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Related papers: Spin-Dependent Antenna Splitting Functions

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We develop the notion of shower partons and determine their distributions in jets in the framework of the recombination model. The shower parton distributions obtained render a good fit of the fragmentation functions. We then illustrate the…

High Energy Physics - Phenomenology · Physics 2011-02-01 Rudolph C. Hwa , C. B. Yang

The implementation of a new final-state parton-shower algorithm in the Pythia event generator is described. The shower algorithm, dubbed Apollo, combines central aspects of the Vincia antenna shower with the global transverse-recoil scheme…

High Energy Physics - Phenomenology · Physics 2024-06-27 Christian T Preuss

We present the next-to-next-to-leading order (NNLO) contributions to the main splitting functions for the evolution of longitudinally polarized parton densities of hadrons in perturbative QCD. The quark-quark and gluon-quark splitting…

High Energy Physics - Phenomenology · Physics 2015-06-22 S. Moch , J. A. M. Vermaseren , A. Vogt

Structure functions of the spin-1 deuteron will be investigated experimentally from the late 2020's at various facilities such as Thomas Jefferson National Accelerator Facility, Fermi National Accelerator Laboratory, nuclotron-based ion…

High Energy Physics - Phenomenology · Physics 2025-11-04 S. Kumano

The second-order QCD matrix elements give a very good agreement with experimental data on the angular distributions of the four-jet events in e+e- collisions at the Z0 resonance energy. Unfortunately the description of the sub-jet structure…

High Energy Physics - Phenomenology · Physics 2007-05-23 Johan André

We introduce a method for the separation of soft and collinear logarithms in QCD parton evolution at $\mathcal{O}(\alpha_s^2)$ and at leading color. Using an implementation of the technique in the Dire parton shower, we analyze the…

High Energy Physics - Phenomenology · Physics 2022-06-29 Leif Gellersen , Stefan Höche , Stefan Prestel

The theoretical description of photon production at particle colliders combines direct photon radiation and fragmentation processes, which can not be separated from each other for definitions of photon isolation used in experimental…

High Energy Physics - Phenomenology · Physics 2022-05-06 Thomas Gehrmann , Robin Schürmann

We present a new formalism for parton shower simulation of QCD jets, which incorporates the following features: invariance under boosts along jet axes, improved treatment of heavy quark fragmentation, angular-ordered evolution with soft…

High Energy Physics - Phenomenology · Physics 2014-11-17 Stefan Gieseke , Philip Stephens , Bryan Webber

A framework to include triple collinear splitting functions into parton showers is presented, and the implementation of flavor-changing NLO splitting kernels is discussed as a first application. The correspondence between the Monte-Carlo…

High Energy Physics - Phenomenology · Physics 2017-11-01 Stefan Höche , Stefan Prestel

The evolution of shower parton distributions in a jet is investigated in the framework of quark recombination model. The distributions are parameterized and the $Q^2$ dependence of the parameters is given by polynomials of $\ln Q^2$ for a…

Nuclear Theory · Physics 2009-11-11 Z. G. Tan , C. B. Yang

Transverse-momentum dependent parton distributions can be introduced gauge-invariantly in QCD from high-energy factorization. We discuss Monte Carlo applications of these distributions to parton showers and jet physics, with a view to the…

High Energy Physics - Phenomenology · Physics 2009-02-18 F. Hautmann , H. Jung

We propose a method for combining QCD matrix elements and parton showers in Monte Carlo simulations of hadronic final states in $e^+e^-$ annihilation. The matrix element and parton shower domains are separated at some value $y_{ini}$ of the…

High Energy Physics - Phenomenology · Physics 2010-02-03 S. Catani , F. Krauss , R. Kuhn , B. R. Webber

This article gives an introduction to transverse momentum dependent (TMD) parton distribution functions and their use in shower Monte Carlo event generators for high-energy hadron collisions, and describes recent progress in the treatment…

High Energy Physics - Phenomenology · Physics 2012-05-30 F. Hautmann , M. Hentschinski , H. Jung

Helicity-dependent generalized parton distributions of the nucleon are derived from the overlap representation of generalized parton distributions using light-cone wave functions obtained in constituent quark models. Results from two…

High Energy Physics - Phenomenology · Physics 2009-11-10 S. Boffi , B. Pasquini , M. Traini

We define a number of quark fragmentation functions for spin-0, -1/2 and -1 hadrons, and classify them according to their twist, spin and chirality. As an example of their applications, we use them to analyze semi-inclusive deep-inelastic…

High Energy Physics - Phenomenology · Physics 2009-10-22 Xiangdong Ji

We calculate the functions of parton fragmentation into $^3P_J$ quarkonium at order $\alpha_s ^2$, where the parton can be a heavy or light quark. The obtained functions explicitly satisfy the Altarelli-Parisi equation and they are…

High Energy Physics - Phenomenology · Physics 2010-11-01 J. P. Ma

This article is an introduction to parton distribution functions and their generalizations which describe the quark and gluon structure of hadrons, and can be measured in various high-energy scattering processes. We provide the theoretical…

High Energy Physics - Phenomenology · Physics 2026-01-23 Cédric Lorcé , A. Metz , B. Pasquini , P. Schweitzer

Parton showers lie at the core of Shower Monte Carlo event generators, the default theoretical tools used to interpret collider data. In these proceedings, we summarise the strategy of the PanScales collaboration that led to the attainment…

High Energy Physics - Phenomenology · Physics 2025-05-20 Silvia Ferrario Ravasio

In the Framework of {\it{valon model}} we have calculated the parton distribution in a valon for both the polarized and unpolarized cases. These distributions are originated purely from the dressing of a valence quark in QCD and are common…

High Energy Physics - Phenomenology · Physics 2007-05-23 Firooz Arash , Fatemeh Taghavi

Off-shell, transverse-momentum dependent splitting functions can be defined from the high-energy limit of partonic decay amplitudes. Based on these splitting functions, we construct Sudakov form factors and formulate a new parton branching…

High Energy Physics - Phenomenology · Physics 2022-07-27 F. Hautmann , M. Hentschinski , L. Keersmaekers , A. Kusina , K. Kutak , A. Lelek