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QCD factorization takes different forms in the large-x and small-x regimes. At large-x, collinear factorization leads to the DGLAP evolution equation, while at small-x, rapidity factorization results in the BFKL equation. To unify these…

High Energy Physics - Phenomenology · Physics 2024-07-22 Swagato Mukherjee , Vladimir Skokov , Andrey Tarasov , Shaswat Tiwari

Using methods of effective field theory, a systematic analysis of the fragmentation functions D_{a/H}(x,m_Q) of a hadron H containing a heavy quark Q is performed (with a=Q,Q_bar,q,q_bar,g). By integrating out pair production of virtual and…

High Energy Physics - Phenomenology · Physics 2007-06-15 Matthias Neubert

Quantum electrodynamics and electroweak corrections are important ingredients for many theoretical predictions at the LHC. This paper documents APFEL, a new PDF evolution package that allows for the first time to perform DGLAP evolution up…

High Energy Physics - Phenomenology · Physics 2015-06-17 Valerio Bertone , Stefano Carrazza , Juan Rojo

We present a new method for solving the BFKL evolution applicable at both leading and next-to-leading logarithmic accuracy, and tailored to the study of QCD multi-jet events at colliders. We utilise this to discuss corrections to the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Jeppe R. Andersen

We study the time evolution of the density matrix of a high energy quark in the presence of a dense QCD background that is modeled as a stochastic Gaussian color field. At late times, we find that only the color singlet component of the…

High Energy Physics - Phenomenology · Physics 2023-12-19 João Barata , Jean-Paul Blaizot , Yacine Mehtar-Tani

QCD, the theory of the strong interactions, involves quarks interacting with non-Abelian gluon fields. This theory has many features that are difficult to impossible to see in conventional diagrammatic perturbation theory. This includes…

High Energy Physics - Phenomenology · Physics 2021-09-01 Michael Creutz

A pedagogical introduction to the heavy quark theory is given. It is explained that various expansions in the inverse heavy quark mass $1/m_Q$ present a version of the Wilson operator product expansion in QCD. A systematic approach is…

High Energy Physics - Phenomenology · Physics 2009-09-25 M. Shifman

We present and discuss the release of novel sets of collinear, variable-flavor-number-scheme fragmentation functions for axial-vector, fully heavy $T_{4c}(1^{+-})$ and $T_{4b}(1^{+-})$ tetraquarks. Working within the single-parton…

High Energy Physics - Phenomenology · Physics 2025-06-04 Francesco Giovanni Celiberto

The DGLAP, BFKL, modified DGLAP and modified BFKL equations are constructed in a unified partonic framework. The antishadowing effect in the recombination process is emphasized, which leads to two different small $x$ behaviors of gluon…

High Energy Physics - Phenomenology · Physics 2007-05-23 Wei Zhu , Zhenqi Shen , Jifeng Yang , Jianhong Ruan

We study the transverse momentum dependent (TMD) evolution of the Collins azimuthal asymmetries in $e^+e^-$ annihilations and semi-inclusive hadron production in deep inelastic scattering (SIDIS) processes. All the relevant coefficients are…

High Energy Physics - Phenomenology · Physics 2016-01-20 Zhong-Bo Kang , Alexei Prokudin , Peng Sun , Feng Yuan

The dynamics of high partonic density QCD is presented considering, in the double logarithm approximation, the parton recombination mechanism built in the AGL formalism, developed including unitarity corrections for the nucleon as well for…

High Energy Physics - Phenomenology · Physics 2014-11-17 M. B. Gay Ducati

We discuss the interplay of low-x physics and QCD scaling violations by extending the unified approach describing inclusive structure functions and diffractive production in $\gamma* p$ interactions proposed in previous papers, to large…

High Energy Physics - Phenomenology · Physics 2013-05-29 Nestor Armesto , Alexei B. Kaidalov , Carlos A. Salgado , Konrad Tywoniuk

The dynamics of expansion of the Universe and evolution of scalar perturbations are studied for the quintessential scalar fields $Q$ with the classical Lagrangian satisfying the additional condition $w=const$ or $c^2_a=0$. Both…

Astrophysics · Physics 2009-08-10 B. Novosyadlyj , O. Sergijenko

Transport equations have been applied successfully to describe the quarkonium evolution inside the quark-gluon plasma, which include both plasma screening effects and recombination. We demonstrate how the quarkonium transport equation is…

High Energy Physics - Phenomenology · Physics 2020-09-03 Xiaojun Yao , Weiyao Ke , Yingru Xu , Steffen Bass , Thomas Mehen , Berndt Müller

A set of coupled kinetic equations describing in the Abelian approximation a mixture of quarks and self-interacting gluons is formulated and solved numerically. The model includes the Schwinger-like mechanism for particle creation in a…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. V. Skokov , S. A. Smolyansky , V. D. Toneev

Complex Langevin simulations provide an alternative to sample path integrals with complex weights and therefore are suited to determine the phase diagram of QCD from first principles. Adaptive step-size scaling and gauge cooling are used to…

High Energy Physics - Lattice · Physics 2015-11-02 Gert Aarts , Felipe Attanasio , Benjamin Jäger , Erhard Seiler , Dénes Sexty , Ion-Olimpiu Stamatescu

These lectures discuss aspects of high energy evolution in QCD. This includes the derivation of the JIMWLK equation, basic physics of its solutions and recent work on inclusion of Pomeron loops. The entire discussion is given in the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Alex Kovner

We present a QCD based interpretation of heavy quark fragmentation which utilizes the heavy quark mass expansion. By distinguishing between perturbative and non-perturbative QCD effects, we show how to reliably extract mass independent…

High Energy Physics - Phenomenology · Physics 2009-09-15 R. L. Jaffe , L. Randall

A quantum-kinetic formulation of the dynamical evolution of a high-energy non-equilibrium gluon system at finite density is developed, to study the interplay between quantum fluctuations of high-momentum (hard) gluons and the low-momentum…

High Energy Physics - Phenomenology · Physics 2008-11-26 Klaus Geiger

Stochastic processes described by evolution equations in the universality class of the FKPP equation may be approximately factorized into a linear stochastic part and a nonlinear deterministic part. We prove this factorization on a model…

High Energy Physics - Phenomenology · Physics 2008-11-26 S. Munier