Physics - Phenomenology · Physics 2015-05-13 Cristian Pisano

Non-perturbative corrections to hadronic observables represent a critical obstacle to increasing accuracy at colliders. Long taken to scale simply as $1/Q$, where $Q$ is the centre-of-mass scattering energy, recent work has opened the path…

High Energy Physics - Phenomenology · Physics 2025-07-28 Casey Farren-Colloty , Jack Helliwell , Rtvik Patel , Gavin P. Salam , Silvia Zanoli

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 present a calculation of the two-loop anomalous dimension for the transversity distribution h_1(x,Q^2), $\gamma^{h(1)}_n$, in the MS scheme of the dimensional regularization. Due to the chiral-odd nature, h_1 does not mix with the gluon…

High Energy Physics - Phenomenology · Physics 2016-08-25 A. Hayashigaki , Y. Kanazawa , Yuji Koike

We evaluate the complete four-loop anomalous dimension matrix that is necessary for determining the effective flavour-changing neutral current couplings qbar-q'-gamma and qbar-q'-g at the next-to-next-to-leading order in QCD. The resulting…

High Energy Physics - Phenomenology · Physics 2010-10-27 Michal Czakon , Ulrich Haisch , Mikolaj Misiak

I review recent results by Fadin,Lipatov and collaborators and by our group,leading to the almost complete calculation of the next-to-leading BFKL kernel,of its eigenvalues,and of the resummed gluon anomalous dimension. Qualitative…

High Energy Physics - Phenomenology · Physics 2007-05-23 Marcello Ciafaloni