1,746,337 research outputs found
Parton distributions
Full text linkParton distributions, α(χ,μ(^₂) are essential ingredients for almost all theoretical calculations at hadron colliders. They give the number densities of the colliding par- tons (quarks and gluons) inside their parent hadrons at a given momentum fraction χand scale μ(^₂). The scale dependence of the parton distributions is given by DGLAP evolution, while the X dependence must be determined from a global analysis of deep-inelastic scattering (DIS) and related hard-scattering data. In Part I we introduce ‘doubly-unintegrateď parton distributions, fa(x, z, k(^₂),μ(^₂)), which additionally depend on the splitting fraction z and the transverse momentum (k) associated with the last evolution step. We show how these distributions can be used to calculate cross sections for inclusive jet production in DIS and compare the predictions to data taken at the HERA ep collider. We then calculate the transverse momentum distributions of พ and z bosons at the Tevatron pp collider and of Standard Model Higgs bosons at the forthcoming LHC. In Part II we study diffractive DIS, which is characterised by a large rapidity gap between the slightly deflected proton and the products of the virtual photon dissociation. We perform a novel QCD analysis of recent HERA data and extract diffractive parton distributions. The results of this analysis are used to investigate the effect of absorptive corrections in inclusive DIS. These absorptive corrections are due to the recombination of partons within the proton and are found to enhance the size of the gluon distribution at small X. We discuss the problem that the gluon distribution decreases with decreasing X at low scales while the sea quark distribution increases with decreasing X, whereas Regge theory predicts that both should have the same small-X behaviour. Our study hints at the possible importance of power corrections at low scales of around 1 GeV
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Dolly parton, songteller ::my life in lyrics /
No full textDolly Parton, Songteller: My Life in Lyrics is a landmark celebration of the remarkable life and career of a country music and pop culture legend. As told by Dolly Parton in her own inimitable words, explore the songs that have defined her journey. Illustrated throughout with previously unpublished images from Dolly Parton's personal and business archives. Mining over 60 years of songwriting, Dolly Parton highlights 150 of her songs and brings readers behind the lyrics. Packed with never-before-seen photographs and classic memorabilia Explores personal stories, candid insights, and myriad memories behind the songs Dolly Parton, Songteller: My Life in Lyrics reveals the stories and memories that have made Dolly a beloved icon across generations, genders, and social and international boundaries. Containing rare photos and memorabilia from Parton's archives, this book is a show-stopping must-have for every Dolly Parton fan. Learn the history behind classic Parton songs like "Jolene," "9 to 5," "I Will Always Love You," and more. The perfect gift for Dolly Parton fans (everyone loves Dolly!) as well as lovers of music history and country Add it to the shelf with books like Coat of Many Colors by Dolly Parton, The Beatles Anthology by The Beatles, and Born to Run by Bruce Springsteen
Parton, Leathel (Journalism) (n.d.) [handwritten; 3l.]
Full text linkTeacher narrative from Leathel E. Parton, untitled, undated, circa 1945https://scholarlycommons.pacific.edu/cook-nisei/1166/thumbnail.jp
Parton, Leathel (Journalism) (n.d.) [handwritten; 3l.]
No full textTeacher narrative from Leathel E. Parton, untitled, undated, circa 1945https://scholarlycommons.pacific.edu/cook-nisei/1166/thumbnail.jp
HERWIG 6: an event generator for Hadron emission reactions with interfering gluons (including supersymmetric processes)
Full text linkHERWIG is a general-purpose Monte Carlo event generator, which includes the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron scattering and soft hadron-hadron collisions in one package. It uses the parton-shower approach for initial- and final-state QCD radiation, including colour coherence effects and azimuthal correlations both within and between jets. This article updates the description of HERWIG published in 1992, emphasising the new features incorporated since then. These include, in particular, the matching of first-order matrix elements with parton showers, a more correct treatment of heavy quark decays, and a wide range of new processes, including many predicted by the Minimal Supersymmetric Standard Model, with the option of R-parity violation. At the same time we offer a brief review of the physics underlying HERWIG, together with details of the input and control parameters and the output data, to provide a self-contained guide for prospective users of the program
Monte Carlo simulations of hard QCD radiation
Full text linkMonte Carlo event generators, such as Herwig++, provide a full simulation of events at collider experiments. They give a fully exclusive description of hadronic final states and are therefore crucial tools for the planning of future experiments and analysing of data from existing experiments.
The key component that allows this description of high-multiplicity final states is the parton shower. There has been much recent progress improving the parton shower description of hard radiation using exact matrix elements. This thesis describes research into implementing and improving such methods within the Herwig++ event generator.
In Chapter 1, the parton-shower formalism is reviewed and the structure of event generators described. Chapter 2 details the specifics of the \textsf{Herwig++} parton shower.
In Chapters 3 and 4, the POWHEG next-to-leading-order matching procedure is described, and work implementing the scheme within Herwig++ is presented. The method is implemented for the processes e+e- to hadrons and Drell-Yan vector boson production and the results are compared to experimental data from LEP and the Tevatron. This work includes the first full implementation of the truncated shower.
A description of the development and implementation of a modified matrix-element merging scheme is presented in Chapter 5. This scheme is based on CKKW merging but uses an extension of the POWHEG idea to improve the method using truncated showers. The method is implemented first for final-state radiation in e+e- to hadrons and then, in Chapter 6, extended to include initial-state radiation in Drell-Yan vector boson production
Le travail social constructif: sources philosophiques et principes de pratique (Constructive social work: Philosophical roots and practice principles)
No full textParallelizations on products of spheres and octonionic geometry
No full textA classical theoremof Kervaire states that products of spheres are parallelizable if and only if at least one of the factors has odd dimension. Two explicit parallelizations on Sm × S2h−1 seem to be quite natural, and have been previously studied by the first named author in [32]. The present paper is devoted to the three choices G = G2, Spin(7), Spin(9) of G-structures on Sm × S2h−1, respectively with m + 2h − 1 = 7, 8, 16 and related with octonionic geometry
Multi-Parton Interactions at the LHC.
Full text linkWe review the recent progress in the theoretical description and experimental observation of multiple parton interactions. Subjects covered include experimental measurements of minimum bias in- teractions and of the underlying event, models of soft physics implemented in Monte Carlo generators, developments in the theoretical description of multiple parton interactions and phenomenological studies of double parton scattering. This article stems from contributions presented at the Helmholtz Alliance workshop on ”Multi-Parton Interactions at the LHC”, DESY Hamburg, 13-15 September 2010
Almost complex structures on spheres
Full text linkIn this paper we review the well-known fact that the only spheres admitting an almost complex structure are S2 and S6. The proof described here uses characteristic classes and the Bott periodicity theorem in topological K-theory. This paper originates from the talk “Almost Complex Structures on Spheres” given by the second author at the MAM1 workshop “(Non)-existence of complex structures on S6”, held in Marburg from March 27th to March 30th, 2017. It is a review paper, and as such no result is intended to be original. We tried to produce a clear, motivated and as much as possible self-contained exposition. © 2017 Elsevier B.V
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