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Parton
About: Parton is a research topic. Over the lifetime, 13484 publications have been published within this topic receiving 368877 citations.
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TL;DR: In this article, a strongly interacting particle is a finite region of space to which fields are confined, and the confinement is accomplished in a Lorentz-invariant way by endowing the finite region with a constant energy per unit volume, $B$.
Abstract: We propose that a strongly interacting particle is a finite region of space to which fields are confined. The confinement is accomplished in a Lorentz-invariant way by endowing the finite region with a constant energy per unit volume, $B$. We call this finite region a "bag." The contained fields may be either fermions or bosons and may have any spin; they may or may not be coupled to one another. Equations of motion and boundary conditions are obtained from a variational principle. The confining region has no dynamical freedom but constrains the fields inside: There are no excitations of the coordinates determining the confining region. The model possesses many desirable features of hadron dynamics: (i) a parton interpretation and presumably Bjorken scaling; the confined fields are free or weakly interacting except close to the boundary; (ii) infinitely rising Regge trajectories as a consequence of the bag's finite extent; (iii) the Hagedorn degeneracy or limiting temperature; (iv) all physical hadrons are singlets under hadronic gauge symmetries. For example, in a theory of fractionally charged, "colored" quarks interacting with colored, massless gauge vector gluons, if both quark and gluon fields are confined to the bag, only color-singlet solutions exist. In addition to establishing these general properties, we present complete classical and quantum solutions for free scalars and also for free fermions inside a bag of one space and one time dimension. Both systems have linear mass-squared spectra. We demonstrate Poincar\'e invariance at the classical level in any dimension and at the quantum level for the above-mentioned explicit solutions in two dimensions. We discuss the behavior of specific solutions in one and three space dimensions. We also discuss in detail the problem of fermion boundary conditions, which follow only indirectly from the variational principle.
1,888 citations
TL;DR: Herwig++ as mentioned in this paper is a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton, leptonhadron and hadron-hadron collisions, with special emphasis on the correct description of radiation from heavy particles.
Abstract: In this paper we describe Herwig++ version 2.3, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of Beyond the Standard Model (BSM) physics includes a range of models and allows new models to be added by encoding the Feynman rules of the model. The parton-shower approach is used to simulate initial- and final-state QCD radiation, including colour coherence effects, with special emphasis on the correct description of radiation from heavy particles. The underlying event is simulated using an eikonal multiple parton-parton scattering model. The formation of hadrons from the quarks and gluons produced in the parton shower is described using the cluster hadronization model. Hadron decays are simulated using matrix elements, where possible including spin correlations and off-shell effects. Comment: 153 pages, program and additional information available from http://projects.hepforge.org/herwig . Updated description to Herwig++ version 2.3 and added one author
1,829 citations
TL;DR: In this article, a method to constrain parton distribution function (PDF) uncertainties in LHC observables, by effectively exploiting PDF-induced correlations with benchmark standard model cross sections, is presented.
Abstract: The latest CTEQ6.6 parton distributions, obtained by global analysis of hard-scattering data in the framework of general-mass perturbative QCD, are employed to study theoretical predictions and their uncertainties for significant processes at the Fermilab Tevatron and CERN Large Hadron Collider. The previously observed increase in predicted cross sections for the standard-candle W and Z boson production processes in the general-mass scheme (compared to those in the zero-mass scheme) is further investigated and quantified. A novel method to constrain parton distribution function (PDF) uncertainties in LHC observables, by effectively exploiting PDF-induced correlations with benchmark standard model cross sections, is presented. Using this method, we show that the tt cross section can potentially serve as a standard-candle observable for the LHC processes dominated by initial-state gluon scattering. Among other benefits, precise measurements of tt cross sections would reduce PDF uncertainties in predictions for single top-quark and Higgs boson production in the standard model and minimal supersymmetric standard model.
1,527 citations
TL;DR: Parton distribution functions (PDFs) are crucial ingredients for the calculation of the relevant cross sections for various scattering processes at the Large Hadron Collider (LHC). as mentioned in this paper found new PDFs, which will be important for the data analysis at the LHC Run-2.
Abstract: Parton distribution functions (PDFs) are crucial ingredients for the calculation of the relevant cross sections for various scattering processes at the Large Hadron Collider (LHC). Including data from several previous experiments, the authors find new PDFs, which will be important for the data analysis at the LHC Run-2.
1,521 citations
Book•
01 Jan 1972
TL;DR: Feynman as mentioned in this paper proposed the Parton Model and showed that it can be used to explain low-energy photon reactions at extreme energies and the properties of operators in momentum space.
Abstract: * Editors Foreword Richard P. Feynman * 15 General Theoretical Background * 68 Low Energy Photon Reactions * 810 Quark Model of Resonances * 1112 Pseudoscalar Meson Photoproduction, High Energy * 1314 t-Channel Exchange Phenomena * 1421 Vector Mesons and Vector Meson Dominance Hypothesis * 2224 Electromagnetic Form Factors * 2526 Electron-Proton Scattering. Deep Inelastic Region * 2633 Parton Model * 3435 Tests of the Parton Model * 3637 Inelastic Scattering As Properties of Operators * 38 Light Cone Algebra * 3941 Properties of Commutators in Momentum Space * 4247 Electromagnetic Self Energy * 4849 Other Two-Current Effects * 5051 Hypothesis in the Parton Model * 5254 Hadron-Hadron Collisions at Extreme Energies * 55 Final Hadronic States in Deep Inelastic Scattering * 5657 Partons as Quarks
1,394 citations