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Sample records for generalized parton distributions

  1. Unraveling hadron structure with generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Andrei Belitsky; Anatoly Radyushkin

    2004-10-01

    The recently introduced generalized parton distributions have emerged as a universal tool to describe hadrons in terms of quark and gluonic degrees of freedom. They combine the features of form factors, parton densities and distribution amplitudes - the functions used for a long time in studies of hadronic structure. Generalized parton distributions are analogous to the phase-space Wigner quasi-probability function of non-relativistic quantum mechanics which encodes full information on a quantum-mechanical system. We give an extensive review of main achievements in the development of this formalism. We discuss physical interpretation and basic properties of generalized parton distributions, their modeling and QCD evolution in the leading and next-to-leading orders. We describe how these functions enter a wide class of exclusive reactions, such as electro- and photo-production of photons, lepton pairs, or mesons.

  2. From form factors to generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus

    2013-06-15

    I present an extraction of generalized parton distributions from selected data on the electromagnetic nucleon form factors. The extracted distributions can in particular be used to quantify the contribution to the proton spin from the total angular momentum carried by valence quarks, as well as their transverse spatial distribution inside the proton.

  3. Modeling the pion Generalized Parton Distribution

    CERN Document Server

    Mezrag, C

    2015-01-01

    We compute the pion Generalized Parton Distribution (GPD) in a valence dressed quarks approach. We model the Mellin moments of the GPD using Ans\\"atze for Green functions inspired by the numerical solutions of the Dyson-Schwinger Equations (DSE) and the Bethe-Salpeter Equation (BSE). Then, the GPD is reconstructed from its Mellin moment using the Double Distribution (DD) formalism. The agreement with available experimental data is very good.

  4. Hard exclusive reactions and generalized parton distributions

    Directory of Open Access Journals (Sweden)

    Hayrapetyan Avetik

    2015-01-01

    Full Text Available The recently developed formalism of Generalized Parton Distributions (GPDs allows connecting the experimental information of hard exclusive reactions to the spin contribution and even to the angular momentum contribution of quarks in the nucleon. By selecting different quantum numbers of the final state in exclusive productions, different GPDs can be addressed separately. The HERMES experiment at the HERA ring at DESY (Hamburg made pioneering contributions and first constraints to Generalized Parton Distributions (GPDs, using hard exclusive vector meson production (EVMP and Deeply Virtual Compton Scattering (DVCS. Using a novel recoil detector, HERMES managed to measure DVCS and EVMP free of any significant background. Selected results are highlighted and discussed in this paper.

  5. Momentum transfer dependence of generalized parton distributions

    CERN Document Server

    Sharma, Neetika

    2016-01-01

    We revisit the model for parametrization of momentum dependence of nucleon generalized parton distributions in the light of recent MRST measurements of parton distribution functions. Our parametrization method with minimum set of free parameters give a sufficiently good description of data for Dirac and Pauli electromagnetic form factors of proton and neutron at small and intermediate values of momentum transfer. We also calculate the GPDs for up and down quark by decomposing the electromagnetic form factors for nucleon using the charge and isospin symmetry and also study the evolution of GPDs to a higher scale. We further investigate the transverse charge densities for both the unpolarized and transversely polarized nucleon and compare our results with the Kelly's distribution.

  6. Generalized parton distributions of few body systems

    CERN Document Server

    Scopetta, S

    2007-01-01

    The relevance of measuring Generalized Parton Distributions (GPDs) for few nucleon systems is illustrated. An approach which permits to calculate the GPDs of hadrons made of composite constituents by proper convolutions is described. The application of the method to the nucleon target, assumed to be made of composite constituents is reviewed. Calculations of GPDs for few nucleon systems are summarized, with special emphasis to the $^3$He target.

  7. Generalized Valon Model for Double Parton Distributions

    Science.gov (United States)

    Broniowski, Wojciech; Ruiz Arriola, Enrique; Golec-Biernat, Krzysztof

    2016-06-01

    We show how the double parton distributions may be obtained consistently from the many-body light-cone wave functions. We illustrate the method on the example of the pion with two Fock components. The procedure, by construction, satisfies the Gaunt-Stirling sum rules. The resulting single parton distributions of valence quarks and gluons are consistent with a phenomenological parametrization at a low scale.

  8. Generalized Valon Model for Double Parton Distributions

    CERN Document Server

    Broniowski, Wojciech; Golec-Biernat, Krzysztof

    2016-01-01

    We show how the double parton distributions may be obtained consistently from the many-body light-cone wave functions. We illustrate the method on the example of the pion with two Fock components. The procedure, by construction, satisfies the Gaunt-Stirling sum rules. The resulting single parton distributions of valence quarks and gluons are consistent with a phenomenological parametrization at a low scale.

  9. Investigating generalized parton distribution in gravity dual

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Ryoichi, E-mail: ryoichi.nishio@ipmu.jp [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Chiba 277-8583 (Japan); Watari, Taizan [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Chiba 277-8583 (Japan)

    2012-02-01

    Generalized parton distribution (GPD) contains rich information of partons in a hadron, including transverse profile, and is also non-perturbative information necessary in describing a variety of hard processes, such as meson leptoproduction and double deeply virtual Compton scattering (DDVCS). In order to unveil non-perturbative aspects of GPD, we study DDVCS at small x in gravitational dual description. Using the complex spin j-plane representation of DDVCS amplitude, we show that GPD is well-defined and can be extracted from the amplitude even in the strong coupling regime. It also turns out that the saddle point value in the j-plane representation plays an important role; there are two phases in the imaginary part of amplitude of DDVCS and GPD, depending on relative position of the saddle point and the leading pole in the j-plane, and crossover between them is induced by the change of the kinematical variables. The saddle point value also directly controls kinematical variable dependence of many observables in one of the two phases, and indeed the dependence is qualitatively in nice agreement with HERA measurements. This Letter also serves as a brief summary of a preprint (arXiv:1105.2999).

  10. Some numerical studies of the evolution of generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, M.; Kugler, W.

    2007-11-15

    We study the evolution behavior of generalized parton distributions at small longitudinal momentum fraction. Particular attention is paid to the ratio of a generalized parton distribution and its forward limit, to the mixing between quarks and gluons, and to the dependence on the squared momentum transfer t. (orig.)

  11. Nucleon Generalized Parton Distributions from Full Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Robert Edwards; Philipp Haegler; David Richards; John Negele; Konstantinos Orginos; Wolfram Schroers; Jonathan Bratt; Andrew Pochinsky; Michael Engelhardt; George Fleming; Bernhard Musch; Dru Renner

    2007-07-03

    We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N_f=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm)^3.

  12. Generalized parton distributions and exclusive processes

    Energy Technology Data Exchange (ETDEWEB)

    Guzey, Vadim [Hampton U.

    2013-10-01

    In last fifteen years, GPDs have emerged as a powerful tool to reveal such aspects of the QCD structure of the nucleon as: - 3D parton correlations and distributions; - spin content of the nucleon. Further advances in the field of GPDs and hard exclusive processes rely on: - developments in theory and new methods in phenomenology such as new flexible parameterizations, neural networks, global QCD fits - new high-precision data covering unexplored kinematics: JLab at 6 and 12 GeV, Hermes with recoil detector, Compass, EIC. This slide-show presents: Nucleon structure in QCD, particularly hard processes, factorization and parton distributions; and a brief overview of GPD phenomenology, including basic properties of GPDs, GPDs and QCD structure of the nucleon, and constraining GPDs from experiments.

  13. Nucleon generalized parton distributions from full lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Haegler, P. [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Theoretische Physik; Schroers, W. [DESY, Zeuthen (Germany). John von Neumann-Institut fuer Computing NIC; Bratt, J.; Negele, J.W.; Pochinsky, A.V. [Massachusetts Institute of Technology, Cambridge, MA (US). Center for Theoretical Physics] (and others)

    2007-07-15

    We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N{sub f}=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm){sup 3}. (orig.)

  14. QCD Sum Rules and Models for Generalized Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Anatoly Radyushkin

    2004-10-01

    I use QCD sum rule ideas to construct models for generalized parton distributions. To this end, the perturbative parts of QCD sum rules for the pion and nucleon electromagnetic form factors are interpreted in terms of GPDs and two models are discussed. One of them takes the double Borel transform at adjusted value of the Borel parameter as a model for nonforward parton densities, and another is based on the local duality relation. Possible ways of improving these Ansaetze are briefly discussed.

  15. Concurrent approaches to Generalized Parton Distribution modeling: the pion's case

    Science.gov (United States)

    Chouika, N.; Mezrag, C.; Moutarde, H.; Rodríguez-Quintero, J.

    2017-03-01

    The concept of Generalized Parton Distributions promises an understanding of the generation of the charge, spin, and energy-momentum structure of hadrons by quarks and gluons. Forthcoming measurements with unprecedented accuracy at Jefferson Lab and at CERN will challenge our quantitative description of the three-dimensional structure of hadrons. To fully exploit these future measurements, new tools and models are currently being developed. We explain the difficulties of Generalized Parton Distribution modeling, and present some recent progresses. In particular we describe the symmetry-preserving Dyson-Schwinger and Bethe-Salpeter framework. We also discuss various equivalent parameterizations and sketch how to combine them to obtain models satisfying a priori all required theoretical constraints. At last we explain why these developments naturally fit in a versatile software framework, named PARTONS, dedicated to the theory and phenomenology of GPDs.

  16. Hadron tomography studies by generalized parton distributions and distribution amplitudes

    CERN Document Server

    Kumano, S

    2016-01-01

    We discuss hadron-tomography studies for the nucleon and exotic hadrons by high-energy hadron reactions. First, the constituent-counting rule is explained for determining internal quark configurations of exotic-hadron candidates by scaling properties of high-energy exclusive cross sections. Next, possibilities are discussed for investigating the generalized parton distributions (GPDs) of the nucleon and exotic hadrons at J-PARC. In particular, we study hadronic $2 \\to 3$ process $p+p \\to N+\\pi+B$, exclusive Drell-Yan process, and exotic-hadron GPDs. For determining three-dimensional structure of unstable exotic hadrons, we consider $s$-$t$ crossed quantities of the GPDs called generalized distribution amplitudes (GDAs), which can be investigated at KEKB. We explain possible studies of the GDAs by two-photon processes.

  17. Timelike Compton scattering off the neutron and generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Boer, M.; Guidal, M. [CNRS-IN2P3, Universite Paris-Sud, Institut de Physique Nucleaire d' Orsay, Orsay (France); Vanderhaeghen, M. [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2016-02-15

    We study the exclusive photoproduction of an electron-positron pair on a neutron target in the Jefferson Lab energy domain. The reaction consists of two processes: the Bethe-Heitler and the Timelike Compton Scattering. The latter process provides potentially access to the Generalized Parton Distributions (GPDs) of the nucleon. We calculate all the unpolarized, single- and double-spin observables of the reaction and study their sensitivities to GPDs. (orig.)

  18. Timelike Compton scattering off the proton and generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Boer, M.; Guidal, M. [Universite Paris-Sud, Institut de Physique Nucleaire d' Orsay, CNRS-IN2P3, Orsay (France); Vanderhaeghen, M. [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2015-08-15

    We study the exclusive photoproduction of a lepton pair off the proton with the aim of studying the proton quark structure via the Generalized Parton Distributions (GPD) formalism. After deriving the amplitudes of the processes contributing to the γP → P' e{sup +}e{sup -}, the timelike Compton scattering and the Bethe-Heitler process, we calculate all unpolarized, single- and double- spin beam-target observables in the valence region in terms of GPDs. (orig.)

  19. Deep Exclusive Scattering and Generalized Parton Distributions : Experimental Review

    Energy Technology Data Exchange (ETDEWEB)

    Franck Sabatie

    2004-10-01

    Since the Generalized Parton Distribution theoretical framework was introduced in the late 90's, a few published and numerous preliminary results from Deep Exclusive Scattering (DES) have been extracted from non-dedicated experiments at HERA and Jefferson Lab. We review most of these results, comment on the ongoing dedicated research in this topic and conclude with the expectations from the next generation of experiments in the near future.

  20. Deeply Pseudoscalar Meson Electroproduction with CLAS and Generalized Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Guidal, Michel [Institut de Physique Nucleaire, Orsay (France); Kubarovsky, Valery P. [Jefferson Lab., Newport News, VA (United States)

    2015-06-01

    We discuss the recent data of exclusive $\\pi^0$ (and $\\pi^+$) electroproduction on the proton obtained by the CLAS collaboration at Jefferson Lab. It is observed that the cross sections, which have been decomposed in $\\sigma_T+\\epsilon\\sigma_L$, $\\sigma_{TT}$ and $\\sigma_{LT}$ structure functions, are dominated by transverse amplitude contributions. The data can be interpreted in the Generalized Parton Distribution formalism provided that one includes helicity-flip transversity GPDs.

  1. Crossing and Radon Tomography for Generalized Parton Distributions

    CERN Document Server

    Teryaev, O V

    2001-01-01

    The crossing properties of the matrix elements of non-local operators, parameterized by Generalized Parton Distribution, are considered. They are especially simple in terms of the Double Distributions which are common for the various kinematical regions. As a result, Double Distributions may be in principle extracted from the combined data in these regions by making use of the inverse Radon transform, known as a standard method in tomography. The ambiguities analogous to the ones for the vetor potential in the two-dimensional magneto-statics are outlined. The possible generalizations are discussed.

  2. Moments of nucleon generalized parton distributions from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Carbonell, J.; Harraud, P.A.; Papinutto, M. [UJF/CNRS/IN2P3, Grenoble (France). Lab. de Physique Subatomique et Cosmologie; Constantinou, M.; Kallidonis, C. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Guichon, P. [CEA-Saclay, Gif-sur-Yvette (France). IRFU-Service de Physique Nucleaire; Jansen, K. [DESY, Zeuthen (Germany). NIC; Korzec, T. [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Humboldt Univ. Berlin (Germany). Inst. fuer Physik

    2011-07-15

    We present results on the lower moments of the nucleon generalized parton distributions within lattice QCD using two dynamical flavors of degenerate twisted mass fermions. Our simulations are performed on lattices with three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm, allowing the investigation of cut-off effects. The volume dependence is examined using simulations on two lattices of spatial length L=2.1 fm and L=2.8 fm. The simulations span pion masses in the range of 260-470 MeV. Our results are renormalized nonperturbatively and the values are given in the MS scheme at a scale {mu}=2 GeV. They are chirally extrapolated to the physical point in order to compare with experiment. The consequences of these results on the spin carried by the quarks in the nucleon are investigated. (orig.)

  3. Nucleon form factors, generalized parton distributions and quark angular momentum

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kroll, Peter [Bergische Univ., Wuppertal (Germany). Fachbereich Physik; Regensburg Univ. (Germany). Institut fuer Theoretische Physik

    2013-02-15

    We extract the individual contributions from u and d quarks to the Dirac and Pauli form factors of the proton, after a critical examination of the available measurements of electromagnetic nucleon form factors. From this data we determine generalized parton distributions for valence quarks, assuming a particular form for their functional dependence. The result allows us to study various aspects of nucleon structure in the valence region. In particular, we evaluate Ji's sum rule and estimate the total angular momentum carried by valence quarks at the scale {mu}=2 GeV to be J{sup u}{sub v}=0.230{sup +0.009}{sub -0.024} and J{sup d}{sub v}=-0.004{sup +0.010}{sub -0.016}.

  4. Deeply Virtual Exclusive Processes and Generalized Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    ,

    2011-06-01

    The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep {yields} ep{gamma} in Hall A support the QCD factorization of the scattering amplitude for Q^2 {>=} 2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e, e'p{gamma} ) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The {rho} and {omega} channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the {phi}-production channel is dominated by the gluon distribution.

  5. Dual parametrization of generalized parton distributions in two equivalent representations

    CERN Document Server

    Müller, Dieter; Semenov-Tian-Shansky, Kirill M

    2014-01-01

    The dual parametrization and the Mellin-Barnes integral approach represent two frameworks for handling the double partial wave expansion of generalized parton distributions (GPDs) in the conformal partial waves and in the $t$-channel ${\\rm SO}(3)$ partial waves. Within the dual parametrization framework, GPDs are represented as integral convolutions of forward-like functions whose Mellin moments generate the conformal moments of GPDs. The Mellin-Barnes integral approach is based on the analytic continuation of the GPD conformal moments to the complex values of the conformal spin. GPDs are then represented as the Mellin-Barnes-type integrals in the complex conformal spin plane. In this paper we explicitly show the equivalence of these two independently developed GPD representations. Furthermore, we clarify the notions of the $J=0$ fixed pole and the $D$-form factor. We also provide some insight into GPD modeling and map the phenomenologically successful Kumeri\\v{c}ki-M\\"uller GPD model to the dual parametrizat...

  6. Towards a model of pion generalized parton distributions from Dyson-Schwinger equations

    Energy Technology Data Exchange (ETDEWEB)

    Moutarde, H. [CEA, Centre de Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette (France)

    2015-04-10

    We compute the pion quark Generalized Parton Distribution H{sup q} and Double Distributions F{sup q} and G{sup q} in a coupled Bethe-Salpeter and Dyson-Schwinger approach. We use simple algebraic expressions inspired by the numerical resolution of Dyson-Schwinger and Bethe-Salpeter equations. We explicitly check the support and polynomiality properties, and the behavior under charge conjugation or time invariance of our model. We derive analytic expressions for the pion Double Distributions and Generalized Parton Distribution at vanishing pion momentum transfer at a low scale. Our model compares very well to experimental pion form factor or parton distribution function data.

  7. Nucleon-generalized parton distributions in the light-front quark model

    Indian Academy of Sciences (India)

    Neetika Sharma

    2016-02-01

    We calculate the generalized parton distributions (GPDs) for the up- and downquarks in nucleon using the effective light-front wavefunction. The results obtained for GPDs in momentum and impact parameter space are comparable with phenomenological parametrization methods.

  8. Moments of nucleon generalized parton distributions from lattice QCD

    CERN Document Server

    Alexandrou, C; Constantinou, M; Harraud, P A; Guichon, P; Jansen, K; Kallidonis, C; Korzec, T; Papinutto, M

    2011-01-01

    We present results on the lower moments of the nucleon generalized parton distri butions within lattice QCD using two dynamical flavors of degenerate twisted mass fermions. Our simulations are performed on lattices with three different values of the lattice spacings, namely $a=0.089$ fm, $a=0.070$ fm and $a=0.056$ fm, allowing the investigation of cut-off effects. The volume dependence is examined using simulations on two lattices of spatial length $L=2.1$ fm and $L=2.8$ fm. The simulations span pion masses in the range of 260-470 MeV. Our results are renormalized non-perturbatively and the values are given in the $\\bar{\\rm MS}$ scheme at a scale $ \\mu=2$ GeV. They are chirally extrapolated to the physical point in order to compare with experiment. The consequences of these results on the spin carried by the quarks in the nucleon are investigated.

  9. Unintegrated double parton distributions

    CERN Document Server

    Golec-Biernat, K

    2016-01-01

    We present the construction of unintegrated double parton distribution functions which include dependence on transverse momenta of partons. We extend the formulation which was used to obtain the single unintegrated parton distributions from the standard, integrated parton distribution functions. Starting from the homogeneous part of the evolution equations for the integrated double parton distributions, we construct the unintegrated double parton distributions as the convolutions of the integrated double distributions and the splitting functions, multiplied by the Sudakov form factors. We show that there exist three domains of external hard scales which require three distinct forms of the unintegrated double distributions. The additional transverse momentum dependence which arises through the Sudakov form factors leads to non-trivial correlations in the parton momenta. We also discuss the non-homogeneous contribution to the unintegrated double parton distributions, which arises due to the splitting of a singl...

  10. Chiral perturbation theory for generalized parton distributions and baryon distribution amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Wein, Philipp

    2016-05-06

    In this thesis we apply low-energy effective field theory to the first moments of generalized parton distributions and to baryon distribution amplitudes, which are both highly relevant for the parametrization of the nonperturbative part in hard processes. These quantities yield complementary information on hadron structure, since the former treat hadrons as a whole and, thus, give information about the (angular) momentum carried by an entire parton species on average, while the latter parametrize the momentum distribution within an individual Fock state. By performing one-loop calculations within covariant baryon chiral perturbation theory, we obtain sensible parametrizations of the quark mass dependence that are ideally suited for the subsequent analysis of lattice QCD data.

  11. Parton Distribution Function Uncertainties

    CERN Document Server

    Giele, Walter T.; Kosower, David A.; Giele, Walter T.; Keller, Stephane A.; Kosower, David A.

    2001-01-01

    We present parton distribution functions which include a quantitative estimate of its uncertainties. The parton distribution functions are optimized with respect to deep inelastic proton data, expressing the uncertainties as a density measure over the functional space of parton distribution functions. This leads to a convenient method of propagating the parton distribution function uncertainties to new observables, now expressing the uncertainty as a density in the prediction of the observable. New measurements can easily be included in the optimized sets as added weight functions to the density measure. Using the optimized method nowhere in the analysis compromises have to be made with regard to the treatment of the uncertainties.

  12. Generalized parton distributions of the pion in a covariant Bethe-Salpeter model and light-front models

    CERN Document Server

    Frederico, T; Pasquini, B; Salme', G

    2009-01-01

    The generalized parton distributions of the pion are studied within different light-front approaches for the quark-hadron and quark-photon vertices, exploring different kinematical regions in both the valence and non-valence sector. Moments of the generalized parton distributions which enter the definition of generalized form factors are also compared with recent lattice calculations.

  13. The effects of nuclear structure on generalized parton distributions of 3He

    CERN Document Server

    Scopetta, S

    2005-01-01

    The effect of the nuclear medium on generalized parton distributions (GPDs) is studied for the 3He nucleus, through a realistic microscopic analysis. In Impulse Approximation, Fermi motion and binding effects, evaluated by modern potentials, are found to be larger than in the forward case and very sensitive to the details of nuclear structure at short distances.

  14. Probing moments of baryon-antibaryon generalized parton distributions at BELLE and FAIR

    CERN Document Server

    Kroll, P

    2013-01-01

    We analyze the time-like processes gamma gamma -> B Bbar and p p-bar -> gamma M at large Mandelstam variables within the handbag approach for which the process amplitudes factorize in hard partonic subprocesses and annihilation form factor. The latter represent moments of baryon-antibaryon generalized parton distributions. Symmetry relations restrict the number of independent annihilation form factors for the ground state baryons drastically. We determine these form factors from the present BELLE data on gamma gamma -> B Bbar with the help of simplifying assumptions. The knowledge of these form factors allow for predictions of p pbar -> gamma M for various mesons which may be probed at FAIR.

  15. First moments of the nucleon generalized parton distributions from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Sternbeck, A.; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Haegler, P. [Mainz Univ. (DE). Inst. fuer Kernphysik] (and others)

    2012-03-15

    We report on our lattice calculations of the nucleon's generalized parton distributions (GPDs), concentrating on their first moments for the case of N{sub f}=2. Due to recent progress on the numerical side we are able to present results for the generalized form factors at pion masses as low as 260 MeV. We perform a fit to one-loop covariant baryon chiral perturbation theory with encouraging results.

  16. Parton Distributions Working Group

    Energy Technology Data Exchange (ETDEWEB)

    de Barbaro, L.; Keller, S. A.; Kuhlmann, S.; Schellman, H.; Tung, W.-K.

    2000-07-20

    This report summarizes the activities of the Parton Distributions Working Group of the QCD and Weak Boson Physics workshop held in preparation for Run II at the Fermilab Tevatron. The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, the authors introduce a Manifesto that describes an optimal method for reporting data.

  17. Pion generalized parton distributions within a fully covariant constituent quark model

    Energy Technology Data Exchange (ETDEWEB)

    Fanelli, Cristiano [Massachusetts Institute of Technology, Cambridge, MA (United States). Lab. for Nuclear Science; Pace, Emanuele [' ' Tor Vergata' ' Univ., Rome (Italy). Physics Dept.; INFN Sezione di TorVergata, Rome (Italy); Romanelli, Giovanni [Rutherford-Appleton Laboratory, Didcot (United Kingdom). STFC; Salme, Giovanni [Istituto Nazionale di Fisica Nucleare, Rome (Italy); Salmistraro, Marco [Rome La Sapienza Univ. (Italy). Physics Dept.; I.I.S. G. De Sanctis, Rome (Italy)

    2016-05-15

    We extend the investigation of the generalized parton distribution for a charged pion within a fully covariant constituent quark model, in two respects: (1) calculating the tensor distribution and (2) adding the treatment of the evolution, needed for achieving a meaningful comparison with both the experimental parton distribution and the lattice evaluation of the so-called generalized form factors. Distinct features of our phenomenological covariant quark model are: (1) a 4D Ansatz for the pion Bethe-Salpeter amplitude, to be used in the Mandelstam formula for matrix elements of the relevant current operators, and (2) only two parameters, namely a quark mass assumed to be m{sub q} = 220 MeV and a free parameter fixed through the value of the pion decay constant. The possibility of increasing the dynamical content of our covariant constituent quark model is briefly discussed in the context of the Nakanishi integral representation of the Bethe-Salpeter amplitude. (orig.)

  18. Leading twist nuclear shadowing, nuclear generalized parton distributions and nuclear DVCS at small x

    Energy Technology Data Exchange (ETDEWEB)

    Guzey, Vadim; Goeke, Klaus; Siddikov, Marat

    2009-01-01

    We generalize the leading twist theory of nuclear shadowing and calculate quark and gluon generalized parton distributions (GPDs) of spinless nuclei. We predict very large nuclear shadowing for nuclear GPDs. In the limit of the purely transverse momentum transfer, our nuclear GPDs become impact parameter dependent nuclear parton distributions (PDFs). Nuclear shadowing induces non-trivial correlations between the impact parameter $b$ and the light-cone fraction $x$. We make predictions for the deeply virtual Compton scattering (DVCS) amplitude and the DVCS cross section on $^{208}$Pb at high energies. We calculate the cross section of the Bethe-Heitler (BH) process and address the issue of the extraction of the DVCS signal from the $e A \\to e \\gamma A$ cross section. We find that the $e A \\to e \\gamma A$ differential cross section is dominated by DVCS at the momentum transfer $t$ near the minima of the nuclear form factor. We also find that nuclear shadowing leads

  19. Helicity dependent parton distributions

    CERN Document Server

    Scopetta, Sergio; 10.4249/scholarpedia.10226

    2011-01-01

    The helicity dependent parton distributions describe the number density of partons with given longitudinal momentum x and given polarization in a hadron polarized longitudinally with respect to its motion. After the discovery, more than 70 years ago, that the proton is not elementary, the observation of Bjorken scaling in the late 1960s lead to the idea of hadrons containing almost pointlike constituents, the partons. Since then, Deep Inelastic Scattering (DIS) has played a crucial role in our understanding of hadron structure. Through DIS experiments it has been possible to link the partons to the quarks, and to unveil the presence of other pointlike constituents, the gluons, which lead into a dynamical theory of quarks and gluons - quantum chromodynamics (QCD). Polarized DIS, i.e. the collision of a longitudinally polarized lepton beam on a polarized target (either longitudinally or transversely polarized), provides a complementary information regarding the structure of the nucleon. Whereas ordinary DIS pro...

  20. Probing moments of baryon-antibaryon generalized parton distributions at BELLE and FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, P. [Universitaet Regensburg, Institut fuer Theoretische Physik, Regensburg (Germany); Universitaet Wuppertal, Fachbereich Physik, Wuppertal (Germany); Schaefer, A. [Universitaet Regensburg, Institut fuer Theoretische Physik, Regensburg (Germany)

    2014-01-15

    We analyze the time-like processes {gamma}{gamma}{yields}BB and p anti p{yields}{gamma}M at large Mandelstam variables within the handbag approach, for which the process amplitudes factorize in hard partonic subprocesses and annihilation form factors. The latter represent moments of baryon-antibaryon generalized parton distributions (GPDs). Symmetry relations restrict the number of independent annihilation form factors for the ground state baryons drastically. We determine these form factors from the present BELLE data on {gamma}{gamma}{yields}BB with the help of simplifying assumptions. The knowledge of these form factors allow for predictions of p anti p{yields}{gamma}M for various mesons which may be probed at FAIR. (orig.)

  1. Parton Distributions Working Group

    CERN Document Server

    de Barbaro, Lucy; Brock, R.; Casey, D.; Demina, R.; Giele, W.T.; Hirosky, R.; Huston, J.; Kalk, J.; Keller, S.A.; Klasen, M.; Kosower, D.A.; Kramer, M.; Kretzer, S.; Kuhlmann, S.; Martin, R.; Olness, Fredrick I.; Plehn, T.; Pumplin, J.; Scalise, R.J.; Schellman, H.; Smith, J.; Soper, D.E.; Sterman, George F.; Stump, D.; Tung, W.K.; Varelas, N.; Vogelsang, W.; Yang, Un-Ki

    2000-01-01

    The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, we introduce a "Manifesto" that describes an optimal method for reporting data.

  2. Polarized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    de Florian, D.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Sassot, R. (Laboratorio de Fisica Teorica, Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67-1900 La Plata (Argentina))

    1995-01-01

    We analyze spin-dependent parton distributions consistent with the most recent measurements of the spin-dependent deep inelastic scattering structure functions and obtained in the framework of the spin dilution model. Predictions for the doubly polarized proton-proton Drell-Yan asymmetry, for the high [ital p][sub [ital T

  3. Cross-channel analysis of quark and gluon generalized parton distributions with helicity flip

    Energy Technology Data Exchange (ETDEWEB)

    Pire, B. [CNRS, CPhT, Ecole Polytechnique, Palaiseau (France); Semenov-Tian-Shansky, K. [Universite de Liege, IFPA, Departement AGO, Liege (Belgium); Szymanowski, L. [National Centre for Nuclear Research (NCBJ), Warsaw (Poland); Wallon, S. [Universite de Paris-Sud, CNRS, LPT, Orsay (France); Universite Paris 06, Faculte de Physique, UPMC, Paris (France)

    2014-05-15

    Quark and gluon helicity flip generalized parton distributions (GPDs) address the transversity quark and gluon structure of the nucleon. In order to construct a theoretically consistent parametrization of these hadronic matrix elements, we work out the set of combinations of those GPDs suitable for the SO(3) partial wave (PW) expansion in the cross-channel. This universal result will help to build up a flexible parametrization of these important hadronic non-perturbative quantities, using, for instance, the approaches based on the conformal PW expansion of GPDs such as the Mellin-Barnes integral or the dual parametrization techniques. (orig.)

  4. Form Factors and Generalized Parton Distributions in Basis Light-Front Quantization

    CERN Document Server

    Adhikari, Lekha; Zhao, Xingbo; Maris, Pieter; Vary, James P; El-Hady, Alaa Abd

    2016-01-01

    We calculate the elastic form factors and the Generalized Parton Distributions (GPDs) for four low-lying bound states of a demonstration fermion-antifermion system, strong coupling positronium ($e \\bar{e}$), using Basis Light-Front Quantization (BLFQ). Using this approach, we also calculate the impact-parameter dependent GPDs $q(x, {\\vec b_\\perp})$ to visualize the fermion density in the transverse plane (${\\vec b_\\perp}$). We compare selected results with corresponding quantities in the non-relativistic limit to reveal relativistic effects. Our results establish the foundation within BLFQ for investigating the form factors and the GPDs for hadronic systems.

  5. Parton Distributions in Impact Parameter Space

    CERN Document Server

    Dahiya, H; Ray, S

    2007-01-01

    Fourier transform of the generalized parton distributions (GPDs) at zero skewness with respect to the transverse momentum transfer gives the distribution of partons in the impact parameter space. We investigate the GPDs as well as the impact parameter dependent parton distributions (ipdpdfs) by expressing them in terms of overlaps of light front wave functions (LFWFs) and present a comparative study using three different model LFWFs.

  6. Coherent deeply virtual Compton scattering off 3He and neutron generalized parton distributions

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2014-06-01

    Full Text Available It has been recently proposed to study coherent deeply virtual Compton scattering (DVCS off 3He nuclei to access neutron generalized parton distributions (GPDs. In particular, it has been shown that, in Impulse Approximation (IA and at low momentum transfer, the sum of the quark helicity conserving GPDs of 3He, H and E, is dominated by the neutron contribution. This peculiar result makes the 3He target very promising to access the neutron information. We present here the IA calculation of the spin dependent GPD H See Formula in PDF of 3He. Also for this quantity the neutron contribution is found to be the dominant one, at low momentum transfer. The known forward limit of the IA calculation of H See Formula in PDF , yielding the polarized parton distributions of 3He, is correctly recovered. The extraction of the neutron information could be anyway non trivial, so that a procedure, able to take into account the nuclear effects encoded in the IA analysis, is proposed. These calculations, essential for the evaluation of the coherent DVCS cross section asymmetries, which depend on the GPDs H,E and H See Formula in PDF , represent a crucial step for planning possible experiments at Jefferson Lab.

  7. Nuclear parton distributions

    Directory of Open Access Journals (Sweden)

    Kulagin S. A.

    2017-01-01

    Full Text Available We review a microscopic model of the nuclear parton distribution functions, which accounts for a number of nuclear effects including Fermi motion and nuclear binding, nuclear meson-exchange currents, off-shell corrections to bound nucleon distributions and nuclear shadowing. We also discuss applications of this model to a number of processes including lepton-nucleus deep inelastic scattering, proton-nucleus Drell-Yan lepton pair production at Fermilab, as well as W± and Z0 boson production in proton-lead collisions at the LHC.

  8. Generalized parton distributions: confining potential effects within AdS/QCD

    Energy Technology Data Exchange (ETDEWEB)

    Traini, Marco [Universite Paris Saclay, CEA, Institut de Physique Theorique, Gif-sur-Yvette (France); Universita degli Studi di Trento, Dipartimento di Fisica, Trento (Italy); INFN-TIFPA, Trento (Italy)

    2017-04-15

    Generalized parton distributions are investigated within a holographic approach where the string modes in the fifth dimension describe the nucleon in a bottom-up or AdS/QCD framework. The aim is to bring the AdS/QCD results in the realm of phenomenology in order to extract consequences and previsions. Two main aspects are studied: (i) the role of the confining potential needed for breaking conformal invariance and introducing confinement (both: classic soft-wall and recent infra-red potentials are investigated); (ii) the extension of the predicted GPDs to the entire range of off-forward kinematics by means of double distributions. Higher Fock states are included describing the nucleon as a superposition of three valence quarks and quark-antiquark pairs and gluons. (orig.)

  9. Integrated and Unintegrated Parton Distributions

    Institute of Scientific and Technical Information of China (English)

    方洁; 阮建红

    2011-01-01

    We compare the twist-2 and twist-4 parton distributions both in integrated and unintegrated parton distributions. We find that when x decreases the difference between the twist-2 and twist-4 patton distributions become obvious except for the valence quark distributions. We hope the future experiments may distinguish whether the twist-4 correction is needed or not and select a reasonable unintegrated parton distribution model

  10. Accessing Generalized Parton Distributions in Exclusive Photoproduction of a $\\gamma \\rho$ Pair with a Large Invariant Mass

    CERN Document Server

    Boussarie, R; Szymanowski, L; Wallon, S

    2016-01-01

    We propose and study the photoproduction of a $\\gamma\\,\\rho$ pair with a large invariant mass and a small transverse momentum of the final nucleon, as a way to access generalized parton distributions. In the kinematics of JLab 12-GeV, we demonstrate the feasibility of this measurement.

  11. Nuclear Parton Distribution Functions

    Energy Technology Data Exchange (ETDEWEB)

    I. Schienbein, J.Y. Yu, C. Keppel, J.G. Morfin, F. Olness, J.F. Owens

    2009-06-01

    We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a {chi}{sup 2} analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x{sub Bj}-dependent and Q{sup 2}-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x{sub Bj}, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.

  12. Unintegrated Double Parton Distributions - a Summary

    CERN Document Server

    Golec-Biernat, Krzysztof

    2016-01-01

    We present main elements of the construction of unintegrated double parton distribution functions which depend on transverse momenta of partons. We follow the method proposed by Kimber, Martin and Ryskin for a construction of unintegrated single parton distributions from the standard parton distribution functions.

  13. AdS/QCD and Deep Inelastic Scattering on nucleon: Generalized Parton Distributions and the role of the confining potential

    CERN Document Server

    Traini, Marco Claudio

    2016-01-01

    Generalized Parton Distributions are investigated within an holographic approach where the string modes in the fifth dimension describe the nucleon in a bottom-up framework of the AdS/CFT duality. Conformal invariance and confinement are introduced by means of an Infra-Red improved dilaton and potential model. Higher Fock states are included describing the nucleon as a superposition of three valence quarks and quark-antiquark pairs and gluons. A method to solve general confining potentials is introduced and it makes use of an expansion on the complete set of the linear Soft Wall model solutions.

  14. Parametrization of nuclear parton distributions

    Indian Academy of Sciences (India)

    M Hirai; S Kumano; M Miyama

    2001-08-01

    Optimum nuclear parton distributions are obtained by analysing available experimental data on electron and muon deep inelastic scattering (DIS). The distributions are given at 2 = 1 GeV2 with a number of parameters, which are determined by a 2 analysis of the data. Valencequark distributions are relatively well determined at medium , but they are slightly dependent on the assumed parametrization form particularly at small . Although antiquark distributions are shadowed at small , their behavior is not obvious at medium from the 2 data. The gluon distributions could not be restricted well by the inclusive DIS data; however, the analysis tends to support the gluon shadowing at small . We provide analytical expressions and computer subroutines for calculating the nuclear parton distributions, so that other researchers could use them for applications to other high-energy nuclear reactions.

  15. Structure functions and parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.D.; Stirling, W.J. [Univ. of Durham (United Kingdom); Roberts, R.G. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom)

    1995-07-01

    The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.

  16. Modelling the nuclear parton distributions

    CERN Document Server

    Kulagin, S A

    2016-01-01

    We review a semi-microscopic model of nuclear parton distributions, which takes into account a number of nuclear effects including Fermi motion and nuclear binding, nuclear meson-exchange currents and off-shell corrections to bound nucleon distributions as well as nuclear shadowing effect. We also discuss applications of the model to the lepton-nuclear deep-inelastic scattering, Drell-Yan process and neutrino total cross sections.

  17. Parton distributions with threshold resummation

    CERN Document Server

    Bonvini, Marco; Rojo, Juan; Rottoli, Luca; Ubiali, Maria; Ball, Richard D; Bertone, Valerio; Carrazza, Stefano; Hartland, Nathan P

    2015-01-01

    We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the NNPDF3.0 analysis, are extracted from deep-inelastic scattering, Drell-Yan, and top quark pair production data, for which resummed calculations can be consistently used. We find that, close to threshold, the inclusion of resummed PDFs can partially compensate the enhancement in resummed matrix elements, leading to resummed hadronic cross-sections closer to the fixed-order calculation. On the other hand, far from threshold, resummed PDFs reduce to their fixed-order counterparts. Our results demonstrate the need for a consistent use of resummed PDFs in resummed calculations.

  18. Practical quasi parton distribution functions

    CERN Document Server

    Ishikawa, Tomomi; Qiu, Jian-Wei; Yoshida, Shinsuke

    2016-01-01

    A completely new strategy to calculate parton distribution functions on the lattice has recently been proposed. In this method, lattice calculable observables, called quasi distributions, are related to normal distributions. The quasi distributions are known to contain power-law UV divergences arise from a Wilson line in the non-local operator, while the normal distributions only have logatithmic UV divergences. We propose possible method to subtract the power divegence to make the matching of the quasi with the normal distributions well-defined. We also demonstrate the matching of the quasi quark distribution between continuum and lattice implementing the power divergence subtraction. The matching calculations are carried out by one-loop perturbation.

  19. Parton distributions with LHC data

    DEFF Research Database (Denmark)

    Ball, R.D.; Deans, C.S.; Del Debbio, L.;

    2013-01-01

    We present the first determination of parton distributions of the nucleon at NLO and NNLO based on a global data set which includes LHC data: NNPDF2.3. Our data set includes, besides the deep inelastic, Drell-Yan, gauge boson production and jet data already used in previous global PDF determinati......We present the first determination of parton distributions of the nucleon at NLO and NNLO based on a global data set which includes LHC data: NNPDF2.3. Our data set includes, besides the deep inelastic, Drell-Yan, gauge boson production and jet data already used in previous global PDF...... determinations, all the relevant LHC data for which experimental systematic uncertainties are currently available: ATLAS and LHCb W and Z rapidity distributions from the 2010 run, CMS W electron asymmetry data from the 2011 run, and ATLAS inclusive jet cross-sections from the 2010 run. We introduce an improved...... implementation of the FastKernel method which allows us to fit to this extended data set, and also to adopt a more effective minimization methodology. We present the NNPDF2.3 PDF sets, and compare them to the NNPDF2.1 sets to assess the impact of the LHC data. We find that all the LHC data are broadly consistent...

  20. Deeply virtual Compton scattering with the CLAS detector for the study of generalized parton distributions; Diffusion compton profondement virtuelle avec le detecteur CLAS pour une etude des distributions de partons generalisees

    Energy Technology Data Exchange (ETDEWEB)

    Girod, F.X

    2006-12-15

    The structure of the nucleon, among the first fundamental problems in hadronic physics, is the subject of a renewed interest. The lightest baryonic state has historically been described in two complementary approaches: through elastic scattering, measuring form factors which reflect the spatial shape of charge distributions, and through deep inelastic scattering, providing access to parton distribution functions which encode the momentum content carried by the constituents. The recently developed formalism of Generalized Parton Distributions unifies those approaches and provides access to new informations. The cleanest process sensitive to GPDs is the deeply virtual Compton scattering (DVCS) contributing to the ep {yields} ep{gamma} reaction. This work deals with a dedicated experiment accomplished with the CLAS detector, completed with two specific equipments: a lead tungstate calorimeter covering photon detection at small angles, and a superconducting solenoid actively shielding the electromagnetic background. The entire project is covered: from the upgrade of the experimental setup, through the update of the software, data taking and analysis, up to a first comparison of the beam spin asymmetry to model predictions. (author)

  1. Spin-flavor structure of chiral-odd generalized parton distributions in the large-Nc limit

    Science.gov (United States)

    Schweitzer, P.; Weiss, C.

    2016-10-01

    We study the spin-flavor structure of the nucleon's chiral-odd generalized parton distributions (transversity GPDs) in the large-Nc limit of QCD. In contrast to the chiral-even case, only three combinations of the four chiral-odd GPDs are nonzero in the leading order of the 1 /Nc expansion: E¯T=ET+2 H˜T,HT , and E˜T. The degeneracy is explained by the absence of spin-orbit interactions correlating the transverse momentum transfer with the transverse quark spin. It can also be deduced from the natural Nc scaling of the quark-nucleon helicity amplitudes associated with the GPDs. In the GPD E¯T the flavor-singlet component u +d is leading in the 1 /Nc expansion, while in HT and E˜T it is the flavor-nonsinglet components u -d . The large-Nc relations are consistent with the spin-flavor structure extracted from hard exclusive π0 and η electroproduction data, if it is assumed that the processes are mediated by twist-3 amplitudes involving the chiral-odd GPDs and the chiral-odd pseudoscalar meson distribution amplitudes.

  2. Parton distributions incorporating QED contributions

    CERN Document Server

    Martin, A D; Stirling, W J; Thorne, R S

    2004-01-01

    We perform a global parton analysis of deep inelastic and related hard-scattering data, including ${\\cal O}(\\alpha_{\\rm QED})$ corrections to the parton evolution. Although the quality of the fit is essentially unchanged, there are two important physical consequences. First, the different DGLAP evolution of u and d type quarks introduces isospin violation, i.e. $u^p \

  3. Compton scattering and nonforward parton distributions

    CERN Document Server

    Radyushkin, A V

    1998-01-01

    The hard exclusive electroproduction processes provide new information about hadronic structure accumulated in nonforward parton distributions. The NFPD's are universal hybrid functions having the properties of parton densities, hadronic form factors and distribution amplitudes. They give a unified description of various hard exclusive and inclusive reactions. The basic supplier of information about nonforward parton distributions is deeply virtual Compton scattering which offers a remarkable example of Bjorken scaling phenomena in exclusive processes. Wide-angle real Compton scattering is an ideal tool to test angle-dependent scaling laws characteristic for soft overlap mechanism. Hard meson electroproduction is the best candidate to see pQCD hard gluon exchange in exclusive reactions.

  4. Modeling nuclear parton distribution functions

    CERN Document Server

    Honkanen, H; Guzey, V

    2013-01-01

    The presence of nuclear medium and collective phenomena which involve several nucleons modify the parton distribution functions of nuclei (nPDFs) compared to those of a free nucleon. These modifications have been investigated by different groups using global analyses of high energy nuclear reaction world data resulting in modern nPDF parametrizations with error estimates, such as EPS09(s), HKN07 and nDS. These phenomenological nPDF sets roughly agree within their uncertainty bands, but have antiquarks for large-$x$ and gluons for the whole $x$-range poorly constrained by the available data. In the kinematics accessible at the LHC this has negative impact on the interpretation of the heavy-ion collision data, especially for the $p + A$ benchmarking runs. The EMC region is also sensitive to the proper definition of $x$, where the nuclear binding effects have to be taken into account, and for heavy nuclei one also needs to take into account that a fraction of the nucleus momentum is carried by the equivalent pho...

  5. The generalized parton distribution function (E^u+E^d)(x,xi,t) of the nucleon in the chiral quark soliton model

    CERN Document Server

    Ossmann, J; Schweitzer, P; Urbano, D; Göke, K

    2004-01-01

    The unpolarized spin-flip isoscalar generalized parton distribution function (E^u+E^d)(x,xi,t) is studied in the large-Nc limit at a low normalization point in the framework of the chiral quark-soliton model. This is the first study of generalized parton distribution functions in this model, which appear only at the subleading order in the large-Nc limit. Particular emphasis is put therefore on the demonstration of the theoretical consistency of the approach. The forward limit of (E^u+E^d)(x,xi,t) of which only the first moment -- the anomalous isoscalar magnetic moment of the nucleon -- is known phenomenologically, is computed numerically. Observables sensitive to (E^u+E^d)(x,xi,t) are discussed.

  6. Nucleon form factors and moments of generalized parton distributions using N{sub f}= 2+1+1 twisted mass fermions

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, C. [Univ. of Cyprus, Nicosia (Cyprus). Dept. of Physics; Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Constantinou, M.; Kallidonis, C. [Univ. of Cyprus, Nicosia (Cyprus). Dept. of Physics; Dinter, S.; Drach, V. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Jansen, K. [Univ. of Cyprus, Nicosia (Cyprus). Dept. of Physics; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Koutsou, G. [Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Collaboration: European Twisted Mass Collaboration

    2013-04-15

    We present results on the axial and the electromagnetic form factors of the nucleon, as well as, on the first moments of the nucleon generalized parton distributions using maximally twisted mass fermions. We analyze two N{sub f}=2+1+1 ensembles having pion masses of 210 MeV and 354 MeV at two values of the lattice spacing. The lattice scale is determined using the nucleon mass computed on a total of 18 N{sub f}=2+1+1 ensembles generated at three values of the lattice spacing, a. The renormalization constants are evaluated non-perturbatively with a perturbative subtraction of O(a''2)-terms. The moments of the generalized parton distributions are given in the MS scheme at a scale of {mu}=2 GeV. We compare with recent results obtained using different discretization schemes. The implications on the spin content of the nucleon are also discussed.

  7. QCD collinear factorization, its extensions and the partonic distributions

    CERN Document Server

    Szymanowski, Lech

    2012-01-01

    I review the basics of the collinear factorization theorem applied primarily to deep inelastic scattering (DIS) involving forward parton distributions (PDFs) and the extensions of this theorem for exclusive processes probing non-forward parton distributions (GPDs), the generalized distribution amplitudes (GDAs) and the transition distribution amplitudes (TDAs). These QCD factorization theorem is an important tool in the description of hard processes in QCD. Whenever valid, it permits to represent the cross section or the scattering amplitude for such a process as a convolution in partonic momenta of a perturbatively calculable part (the coefficient function, CF) which involves the hard scale of the process with non-perturbative (soft) distributions of active partons inside the hadrons involved in a process. The reliability of the perturbatively determined hard part together with high precision experimental data on relevant observables gives a hope for the possibility to uncover fine details of interpartonic i...

  8. Unbiased spin-dependent Parton Distribution Functions

    CERN Document Server

    Nocera, Emanuele Roberto

    2014-01-01

    We present the first unbiased determination of spin-dependent, or polarized, Parton Distribution Functions (PDFs) of the proton. A statistically sound representation of the corresponding uncertainties is achieved by means of the NNPDF methodology: this was formerly developed for unpolarized distributions and is now generalized to the polarized here for the first time. The features of the procedure, based on robust statistical tools (Monte Carlo sampling for error propagation, neural networks for PDF parametrization, genetic algorithm for their minimization, and possibly reweighting for including new data samples without refitting), are illustrated in detail. Different sets of polarized PDFs are obtained at next-to-leading order accuracy in perturbative quantum chromodynamics, based on both fixed-target inclusive deeply-inelastic scattering data and the most recent polarized collider data. A quantitative appraisal on the potential role of future measurements at an Electron-Ion Collider is also presented. We st...

  9. Parton Momentum Distribution at the Moment of Jet-Parton Collisions

    Institute of Scientific and Technical Information of China (English)

    WONG Cheuk-Yin

    2008-01-01

    The early parton momentum distribution is extracted by using the STAR collaboration data of ridge particles associated with a near-side jet in central AuAu collisions at (√SNN)= 200 GeV. The ridge particles are identified as medium partons kicked by the jet near the surface and they carry direct information on the parton momentum distribution at the moment of jet-parton collisions. The extracted parton momentum distribution has a thermal-like transverse momentum distribution but a rapidity plateau structure with a relatively fiat rapidity distribution at mid-rapidities with sharp kinematic boundaries at large rapidities that depend on the transverse momentum.

  10. Positivity bounds on double parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus; Kasemets, Tomas

    2013-03-15

    Double hard scattering in proton-proton collisions is described in terms of double parton distributions. We derive bounds on these distributions that follow from their interpretation as probability densities, taking into account all possible spin correlations between two partons in an unpolarized proton. These bounds constrain the size of the polarized distributions and can for instance be used to set upper limits on the effects of spin correlations in double hard scattering. We show that the bounds are stable under leading-order DGLAP evolution to higher scales.

  11. The parton distribution function library

    Energy Technology Data Exchange (ETDEWEB)

    Plothow-Besch, H. [Universitat Dortmund (Germany)

    1995-07-01

    This article describes an integrated package of Parton Density Functions called PDFLIB which has been added to the CERN Program Library Pool W999 and is labelled as W5051. In this package all the different sets of parton density functions of the Nucleon, Pion and the Photon which are available today have been put together. All these sets have been combined in a consistent way such that they all have similar calling sequences and no external data files have to be read in anymore. A default set has been prepared, although those preferring their own set or wanting to test a new one may do so within the package. The package also offers a program to calculate the strong coupling constant {alpha}, to first or second order. The correct {Lambda}{sub QCD} associated to the selected set of structure functions and the number of allowed flavours with respect to the given Q{sup 2} is automatically used in the calculation. The selection of sets, the program parameters as well as the possibilities to modify the defaults and to control errors occurred during execution are described.

  12. Nuclear modifications of Parton Distribution Functions

    Science.gov (United States)

    Adeluyi, Adeola Adeleke

    This dissertation addresses a central question of modern nuclear physics: how does the behavior of fundamental degrees of freedom (quarks and gluons) change in the nuclear environment? This is an important aspect of experimental studies at current facilities such as the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Laboratory (JLAB). It is also highly relevant to planned experimental efforts at the Large Hadron Collider (LHC) and the future Electron Ion Collider (EIC). All these facilities probe matter via collisions involving nuclei; thus complications arise due to the presence of the attendant nuclear medium. Theoretical efforts to understand and interpret experimental results from such collisions are therefore largely dependent on the resolution of this question. The development of nuclear physics demonstrates that theoretical description is most efficient in terms of the effective degrees of freedom relevant to the scale (energy) being probed. Thus at low energies, nuclei are described as bound states of protons and neutrons (nucleons). At higher energies, the nucleons are no longer elementary, but are revealed to possess an underlying substructure: they are made up of quarks and gluons, collectively termed partons. The mometum distributions of these partons in the nucleon are referred to as Parton Distribution Functions (PDFs). Parton distributions can be determined from experimental measurements of structure functions. The ratio of nuclear structure functions to nucleon structure functions (generically referred to as nuclear ratio) is a measure of the nuclear modifications of the free nucleon PDFs. Thus a study of the nuclear ratio suffices to gain an understanding of nuclear modifications. In this dissertation we aim to describe theoretically nuclear modifications in a restricted region where the nuclear ratio is less than unity, the so

  13. Hard gluon evolution of nucleon generalized parton distributions in the light-front quark model. Hard gluon evolution of nucleon GPDs

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Neetika [Indian Institute of Science Education and Research Mohali, Mohali (India)

    2016-04-15

    We incorporate the perturbative evolution effects in the generalized parton distributions (GPDs) calculated in effective light-front quark model for the nucleon. The perturbative effects enter into formalism through the evolution of GPDs according to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-like (DGLAP) equation. We obtain the evolved GPDs in the momentum space and transverse impact parameter space. We observe that combining the light-front quark model with the perturbative evolution effects, give the effective model for studying the phenomenological GPDs. (orig.)

  14. Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the nucleon with the CLAS and CLAS12 detectors at the Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Guegan, Baptiste [Rensselaer Polytechnic Inst., Troy, NY (United States)

    2012-11-01

    The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN {yields} lN{gamma} , and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.

  15. Parton distribution functions with QED corrections

    CERN Document Server

    Carrazza, Stefano

    2015-01-01

    We present the first unbiased determination of parton distribution functions (PDFs) with electroweak corrections. The aim of this thesis is to provide an exhaustive description of the theoretical framework and the technical implementation which leads to the determination of a set of PDFs which includes the photon PDF and quantum electrodynamics (QED) contributions to parton evolution. First, we introduce and motivate the need of including electroweak corrections to PDFs, providing phenomenological examples and presenting an overview of the current state of the art in PDF fits. The theoretical implications of such corrections are then described through the implementation of the combined QCD+QED evolution in APFEL, a public code for the solution of the PDF evolution developed particularly for this thesis. We proceed by presenting the new structure of the Neural-Network PDF (NNPDF) methodology used for the extraction of this set of PDFs with QED corrections. We then provide a first determination of the full set ...

  16. New Lattice Results for Parton Distributions

    CERN Document Server

    Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian

    2016-01-01

    We provide a high statistics analysis of the $x$-dependence of the bare unpolarized, helicity and transversity iso-vector parton distribution functions (PDFs) from lattice calculations employing (maximally) twisted mass fermions. The $x$-dependence of the calculated PDFs resembles those of the phenomenological parameterizations, a feature that makes this approach promising despite the lack of a full renormalization program for them. Furthermore, we apply momentum smearing for the relevant matrix elements to compute the lattice PDFs and find a large improvement factor when compared to conventional Gaussian smearing. This allows us to extend the lattice computation of the distributions to higher values of the nucleon momentum.

  17. Applications of KP Nuclear Parton Distributions

    CERN Document Server

    Kulagin, Sergey

    2016-01-01

    We review the nuclear parton distribution functions computed on the basis of our microscopic model taking into account a number of nuclear effects including Fermi motion and nuclear binding, nuclear meson-exchange currents, off-shell corrections to bound nucleon distributions and nuclear shadowing. We discuss applications to a number of different processes including lepton-nucleus deep inelastic scattering, proton-nucleus Drell-Yan lepton pair production at Fermilab, as well as $W^\\pm$ and $Z^0$ boson production in proton-lead collisions at the LHC.

  18. A Lattice Calculation of Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, Constantia [Cyprus Univ. Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus); Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins; Univ. of Southern Denmark, Odense (Denmark). Danish IAS; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Hadjiyiannakou, Kyriakos [Cyprus Univ. Nicosia (Cyprus). Dept. of Physics; Jansen, Karl; Steffens, Fernanda; Wiese, Christian [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2015-04-15

    We report on our exploratory study for the direct evaluation of the parton distribution functions from lattice QCD, based on a recently proposed new approach. We present encouraging results using N{sub f}=2+1+1 twisted mass fermions with a pion mass of about 370 MeV. The focus of this work is a detailed description of the computation, including the lattice calculation, the matching to an infinite momentum and the nucleon mass correction. In addition, we test the effect of gauge link smearing in the operator to estimate the influence of the Wilson line renormalization, which is yet to be done.

  19. A Lattice Calculation of Parton Distributions

    CERN Document Server

    Alexandrou, Constantia; Drach, Vincent; Garcia-Ramos, Elena; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian

    2015-01-01

    We report on our exploratory study for the direct evaluation of the parton distribution functions from lattice QCD, based on a recently proposed new approach. We present encouraging results using Nf = 2 + 1 + 1 twisted mass fermions with a pion mass of about 370 MeV. The focus of this work is a detailed description of the computation, including the lattice calculation, the matching to an infinite momentum and the nucleon mass correction. In addition, we test the effect of gauge link smearing in the operator to estimate the influence of the Wilson line renormalization, which is yet to be done.

  20. ABM11 parton distributions and benchmarks

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, Sergey [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation); Bluemlein, Johannes; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2012-08-15

    We present a determination of the nucleon parton distribution functions (PDFs) and of the strong coupling constant {alpha}{sub s} at next-to-next-to-leading order (NNLO) in QCD based on the world data for deep-inelastic scattering and the fixed-target data for the Drell-Yan process. The analysis is performed in the fixed-flavor number scheme for n{sub f}=3,4,5 and uses the MS scheme for {alpha}{sub s} and the heavy quark masses. The fit results are compared with other PDFs and used to compute the benchmark cross sections at hadron colliders to the NNLO accuracy.

  1. Pion valence-quark parton distribution function

    Directory of Open Access Journals (Sweden)

    Lei Chang

    2015-10-01

    Full Text Available Within the Dyson–Schwinger equation formulation of QCD, a rainbow ladder truncation is used to calculate the pion valence-quark distribution function (PDF. The gap equation is renormalized at a typical hadronic scale, of order 0.5 GeV, which is also set as the default initial scale for the pion PDF. We implement a corrected leading-order expression for the PDF which ensures that the valence-quarks carry all of the pion's light-front momentum at the initial scale. The scaling behavior of the pion PDF at a typical partonic scale of order 5.2 GeV is found to be (1−xν, with ν≃1.6, as x approaches one.

  2. Insights into nucleon structure from parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Melnitchouk, Wally [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2017-05-01

    We review recent progress in understanding the substructure of the nucleon from global QCD analysis of parton distribution functions (PDFs). New high-precision data onW-boson production in p ¯ p collisions have significantly reduced the uncertainty on the d=u PDF ratio at large values of x, indirectly constraining models of the medium modification of bound nucleons. Drell-Yan data from pp and pd scattering reveal new information on the d¯-u¯ asymmetry, clarifying the role of chiral symmetry breaking in the nucleon. In the strange sector, a new chiral SU(3) analysis finds a valence-like component of the strange-quark PDF, giving rise to a nontrivial s- ¯ s asymmetry at moderate x values. We also review recent analyses of charm in the nucleon, which have found conflicting indications of the size of the nonperturbative charm component.

  3. Dynamical parton distributions from DGLAP equations with nonlinear corrections

    CERN Document Server

    Wang, Rong

    2016-01-01

    Determination of proton parton distribution functions is present under the dynamical parton model assumption by applying DGLAP equations with GLR-MQ-ZRS corrections. We provide two data sets, referred as IMParton16, which are from two different nonperturbative inputs. One is the naive three valence quarks input and the other is three valence quarks with flavor-asymmetric sea components input. Basically, both data sets are compatible with the experimental measurements at high scale ($Q^2>2$ GeV$^2$). Furthermore, our analysis shows that the input with flavor-asymmetric sea components better reproduce the structure functions at high $Q^2$. Generally, the obtained parton distribution functions, especially the gluon distribution functions, are the good options of inputs for simulations of high energy scattering processes. The analysis is performed under the fixed-flavor number scheme for $n_f=$ 3, 4, 5 and uses the $\\overline{\\text MS}$ scheme for the running coupling $\\alpha_s$ and the heavy-quark masses. Both d...

  4. Parton distributions for the LHC Run II

    CERN Document Server

    Ball, Richard D.; Carrazza, Stefano; Deans, Christopher S.; Del Debbio, Luigi; Forte, Stefano; Guffanti, Alberto; Hartland, Nathan P.; Latorre, José I.; Rojo, Juan; Ubiali, Maria

    2015-01-01

    We present NNPDF3.0, the first set of parton distribution functions (PDFs) determined with a methodology validated by a closure test. NNPDF3.0 uses a global dataset including HERA-II deep-inelastic inclusive cross-sections, the combined HERA charm data, jet production from ATLAS and CMS, vector boson rapidity and transverse momentum distributions from ATLAS, CMS and LHCb, W+c data from CMS and top quark pair production total cross sections from ATLAS and CMS. Results are based on LO, NLO and NNLO QCD theory and also include electroweak corrections. To validate our methodology, we show that PDFs determined from pseudo-data generated from a known underlying law correctly reproduce the statistical distributions expected on the basis of the assumed experimental uncertainties. This closure test ensures that our methodological uncertainties are negligible in comparison to the generic theoretical and experimental uncertainties of PDF determination. This enables us to determine with confidence PDFs at different pertu...

  5. Improved quasi parton distribution through Wilson line renormalization

    CERN Document Server

    Chen, Jiunn-Wei; Zhang, Jian-Hui

    2016-01-01

    Recent developments showed that hadron light-cone parton distributions could be directly extracted from spacelike correlators, known as quasi parton distributions, in the large hadron momentum limit. Unlike the normal light-cone parton distribution, a quasi parton distribution contains ultraviolet (UV) power divergence associated with the Wilson line self energy. We show that to all orders in the coupling expansion, the power divergence can be removed by a "mass" counterterm in the auxiliary $z$-field formalism, in the same way as the renormalization of power divergence for an open Wilson line. After adding this counterterm, the quasi quark distribution is improved such that it contains at most logarithmic divergences. Based on a simple version of discretized gauge action, we present the one-loop matching kernel between the improved non-singlet quasi quark distribution with a lattice regulator and the corresponding quark distribution in dimensional regularization.

  6. Improved quasi parton distribution through Wilson line renormalization

    Directory of Open Access Journals (Sweden)

    Jiunn-Wei Chen

    2017-02-01

    Full Text Available Recent developments showed that hadron light-cone parton distributions could be directly extracted from spacelike correlators, known as quasi parton distributions, in the large hadron momentum limit. Unlike the normal light-cone parton distribution, a quasi parton distribution contains ultraviolet (UV power divergence associated with the Wilson line self energy. We show that to all orders in the coupling expansion, the power divergence can be removed by a “mass” counterterm in the auxiliary z-field formalism, in the same way as the renormalization of power divergence for an open Wilson line. After adding this counterterm, the quasi quark distribution is improved such that it contains at most logarithmic divergences. Based on a simple version of discretized gauge action, we present the one-loop matching kernel between the improved non-singlet quasi quark distribution with a lattice regulator and the corresponding quark distribution in dimensional regularization.

  7. Parton Distributions of Pions in the Valon Model

    Institute of Scientific and Technical Information of China (English)

    杨纯斌

    2003-01-01

    Based on the universality of the parton distributions inside valons, parton distributions of pions are investigated and parametrized from the experimentally given parton distributions of proton within the valon model The structure function F2(x) is given at fixed scale Q20 = 1 GeV2. Due to the abundance of the pair numbers of sea quarks at a very small x region, the structure function decreases rapidly for small x to a local minimum. Then from the contribution of the valence quarks, F2(x) increases to a local maximum at x (∽-)0.5.

  8. Parton distributions: HERA-Tevatron-LHC

    CERN Document Server

    Watt, Graeme

    2009-01-01

    The parton distribution functions (PDFs) are a non-negotiable input to almost all theory predictions at hadron colliders. In this talk, I introduce PDF determination by global analysis and discuss selected topics concerning recent relevant data from HERA and the Tevatron, before giving some prospects for the LHC. The combination of H1 and ZEUS cross sections reduces uncertainties and will be an important input to future global PDF analyses. The theoretical description of the heavy-quark contribution to structure functions at HERA has a significant influence on predictions at the LHC. New W and Z data from the Tevatron Run II provide important PDF constraints, but there are currently problems describing the latest data on the lepton charge asymmetry from W -> l nu decays. The Tevatron Run II jet production data prefer a smaller high-x gluon than the previous Run I data, which impacts on predictions for Higgs cross sections at the Tevatron. It is now possible to consistently calculate a combined "PDF+alpha_S" u...

  9. Nucleon parton distributions in a light-front quark model

    Energy Technology Data Exchange (ETDEWEB)

    Gutsche, Thomas [Universitaet Tuebingen, Institut fuer Theoretische Physik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Lyubovitskij, Valery E. [Universitaet Tuebingen, Institut fuer Theoretische Physik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Tomsk Polytechnic University, Laboratory of Particle Physics, Mathematical Physics Department, Tomsk (Russian Federation); Universidad Tecnica Federico Santa Maria, Departamento de Fisica y Centro Cientifico Tecnologico de Valparaiso (CCTVal), Valparaiso (Chile); Schmidt, Ivan [Universidad Tecnica Federico Santa Maria, Departamento de Fisica y Centro Cientifico Tecnologico de Valparaiso (CCTVal), Valparaiso (Chile)

    2017-02-15

    Continuing our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity-independent and the helicity-dependent parton distributions, analytically matching the results of global fits at the initial scale μ∝ 1 GeV; they also contain the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution. We also calculate the transverse parton, Wigner and Husimi distributions from a unified point of view, using our light-front wave functions and expressing them in terms of the parton distributions q{sub v}(x) and δq{sub v}(x). Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN). (orig.)

  10. Nucleon parton distributions in a light-front quark model

    CERN Document Server

    Gutsche, Thomas; Schmidt, Ivan

    2016-01-01

    Continuing with our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity independent and helicity dependent parton distributions, analytically matching the results of global fits at the initial scale $\\mu \\sim 1$ GeV, and which also contain the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution. We also calculate the transverse parton, Wigner and Husimi distributions from a unified point of view, using our light-front wave functions and expressing them in terms of the parton distributions $q_v(x)$ and $\\delta q_v(x)$. Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN).

  11. Nuclear parton distributions and the Drell-Yan process

    Science.gov (United States)

    Kulagin, S. A.; Petti, R.

    2014-10-01

    We study the nuclear parton distribution functions on the basis of our recently developed semimicroscopic model, which takes into account a number of nuclear effects including nuclear shadowing, Fermi motion and nuclear binding, nuclear meson-exchange currents, and off-shell corrections to bound nucleon distributions. We discuss in detail the dependencies of nuclear effects on the type of parton distribution (nuclear sea vs valence), as well as on the parton flavor (isospin). We apply the resulting nuclear parton distributions to calculate ratios of cross sections for proton-induced Drell-Yan production off different nuclear targets. We obtain a good agreement on the magnitude, target and projectile x, and the dimuon mass dependence of proton-nucleus Drell-Yan process data from the E772 and E866 experiments at Fermilab. We also provide nuclear corrections for the Drell-Yan data from the E605 experiment.

  12. Nuclear Parton Distributions and the Drell-Yan Process

    CERN Document Server

    Kulagin, S A

    2014-01-01

    We study the nuclear parton distribution functions basing on our recently developed semi-microscopic model, which takes into account a number of nuclear effects including nuclear shadowing, Fermi motion and nuclear binding, nuclear meson-exchange currents and off-shell corrections to bound nucleon distributions. We discuss in details the dependencies of nuclear effects on the type of parton distribution (nuclear sea vs. valence) as well as on the parton flavour (isospin). The resulting nuclear parton distributions are applied to calculate the ratios of cross sections for proton-induced Drell-Yan production off different nuclear targets. We obtain a good agreement on the magnitude, target and projectile x and the dimuon mass dependence of proton-nucleus Drell-Yan process data from the E772 and E866 experiments at Fermilab.

  13. Sketching the pion's valence-quark generalised parton distribution

    Directory of Open Access Journals (Sweden)

    C. Mezrag

    2015-02-01

    Full Text Available In order to learn effectively from measurements of generalised parton distributions (GPDs, it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL truncation of QCD's Dyson–Schwinger equations and exemplified via the pion's valence dressed-quark GPD, Hπv(x,ξ,t. Our analysis focuses primarily on ξ=0, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting Hπv(x,ξ=±1,t with the pion's valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to define the pion's valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for Hπv(x,0,t, expressed as the Radon transform of a single amplitude. Therewith we obtain results for Hπv(x,0,t and the associated impact-parameter dependent distribution, qπv(x,|b→⊥|, which provide a qualitatively sound picture of the pion's dressed-quark structure at a hadronic scale. We evolve the distributions to a scale ζ=2 GeV, so as to facilitate comparisons in future with results from experiment or other nonperturbative methods.

  14. Experimental Tests of Charge Symmetry Violation in Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    J.T. Londergan; D.P. Murdock; A.W. Thomas

    2005-07-01

    Recently, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the allowed magnitude of such effects. We discuss two possible experiments that could search for isospin violation in valence parton distributions. We show that, given the magnitude of charge symmetry violation consistent with existing global data, such experiments might expect to see effects at a level of several percent. Alternatively, such experiments could significantly decrease the upper limits on isospin violation in parton distributions.

  15. Overview of parton distributions and the quantum chromodynamics (QCD) framework

    Energy Technology Data Exchange (ETDEWEB)

    Tuni, Wu-Ki (Institute of Gas Technology, Chicago, IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))

    1990-08-01

    The perturbative QCD framework as the basis of the parton model is reviewed with emphasis on several issues pertinent to next-to-leading order (NLO) applications to a wide range of high energy processes. The current status of leading-order and NLO parton distributions is summarized and evaluated. Relevant issues and open questions for second-generation global analyses are discussed in order to provide an overview of topics to be covered by the Workshop. 15 refs., 6 figs., 1 tabs.

  16. Sketching the pion's valence-quark generalised parton distribution

    CERN Document Server

    Mezrag, C; Moutarde, H; Roberts, C D; Rodriguez-Quintero, J; Sabatie, F; Schmidt, S M

    2014-01-01

    In order to learn effectively from measurements of generalised parton distributions (GPDs), it is desirable to compute them using a framework that can potentially connect empirical information with basic features of the Standard Model. We sketch an approach to such computations, based upon a rainbow-ladder (RL) truncation of QCD's Dyson-Schwinger equations and exemplified via the pion's valence dressed-quark GPD, $H_\\pi^{\\rm v}(x,\\xi,t)$. Our analysis focuses primarily on $\\xi=0$, although we also capitalise on the symmetry-preserving nature of the RL truncation by connecting $H_\\pi^{\\rm v}(x,\\xi=\\pm 1,t)$ with the pion's valence-quark parton distribution amplitude. We explain that the impulse-approximation used hitherto to define the pion's valence dressed-quark GPD is generally invalid owing to omission of contributions from the gluons which bind dressed-quarks into the pion. A simple correction enables us to identify a practicable improvement to the approximation for $H_\\pi^{\\rm v}(x,0,t)$, expressed as th...

  17. New results in the quantum statistical approach to parton distributions

    CERN Document Server

    Soffer, Jacques; Bourrely, Claude

    2014-01-01

    We will describe the quantum statistical approach to parton distributions allowing to obtain simultaneously the unpolarized distributions and the helicity distributions. We will present some recent results, in particular related to the nucleon spin structure in QCD. Future measurements are challenging to check the validity of this novel physical framework.

  18. New advances in the statistical parton distributions approach*

    Directory of Open Access Journals (Sweden)

    Soffer Jacques

    2016-01-01

    Full Text Available The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in terms of a rather small number of free parameters. There are many serious challenging issues. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in W± production in p̄p and pp collisions up to LHC energies, using recent data and also for forthcoming experimental results.

  19. Impact Parameter Dependent Parton Distributions for a Composite Relativistic System

    CERN Document Server

    Chakraborty, D

    2004-01-01

    We investigate the impact parameter dependent parton distributions for a relativistic composite system in light-front framework. We take an effective two-body spin-1/2 state, namely an electron dressed with a photon in QED. We express the impact parameter dependent parton distributions in terms of overlaps of light-cone wave functions. We obtain the scale dependence of both fermion and gauge boson distributions and show the distortion of the pdfs in the transverse space for transverse polarization of the state at one loop level.

  20. Nucleon Helicity and Transversity Parton Distributions from Lattice QCD

    CERN Document Server

    Chen, Jiunn-Wei; Ji, Xiangdong; Lin, Huey-Wen; Zhang, Jian-Hui

    2016-01-01

    We present the first lattice-QCD calculation of the isovector polarized parton distribution functions (both helicity and transversity) using the large-momentum effective field theory (LaMET) approach for direct Bjorken-$x$ dependence. We first review the detailed steps of the procedure in the unpolarized case, then generalize to the helicity and transversity cases. We also derive a new mass-correction formulation for all three cases. We then compare the effects of each finite-momentum correction using lattice data calculated at $M_\\pi\\approx 310$ MeV. Finally, we discuss the implications of these results for the poorly known antiquark structure and predict the sea-flavor asymmetry in the transversely polarized nucleon.

  1. The role of the input scale in parton distribution analyses

    CERN Document Server

    Jimenez-Delgado, Pedro

    2012-01-01

    A first systematic study of the effects of the choice of the input scale in global determinations of parton distributions and QCD parameters is presented. It is shown that, although in principle the results should not depend on these choices, in practice a relevant dependence develops as a consequence of what is called procedural bias. This uncertainty should be considered in addition to other theoretical and experimental errors, and a practical procedure for its estimation is proposed. Possible sources of mistakes in the determination of QCD parameter from parton distribution analysis are pointed out.

  2. Transverse-momentum-dependent parton distribution/fragmentation functions at an electron-ion collider

    NARCIS (Netherlands)

    Anselmino, M.; Avakian, H.; Boer, Daniël; Bradamante, F.; Burkardt, M.; Chen, J.P.; Cisbani, E.; Contalbrigo, M.; Crabb, D.; Dutta, D.; Gamberg, L.; Gao, H.; Hasch, D.; Huang, J.; Huang, M.; Kang, Z.; Keppel, C.; Laskaris, G.; Liang, Z.-T.; Liu, M.X.; Makins, N.; McKeown, R.D.; Metz, A.; Meziani, Z.-E.; Musch, B.; Peng, J.-C.; Prokudin, A.; Qian, X.; Qiang, Y.; Qiu, J.W.; Rossi, P.; SCHWEITZER, C.; Soffer, J.; Sulkosky, V.; Wang, Ying; Xiao, B.; Ye, Q.; Ye, Q.-J.; Yuan, F.; Zhan, X.; Zhang, Y.; Zheng, W.; Zhou, J.

    2011-01-01

    We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse-momentum-dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton

  3. Parton distribution functions in Monte Carlo factorisation scheme

    Science.gov (United States)

    Jadach, S.; Płaczek, W.; Sapeta, S.; Siódmok, A.; Skrzypek, M.

    2016-12-01

    A next step in development of the KrkNLO method of including complete NLO QCD corrections to hard processes in a LO parton-shower Monte Carlo is presented. It consists of a generalisation of the method, previously used for the Drell-Yan process, to Higgs-boson production. This extension is accompanied with the complete description of parton distribution functions in a dedicated, Monte Carlo factorisation scheme, applicable to any process of production of one or more colour-neutral particles in hadron-hadron collisions.

  4. Relativistic effects in model calculations of double parton distribution function

    CERN Document Server

    Rinaldi, Matteo

    2016-01-01

    In this paper we consider double parton distribution functions (dPDFs) which are the main non perturbative ingredients appearing in the double parton scattering cross section formula in hadronic collisions. By using recent calculation of dPDFs by means of constituent quark models within the so called Light-Front approach, we investigate the role of relativistic effects on dPDFs. We find, in particular, that the so called Melosh operators, which allow to properly convert the LF spin into the canonical one and incorporate a proper treatment of boosts, produce sizeable effects on dPDFs. We discuss specific partonic correlations induced by these operators in transverse plane which are relevant to the proton structure and study under which conditions these results are stable against variations in the choice of the proton wave function.

  5. Double parton distributions in Light-Front constituent quark models

    CERN Document Server

    Rinaldi, Matteo; Traini, Marco; Vento, Vicente

    2014-01-01

    Double parton distribution functions (dPDF), accessible in high energy proton-proton and proton nucleus collisions, encode information on how partons inside a proton are correlated among each other and could represent a tool to explore the 3D proton structure. In recent papers, double parton correlations have been studied in the valence quark region, by means of constituent quark models. This framework allows to understand clearly the dynamical origin of the correlations and to establish which, among the features of the results, are model independent. Recent relevant results, obtained in a relativistic light-front scheme, able to overcome some drawbacks of previous calculations, such as the poor support, will be presented. Peculiar transverse momentum correlations, generated by the correct treatment of the boosts, are obtained. The role of spin correlations will be also shown. In this covariant approach, the symmetries of the dPDFs are unambiguously reproduced. The study of the QCD evolution of the model resu...

  6. The QCD coupling and parton distributions at high precision

    Energy Technology Data Exchange (ETDEWEB)

    Bluemlein, Johannes

    2010-07-15

    A survey is given on the present status of the nucleon parton distributions and related precision calculations and precision measurements of the strong coupling constant {alpha}{sub s}(M{sup 2}{sub Z}). We also discuss the impact of these quantities on precision observables at hadron colliders. (orig.)

  7. Parton distributions and{alpha}{sub s} for the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation); Bluemlein, J. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Moch, S.O. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Univ. Hamburg (Germany). 2. Inst fuer Theoretische Physik

    2013-03-15

    We report on recent determinations of NNLO parton distributions and of {alpha}{sub s}(M{sub Z}) based on the world deep-inelastic data, supplemented by collider data. Some applications are discussed for semi-inclusive processes at the LHC.

  8. Conformal string operators and evolution of skewed parton distributions

    CERN Document Server

    Kivel, N A

    1999-01-01

    We have investigated skewed parton distributions in coordinate space. We found that their evolution can be described in a simple manner in terms of non-local, conformal operators introduced by Balitsky and Braun. The resulting formula is given by a Neumann series expansion. Its structure resembles, for all values of the asymmetry parameter, the well-known solution of the ERBL equation in the momentum space. Performing Fourier transformation we have reproduced known results for evolution of momentum-space distributions.

  9. Global study of nuclear modifications on parton distribution functions

    CERN Document Server

    Wang, Rong; Fu, Qiang

    2016-01-01

    A global analysis of nuclear medium modifications of parton distributions is presented using deeply inelastic scattering data of various nuclear targets. Two obtained data sets are provided for quark and gluon nuclear modification factors, referred as nIMParton16. One is from the global fit only to the experimental data of isospin-scalar nuclei (Set A), and the other is from the fit to all the measured nuclear data (Set B). The scale-dependence is described by DGLAP equations with nonlinear corrections in this work. The Fermi motion and off-shell effect, nucleon swelling, and parton-parton recombination are taken into account together for modeling the complicated $x$-dependence of nuclear modification. The nuclear gluon shadowing in this paper is dynamically generated by the QCD evolution of parton splitting and recombination processes with zero gluon density at the input scale. Sophisticated nuclear dependence of nuclear medium effects is studied with only two free parameters. With the obtained free paramete...

  10. A Lattice Calculation of Parton Distributions

    CERN Document Server

    Alexandrou, Constantia; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian

    2016-01-01

    We present results for the $x$ dependence of the unpolarized, helicity, and transversity isovector quark distributions in the proton using lattice QCD, employing the method of quasi-distributions proposed by Ji in 2013. Compared to a previous calculation by us, the errors are reduced by a factor of about 2.5. Moreover, we present our first results for the polarized sector of the proton, which indicate an asymmetry in the proton sea in favor of the $u$ antiquarks for the case of helicity distributions, and an asymmetry in favor of the $d$ antiquarks for the case of transversity distributions.

  11. A lattice calculation of parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus); Cichy, Krzysztof [Frankfurt Univ. (Germany). Inst. fuer Theoretische Physik; Poznann Univ. (Poland). Faculty of Physics; Hadjiyiannakou, Kyriakos [George Washington Univ., Washington, DC (United States). Dept. of Physics; Jansen, Karl; Steffens, Fernanda; Wiese, Christian [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2016-09-15

    We present results for the x dependence of the unpolarized, helicity, and transversity isovector quark distributions in the proton using lattice QCD, employing the method of quasi-distributions proposed by Ji in 2013. Compared to a previous calculation by us, the errors are reduced by a factor of about 2.5. Moreover, we present our first results for the polarized sector of the proton, which indicate an asymmetry in the proton sea in favor of the u antiquarks for the case of helicity distributions, and an asymmetry in favor of the d antiquarks for the case of transversity distributions.

  12. Understanding Parton Distributions from Lattice QCD

    OpenAIRE

    Renner, Dru B.

    2005-01-01

    I examine the past lattice QCD calculations of three representative observables, the transverse quark distribution, momentum fraction, and axial charge, and emphasize the prospects for not only quantitative comparison with experiment but also qualitative understanding of QCD.

  13. Heavy-quark parton distribution functions and their uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Z. Sullivan and P.M. Nadolsky

    2001-12-07

    We investigate the uncertainties of the heavy-quark parton distribution functions in the variable avor number scheme. Because the charm- and bottom-quark parton distribution functions (PDFs) are constructed predominantly from the gluon PDF, it is a common practice to assume that the heavy-quark and gluon uncertainties are the same. We show that this approximation is a reasonable first guess, but it is better for bottom quarks than charm quarks. We calculate the PDF uncertainty for t-channel single-top-quark production using the Hessian matrix method, and predict a cross section of 2.12{sub -0.29}{sup +0.32} pb at run II of the Tevatron.

  14. Leading Twist Parton Distribution Amplitudes in Heavy Vector Mesons

    Directory of Open Access Journals (Sweden)

    Gao Fei

    2016-01-01

    Full Text Available We employed QCD’s Dyson-Schwinger equations (DSEs for heavy quarks and obtained the leading twist parton distribution amplitudes (PDAs in heavy vector mesons J/Ψ and ϒ. We found that all of the amplitudes are narrower than the asymptotic form, while they deviate from δ function. This indicates that the interaction between the two continent quarks are still important in the mesons consisted of charm and bottom quarks.

  15. Impact Parameter Dependent Parton Distributions for a Relativistic Composite System

    CERN Document Server

    Chakraborty, D

    2004-01-01

    We investigate the impact parameter dependent parton distributions for a relativistic composite system in light-front framework. We express them in terms of overlaps of light-cone wave functions for a self consistent two-body spin-1/2 state, namely an electron dressed with a photon in QED. The pdfs are distorted in the transverse space for transverse polarization of the state at one loop level.

  16. Exclusive η electroproduction at W>2 GeV with CLAS and transversity generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Bedlinskiy, I.; Kubarovsky, V.; Stoler, P.; Adhikari, K. P.; Akbar, Z.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Ciullo, G.; Clark, L.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D' Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Elouadrhiri, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Fersch, R.; Filippi, A.; Fleming, J. A.; Forest, T. A.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gleason, C.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Hughes, S. M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Khachatryan, M.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Kuhn, S. E.; Kuleshov, S. V.; Lanza, L.; Lenisa, P.; Livingston, K.; MacGregor, I. J. D.; Markov, N.; McKinnon, B.; Meziani, Z. E.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Net, L. A.; Ni, A.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Peng, P.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schumacher, R. A.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tian, Ye; Torayev, B.; Turisini, M.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Yurov, M.; Zachariou, N.; Zhang, J.; Zonta, I.

    2017-03-01

    The cross section of the exclusive eta electroproduction reaction ep -> e'p'eta was measured at Jefferson Laboratorywith a 5.75 GeV electron beam and the CLAS detector. Differential cross sections d(4) sigma/dtdQ(2) dx(B)d phi(eta) and structure functions sigma(U) = sigma(T) + epsilon sigma(L), sigma(TT), and sigma(LT), as functions of t, were obtained over a wide range of Q(2) and x(B). The eta structure functions are compared with those previously measured for pi(0) at the same kinematics. At low t, both pi(0) and eta are described reasonably well by generalized parton distributions (GPDs) in which chiral-odd transversity GPDs are dominant. The pi(0) and eta data, when taken together, can facilitate the flavor decomposition of the transversity GPDs.

  17. Selected topics on parton distribution functions

    CERN Document Server

    Hirai, M; Kumano, S; Saito, K

    2011-01-01

    We report recent studies on structure functions of the nucleon and nuclei. First, clustering effects are investigated in the structure function F_2 of Be-9 for explaining an unusual nuclear correction found in a JLab experiment. We propose that high densities created by formation of clustering structure like 2*alpha+neutron in Be-9 is the origin of the unexpected JLab result by using the antisymmetrized molecular dynamics (AMD). There is an approved proposal at JLab to investigate the structure functions of light nuclei including the cluster structure, so that much details will become clear in a few years. Second, tensor-polarized quark and antiquark distributions are obtained by analyzing HERMES measurements on the structure function b_1 for the deuteron. The result suggests a finite tensor polarization for antiquark distributions, which is an interesting topic for further theoretical and experimental investigations. An experimental proposal exists at JLab for measuring b_1 of the deuteron as a new tensor-st...

  18. Nuclear Parton Distributions with the LHeC

    Directory of Open Access Journals (Sweden)

    Klein Max

    2016-01-01

    Full Text Available Nuclear parton distributions are far from being known today because of an infant experimental base. Based on design studies of the LHeC and using new simulations, of the inclusive neutral and charged current cross section measurements and of the strange, charm and beauty densities in nuclei, it is demonstrated how that energy frontier electron-ion collider would unfold the complete set of nuclear PDFs in a hugely extended kinematic range of deep inelastic scattering, extending in Bjorken x down to values near to 10−6 in the perturbative domain. Together with a very precise and complete set of proton PDFs, the LHeC nPDFs will thoroughly change the theoretical understanding of parton dynamics and structure inside hadrons.

  19. Parton distributions for the pion in a chiral quark model

    CERN Document Server

    Ruiz-Arriola, E

    2001-01-01

    Parton distributions for the pion are studied in a chiral quark model characterized by a quark propagator for which a spectral representation is assumed. Electromagnetic and chiral symmetry constraints are imposed through the relevant Ward-Takahashi identities for flavoured vertex functions. Finiteness of the theory, requires the spectral function to be non-positive definite. Straightforward calculation yields the result that the pion structure function becomes one in the chiral limit, regardless of the details of the spectral function. LO and NLO evolution provide a satisfactory description of phenomenological parameterizations of the valence distribution functions but fails to describe gluon and sea distributions.

  20. Parton distributions in the LHC era: MMHT 2014 PDFs.

    Science.gov (United States)

    Harland-Lang, L A; Martin, A D; Motylinski, P; Thorne, R S

    We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the 'MSTW2008' parton sets, but they are obtained within the same basic framework. We include a variety of new data sets, from the LHC, updated Tevatron data and the HERA combined H1 and ZEUS data on the total and charm structure functions. We also improve the theoretical framework of the previous analysis. These new PDFs are compared to the 'MSTW2008' parton sets. In most cases the PDFs, and the predictions, are within one standard deviation of those of MSTW2008. The major changes are the [Formula: see text] valence quark difference at small [Formula: see text] due to an improved parameterisation and, to a lesser extent, the strange quark PDF due to the effect of certain LHC data and a better treatment of the [Formula: see text] branching ratio. We compare our MMHT PDF sets with those of other collaborations; in particular with the NNPDF3.0 sets, which are contemporary with the present analysis.

  1. Parton distributions in the LHC era: MMHT 2014 PDFs

    CERN Document Server

    Harland-Lang, L A; Motylinski, P; Thorne, R S

    2014-01-01

    We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the `MSTW2008' parton sets, but are obtained within the same basic framework. We include a variety of new data sets, from the LHC, updated Tevatron data and the HERA combined H1 and ZEUS data on the total and charm structure functions. We also improve the theoretical framework of the previous analysis. These new PDFs are compared to the `MSTW2008' parton sets. Almost always the PDFs, and the predictions, are within one standard deviation of those of MSTW2008. The major changes are the $u-d$ valence quark difference at small $x$ due to an improved parameterisation and, to a lesser extent, the strange quark PDF due to the effect of some LHC data and a better treatment of the $D \\to \\mu$ branching ratio. We compare our MMHT PDF sets with those of other collaborations; in particular with the NNPDF3.0 sets, which are contemporary...

  2. Parton distributions in the LHC era: MMHT 2014 PDFs

    Science.gov (United States)

    Harland-Lang, L. A.; Martin, A. D.; Motylinski, P.; Thorne, R. S.

    2015-05-01

    We present LO, NLO and NNLO sets of parton distribution functions (PDFs) of the proton determined from global analyses of the available hard scattering data. These MMHT2014 PDFs supersede the `MSTW2008' parton sets, but they are obtained within the same basic framework. We include a variety of new data sets, from the LHC, updated Tevatron data and the HERA combined H1 and ZEUS data on the total and charm structure functions. We also improve the theoretical framework of the previous analysis. These new PDFs are compared to the `MSTW2008' parton sets. In most cases the PDFs, and the predictions, are within one standard deviation of those of MSTW2008. The major changes are the valence quark difference at small due to an improved parameterisation and, to a lesser extent, the strange quark PDF due to the effect of certain LHC data and a better treatment of the branching ratio. We compare our MMHT PDF sets with those of other collaborations; in particular with the NNPDF3.0 sets, which are contemporary with the present analysis.

  3. Quark-gluon double parton distributions in the light-front dressed quark model

    CERN Document Server

    Kasemets, Tomas

    2016-01-01

    We study parton distributions for two partons, a quark and a gluon, in the light-front dressed quark model, with focus on correlations between the two partons. The model calculation leads to sizable spin-spin and spin-kinematic correlations of interest for studies of double parton scattering (DPS) in high-energy collisions. In particular, we find that the transverse dependence of the double parton distributions (DPDs) does not factorize within the model. The results gives insight to the strengths of correlations in different kinematical regions, which can help in constructing input DPDs in cross section calculations.

  4. Transverse momentum dependent parton distributions at small-x

    Science.gov (United States)

    Xiao, Bo-Wen; Yuan, Feng; Zhou, Jian

    2017-08-01

    We study the transverse momentum dependent (TMD) parton distributions at small-x in a consistent framework that takes into account the TMD evolution and small-x evolution simultaneously. The small-x evolution effects are included by computing the TMDs at appropriate scales in terms of the dipole scattering amplitudes, which obey the relevant Balitsky-Kovchegov equation. Meanwhile, the TMD evolution is obtained by resumming the Collins-Soper type large logarithms emerged from the calculations in small-x formalism into Sudakov factors.

  5. Transverse momentum dependent parton distributions at small-x

    Directory of Open Access Journals (Sweden)

    Bo-Wen Xiao

    2017-08-01

    Full Text Available We study the transverse momentum dependent (TMD parton distributions at small-x in a consistent framework that takes into account the TMD evolution and small-x evolution simultaneously. The small-x evolution effects are included by computing the TMDs at appropriate scales in terms of the dipole scattering amplitudes, which obey the relevant Balitsky–Kovchegov equation. Meanwhile, the TMD evolution is obtained by resumming the Collins–Soper type large logarithms emerged from the calculations in small-x formalism into Sudakov factors.

  6. A global reanalysis of nuclear parton distribution functions

    Science.gov (United States)

    Eskola, Kari J.; Kolhinen, Vesa J.; Paukkunen, Hannu; Salgado, Carlos A.

    2007-05-01

    We determine the nuclear modifications of parton distribution functions of bound protons at scales Q2 >= 1.69 GeV2 and momentum fractions 10-5 BRAHMS data for inclusive hadron production in d+Au collisions lend support for a stronger gluon shadowing at x < 0.01 and also that fairly large changes in the gluon modifications do not rapidly deteriorate the goodness of the overall fits, as long as the initial gluon modifications in the region x ~ 0.02-0.04 remain small.

  7. Nuclear parton distributions from the nCTEQ group

    CERN Document Server

    Kusina, A

    2016-01-01

    We present the nCTEQ15 global analysis of nuclear parton distribution functions (nPDFs). The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important improvement is the inclusion of pion production data from RHIC giving us a handle to constrain gluon PDF. In this presentation we briefly discuss the framework of our analysis and concentrate on the comparison of our results with those of other groups. Additionally we show a first estimate of the impact of the LHC pPb W/Z boson production data on the presented nCTEQ15 PDFs.

  8. Statistical effect in the parton distribution functions of the nucleon

    CERN Document Server

    Zhang, Yunhua; Ma, Bo-Qiang

    2008-01-01

    A new and simple statistical approach is performed to calculate the parton distribution functions (PDFs) of the nucleon in terms of light-front kinematic variables. We do not put in any extra arbitrary parameter or corrected term by hand, which guarantees the stringency of our approach. Analytic expressions of the $x$-dependent PDFs are obtained in the whole $x$ region [0,1], and some features, especially the low-$x$ rise, are more agreeable with experimental data than those in some previous instant-form statistical models in the infinite-momentum frame (IMF). Discussions on heavy-flavored PDFs are also presented.

  9. Electromagnetic contribution to charge symmetry violation in parton distributions

    Directory of Open Access Journals (Sweden)

    X.G. Wang

    2016-02-01

    Full Text Available We report a calculation of the combined effect of photon radiation and quark mass differences on charge symmetry violation (CSV in the parton distribution functions of the nucleon. Following a recent suggestion of Martin and Ryskin, the initial photon distribution is calculated in terms of coherent radiation from the proton as a whole, while the effect of the quark mass difference is based on a recent lattice QCD simulation. The distributions are then evolved to a scale at which they can be compared with experiment by including both QCD and QED radiation. Overall, at a scale of 5 GeV2, the total CSV effect on the phenomenologically important difference between the d and u-quark distributions is some 20% larger than the value based on quark mass differences alone. In total these sources of CSV account for approximately 40% of the NuTeV anomaly.

  10. Proton structure and parton distribution functions from HERA

    Directory of Open Access Journals (Sweden)

    Chekelian Vladimir

    2016-01-01

    Full Text Available The H1 and ZEUS collaborations at the electron-proton collider HERA collected e± p scattering data corresponding to an integrated luminosity of about 1 fb−1. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV, with different electric charges and longitudinal polarisation of the electron beam. Using these data inclusive neutral and charged current deep inelastic cross sections were measured over six orders of magnitude in negative four-momentum-transfer squared, Q2, and Bjorken x. A combination of all inclusive cross sections, published by the H1 and ZEUS collaborations at HERA, was performed. Using these combined HERA data and the individual H1 and ZEUS data taken using the polarised electron beams, the proton structure functions F2, FγZ2, xFγZ3 and FL were obtained, and scaling violations, electroweak unification, and polarisation effects in the charged current process were demonstrated. The combined cross sections were used as a sole input to QCD analyses at leading, next-to-leading and next-to-next-to-leading orders, providing a new set of parton distribution functions, denoted as HERAPDF2.0. An extension of the analysis by including HERA data on charm and jet production allowed a simultaneous determination of parton distributions and the strong coupling.

  11. A meta-analysis of parton distribution functions

    Science.gov (United States)

    Gao, Jun; Nadolsky, Pavel

    2014-07-01

    A "meta-analysis" is a method for comparison and combination of nonperturbative parton distribution functions (PDFs) in a nucleon obtained with heterogeneous procedures and assumptions. Each input parton distribution set is converted into a "meta-parametrization" based on a common functional form. By analyzing parameters of the meta-parametrizations from all input PDF ensembles, a combined PDF ensemble can be produced that has a smaller total number of PDF member sets than the original ensembles. The meta-parametrizations simplify the computation of the PDF uncertainty in theoretical predictions and provide an alternative to the 2010 PDF4LHC convention for combination of PDF uncertainties. As a practical example, we construct a META ensemble for computation of QCD observables at the Large Hadron Collider using the next-to-next-to-leading order PDF sets from CTEQ, MSTW, and NNPDF groups as the input. The META ensemble includes a central set that reproduces the average of LHC predictions based on the three input PDF ensembles and Hessian eigenvector sets for computing the combined PDF+α s uncertainty at a common QCD coupling strength of 0.118.

  12. A meta-analysis of parton distribution functions

    CERN Document Server

    Gao, Jun

    2014-01-01

    A "meta-analysis" is a method for comparison and combination of nonperturbative parton distribution functions (PDFs) in a nucleon obtained with heterogeneous procedures and assumptions. Each input parton distribution set is converted into a "meta-parametrization" based on a common functional form. By analyzing parameters of the meta-parametrizations from all input PDF ensembles, a combined PDF ensemble can be produced that has a smaller total number of PDF member sets than the original ensembles. The meta-parametrizations simplify the computation of the PDF uncertainty in theoretical predictions and provide an alternative to the 2010 PDF4LHC convention for combination of PDF uncertainties. As a practical example, we construct a META ensemble for computation of QCD observables at the Large Hadron Collider using the next-to-next-to-leading order PDF sets from CTEQ, MSTW, and NNPDF groups as the input. The META ensemble includes a central set that reproduces the average of LHC predictions based on the three inpu...

  13. Transverse momentum-dependent parton distribution functions in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Michael G. [New Mexico State University; Musch, Bernhard U. [Tech. University Munich; Haegler, Philipp G. [Tech. University Munich; Negele, John W. [MIT; Schaefer, Andreas [Regensburg

    2013-08-01

    A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.

  14. Evolution of twist-three parton distributions in QCD beyond the large $N_{c}$ limit

    CERN Document Server

    Braun, V M; Manashov, A N

    2000-01-01

    We formulate a consistent 1/N_c^2 expansion of the QCD evolution equations for the twist-three quark distributions g_2(x,Q^2), h_L(x,Q^2) and e(x,Q^2) based on the interpretation of the evolution as a three-particle quantum-mechanical problem with hermitian Hamiltonian. Each distribution amplitude can be decomposed in contributions of partonic components with DGLAP-type scale dependence. We calculate the 1/N_c^2 corrections to the evolution of the dominant component with the lowest anomalous dimension - the only one that survives in the large-N_c limit - and observe a good agreement with the exact numerical results for N_c=3. The 1/N_c^2 admixture of operators with higher anomalous dimensions is shown to be concentrated at a few lowest partonic components and in general is rather weak.

  15. Parton Distributions at a 100 TeV Hadron Collider

    CERN Document Server

    Rojo, Juan

    2016-01-01

    The determination of the parton distribution functions (PDFs) of the proton will be an essential input for the physics program of a future 100 TeV hadron collider. The unprecedented center-of-mass energy will require knowledge of PDFs in currently unexplored kinematical regions such as the ultra low-x region or the region of multi-TeV momentum transfers. In this contribution we briefly summarise the studies presented in the PDF section of the upcoming report on "Physics at a 100 TeV pp collider: Standard Model processes". First we map the PDF kinematical coverage in the $(x,Q^2)$ plane, quantify PDF uncertainties, and compute ratios of PDF luminosities between 100 TeV and 14 TeV. Then we show how the extreme kinematics of such collider lead to a number of remarkable PDF-related phenomena such as the top quark as a massless parton, an increased role of photon-initiated processes and the possible need of PDFs with high-energy resummation.

  16. Parton distribution of nucleon and nuclear EMC effect in a statistical model

    CERN Document Server

    Yu, Xian-Qiao

    2016-01-01

    We study the parton distribution of nucleon and nuclear EMC effect in a statistical model. We find when we choose the parameters appropriately, the predictions given by pure statistical laws can fit the experimental data well in most range of $x$, this reveal statistical law play an important role in the parton distribution of nucleon.

  17. ManeParse : A Mathematica reader for Parton Distribution Functions

    Science.gov (United States)

    Clark, D. B.; Godat, E.; Olness, F. I.

    2017-07-01

    Parton Distribution Functions (PDFs) are essential non-perturbative inputs for calculation of any observable with hadronic initial states. These PDFs are released by individual groups as discrete grids as a function of the Bjorken- x and energy scale Q. The LHAPDF project maintains a repository of PDFs from various groups in a new standardized LHAPDF6 format, additionally older formats such as the CTEQ PDS grid format are still in use. ManeParse is a package that provides access to PDFs within Mathematica to facilitate calculation and plotting. The program is self-contained so there are no external links to any FORTRAN, C or C++ programs. The package includes the option to use the built-in Mathematica interpolation or a custom cubic Lagrange interpolation routine which allows for flexibility in the extrapolation (particularly at small x-values). ManeParse is fast enough to enable simple calculations (involving even one or two integrations) in the Mathematica framework.

  18. From Bethe-Salpeter Wave functions to Generalised Parton Distributions

    Science.gov (United States)

    Mezrag, C.; Moutarde, H.; Rodríguez-Quintero, J.

    2016-09-01

    We review recent works on the modelling of generalised parton distributions within the Dyson-Schwinger formalism. We highlight how covariant computations, using the impulse approximation, allows one to fulfil most of the theoretical constraints of the GPDs. Specific attention is brought to chiral properties and especially the so-called soft pion theorem, and its link with the Axial-Vector Ward-Takahashi identity. The limitation of the impulse approximation are also explained. Beyond impulse approximation computations are reviewed in the forward case. Finally, we stress the advantages of the overlap of lightcone wave functions, and possible ways to construct covariant GPD models within this framework, in a two-body approximation.

  19. From Bethe-Salpeter Wave Functions to Generalised Parton Distributions

    CERN Document Server

    Mezrag, C; Rodriguez-Quintero, J

    2016-01-01

    We review recent works on the modelling of Generalised Parton Distributions within the Dyson-Schwinger formalism. We highlight how covariant computations, using the impulse approximation, allows one to fulfil most of the theoretical constraints of the GPDs. Specific attention is brought to chiral properties and especially the so-called soft pion theorem, and its link with the Axial-Vector Ward-Takahashi identity. The limitation of the impulse approximation are also explained. Beyond impulse approximation computations are reviewed in the forward case. Finally, we stress the advantages of the overlap of lightcone wave functions, and possible ways to construct covariant GPD models within this framework, in a two-body approximation.

  20. Transverse-momentum dependent parton distribution functions beyond leading twist in quark models

    CERN Document Server

    Lorcé, C; Schweitzer, P

    2014-01-01

    Higher-twist transverse momentum dependent parton distribution functions (TMDs) are a valuable probe of the quark-gluon dynamics in the nucleon, and play a vital role for the explanation of sizable azimuthal asymmetries in hadron production from unpolarized and polarized deep-inelastic lepton-nucleon scattering observed in experiments at CERN, DESY and Jefferson Lab. The associated observables are challenging to interpret, and still await a complete theoretical explanation, which makes guidance from models valuable. In this work we establish the formalism to describe unpolarized higher-twist TMDs in the light-front framework based on a Fock-space expansion of the nucleon state in terms of free on-shell parton states. We derive general expressions and present numerical results in a practical realization of this picture provided by the light-front constituent quark model. We review several other popular quark model approaches including free quark ensemble, bag, spectator and chiral quark-soliton model.

  1. Soft multiple parton interactions as seen in multiplicity distributions at Tevatron and LHC

    CERN Document Server

    Dremin, I M

    2011-01-01

    We analyse the multiplicity distributions of charged particles at Tevatron (p\\bar p) and LHC (pp) energies in the framework of the independent pair parton interactions (IPPI) model. It is shown that the number of soft pair parton interactions (and therefore the density of the partonic medium) is large and increases with energy. The mean multiplicity at each parton interaction grows also with energy. This growth depends on the width of the rapidity window. The similar conclusions are obtained in the multiladder exchange model (QGSM).

  2. The impact of intrinsic charm on the parton distribution functions

    Science.gov (United States)

    Aleedaneshvar, Alireza; Goharipour, Muhammad; Rostami, Saeedeh

    2016-12-01

    In this work, we present a new investigation about the impact of intrinsic charm (IC) on the physical observables, in particular, on the heavy structure function F2c. Since the IC distribution is dominant at large Bjorken variable x, normally, it is expected that it can be explored only at large x. But, by studying the correlation of the charm density in the proton with F2c, we are going to show that the IC component can also be effective at low x. To investigate further, we perform three QCD global analyses of parton distribution functions (PDFs), by including the EMC F2c data that are recognized as a clear evidence for the existence of the intrinsic charm in the proton, and also by considering the IC component. Although the fit of the EMC data is extremely poor due to the data points with lower x-values, i.e. x EMC data and IC contribution on the behaviour of PDFs.

  3. Impact of QED radiative corrections on Parton Distribution Functions

    CERN Document Server

    Sadykov, Renat

    2014-01-01

    The level of precision achieved by the experimental measurements at the LHC requires the inclusion of higher order electroweak effects to the processes of $ pp $ scattering. In particular the photon-induced process $ \\gamma\\gamma \\to \\ell^+\\ell^- $ make a significant contribution ($ \\sim 10 \\%$) to the dilepton invariant mass distribution. To evaluate the cross-section of this process one need to know the parton distribution function (PDF) of the photon in the proton $ \\gamma (x,\\mu^2) $. The aim of the current study is to investigate the impact of QED corrections on PDFs and describe the implementation of QED-modified evolution equations into beta release of new version of {\\tt QCDNUM} program. The {\\tt APPLGRID} interface to {\\tt SANC} Monte Carlo generator for fast evaluation of photon-induced cross-section is also outlined. The results were cross-checked with {\\tt partonevolution} program, {\\tt MRST2004QED} PDF set and {\\tt APFEL} program. The described developments are planned to include into {\\tt HERAFi...

  4. The impact of intrinsic charm on the parton distribution functions

    CERN Document Server

    Aleedaneshvar, Alireza; Rostami, Saeedeh

    2016-01-01

    In this work, we present a new investigation about the impact of intrinsic charm (IC) on the physical observables, in particular, on the heavy structure function $F_2^c$. Since IC distribution is dominant at large Bjorken variable $x$, normally, it is expected that it can be explored only at large $x$. But, by studying the correlation of the charm density in the proton with $F_2^c$, we are going to show that the IC component can also be effective at low $x$. To investigate further, we perform three QCD global analyses of parton distribution functions (PDFs), by including the EMC $F_2^c$ data that are recognized as clear evidence for existence of the intrinsic charm in the proton, and also by considering the IC component. Although the fit of the EMC data is extremely poor due to the data points with lower $x$ values, i.e. $x< $0.05, but these analyses can give us new information about the impact of EMC data and IC contribution on the behaviour of PDFs.

  5. Parton distributions based on a maximally consistent dataset

    CERN Document Server

    Rojo, Juan

    2014-01-01

    The choice of data that enters a global QCD analysis can have a substantial impact on the resulting parton distributions and their predictions for collider observables. One of the main reasons for this has to do with the possible presence of inconsistencies, either internal within an experiment or external between different experiments. In order to assess the robustness of the global fit, different definitions of a conservative PDF set, that is, a PDF set based on a maximally consistent dataset, have been introduced. However, these approaches are typically affected by theory biases in the selection of the dataset. In this contribution, after a brief overview of recent NNPDF developments, we propose a new, fully objective, definition of a conservative PDF set, based on the Bayesian reweighting approach. Using the new NNPDF3.0 framework, we produce various conservative sets, which turn out to be mutually in agreement within the respective PDF uncertainties, as well as with the global fit. We explore some of the...

  6. The ABM parton distributions tuned to LHC data

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institute for High Energy Physics, Protvino (Russian Federation); Bluemlein, J. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik

    2013-10-15

    We present a global fit of parton distributions at next-to-next-to-leading order (NNLO) in QCD. The fit is based on the world data for deep-inelastic scattering, fixed-target data for the Drell-Yan process and includes, for the first time, data from the Large Hadron Collider (LHC) for the Drell-Yan process and the hadro-production of top-quark pairs. The analysis applies the fixed-flavor number scheme for n{sub f}=3,4,5, uses the MS scheme for the strong coupling {alpha}{sub s} and the heavy-quark masses and keeps full account of the correlations among all non-perturbative parameters. At NNLO this returns the values of {alpha}{sub s}(M{sub Z})=0.1132{+-}0.0011 and m{sub t}(pole)=171.2{+-}2.4 GeV for the top-quark pole mass. The fit results are used to compute benchmark cross sections for Higgs production at the LHC to NNLO accuracy. We compare our results to those obtained by other groups and show that differences can be linked to different theoretical descriptions of the underlying physical processes.

  7. EPPS16: nuclear parton distributions with LHC data

    Energy Technology Data Exchange (ETDEWEB)

    Eskola, Kari J. [University of Jyvaskyla, Department of Physics, P.O. Box 35, University of Jyvaskyla (Finland); Helsinki Institute of Physics, P.O. Box 64, University of Helsinki (Finland); Paakkinen, Petja [University of Jyvaskyla, Department of Physics, P.O. Box 35, University of Jyvaskyla (Finland); Paukkunen, Hannu [University of Jyvaskyla, Department of Physics, P.O. Box 35, University of Jyvaskyla (Finland); Helsinki Institute of Physics, P.O. Box 64, University of Helsinki (Finland); Universidade de Santiago de Compostela, Instituto Galego de Fisica de Altas Enerxias (IGFAE), Galicia (Spain); Salgado, Carlos A. [Universidade de Santiago de Compostela, Instituto Galego de Fisica de Altas Enerxias (IGFAE), Galicia (Spain)

    2017-03-15

    We introduce a global analysis of collinearly factorized nuclear parton distribution functions (PDFs) including, for the first time, data constraints from LHC proton-lead collisions. In comparison to our previous analysis, EPS09, where data only from charged-lepton-nucleus deep inelastic scattering (DIS), Drell-Yan (DY) dilepton production in proton-nucleus collisions and inclusive pion production in deuteron-nucleus collisions were the input, we now increase the variety of data constraints to cover also neutrino-nucleus DIS and low-mass DY production in pion-nucleus collisions. The new LHC data significantly extend the kinematic reach of the data constraints. We now allow much more freedom for the flavor dependence of nuclear effects than in other currently available analyses. As a result, especially the uncertainty estimates are more objective flavor by flavor. The neutrino DIS plays a pivotal role in obtaining a mutually consistent behavior for both up and down valence quarks, and the LHC dijet data clearly constrain gluons at large momentum fraction. Mainly for insufficient statistics, the pion-nucleus DY and heavy-gauge-boson production in proton-lead collisions impose less visible constraints. The outcome - a new set of next-to-leading order nuclear PDFs called EPPS16 - is made available for applications in high-energy nuclear collisions. (orig.)

  8. ManeParse: a Mathematica reader for Parton Distribution Functions

    CERN Document Server

    Clark, D B; Olness, F I

    2016-01-01

    Parton Distribution Functions (PDFs) are essential non-perturbative inputs for calculation of any observable with hadronic initial states. These PDFs are released by individual groups as discrete grids as a function of the Bjorken-x and energy scale Q. The LHAPDF project at HepForge maintains a repository of PDFs from various groups in a new standardized LHAPDF6 format, as well as older formats such as the CTEQ PDS grid format. ManeParse is a package that provides PDFs within the Mathematica framework to facilitate calculating and plotting. The program is self-contained so there are no external links to any Fortran, C or C++ programs. The package includes the option to use the built-in Mathematica interpolation or a custom cubic Lagrange interpolation routine which allows for flexibility in the extrapolation (particularly at small x values). ManeParse is fast enough to enable simple calculations (involving even one or two integrations) to be easily computed in the Mathematica framework.

  9. New Generation of Parton Distributions with Uncertainties from Global QCD Analysis

    CERN Document Server

    Pumplin, Jon; Huston, J; Lai, H L; Nadolsky, P M; Tung, W K

    2002-01-01

    A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work significantly extends previous CTEQ and other global analyses on two fronts: (i) a full treatment of available experimental correlated systematic errors for both new and old data sets; (ii) a systematic and pragmatic treatment of uncertainties of the parton distributions and their physical predictions, using a recently developed eigenvector-basis approach to the Hessian method. The new gluon distribution is considerably harder than that of previous standard fits. A number of physics issues, particularly relating to the behavior of the gluon distribution, are addressed in more quantitative terms than before. Extensive results on the uncertainties of parton distributions at various scales, and on parton luminosity functions at the Tevatron RunII and the LHC, are presented. The latter provide the means to quickly estimate the uncertainties of a wide range of physical proc...

  10. Quasi-parton distribution functions: A study in the diquark spectator model

    Directory of Open Access Journals (Sweden)

    Leonard Gamberg

    2015-04-01

    Full Text Available A set of quasi-parton distribution functions (quasi-PDFs have been recently proposed by Ji. Defined as the matrix elements of equal-time spatial correlations, they can be computed on the lattice and should reduce to the standard PDFs when the proton momentum Pz is very large. Since taking the Pz→∞ limit is not feasible in lattice simulations, it is essential to provide guidance for which values of Pz the quasi-PDFs are good approximations of standard PDFs. Within the framework of the spectator diquark model, we evaluate both the up and down quarks' quasi-PDFs and standard PDFs for all leading-twist distributions (unpolarized distribution f1, helicity distribution g1, and transversity distribution h1. We find that, for intermediate parton momentum fractions x, quasi-PDFs are good approximations to standard PDFs (within 20–30% when Pz≳1.5–2 GeV. On the other hand, for large x∼1 much larger Pz>4 GeV is necessary to obtain a satisfactory agreement between the two sets. We further test the Soffer positivity bound, and find that it does not hold in general for quasi-PDFs.

  11. Standard Model Parton Distributions at Very High Energies arXiv

    CERN Document Server

    Bauer, Christian W.; Webber, Bryan R.

    We compute the leading-order evolution of parton distribution functions for all the Standard Model fermions and bosons up to energy scales far above the electroweak scale, where electroweak symmetry is restored. Our results include the 52 PDFs of the unpolarized proton, evolving according to the SU(3), SU(2), U(1), mixed SU(2) x U(1) and Yukawa interactions. We illustrate the numerical effects on parton distributions at large energies, and show that this can lead to important corrections to parton luminosities at a future 100 TeV collider.

  12. SMPDF Web: a web-based application for specialized minimal parton distribution functions

    CERN Document Server

    Carrazza, Stefano

    2016-01-01

    We present SMPDF Web, a web interface for the construction of parton distribution functions (PDFs) with a minimal number of error sets needed to represent the PDF uncertainty of specific processes (SMPDF).

  13. New Generation of Parton Distributions with Uncertainties from Global QCD Analysis

    CERN Document Server

    Tung, W K

    2002-01-01

    A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work includes a full treatment of available experimental correlated systematic errors for both new and old data sets and a systematic and pragmatic treatment of uncertainties of the parton distributions and their physical predictions. The new gluon distribution is considerably harder than that of previous standard fits. Extensive results on the uncertainties of parton distributions at various scales, and on parton luminosity functions at the Tevatron RunII and the LHC, are obtained. The latter provide the means to quickly estimate the uncertainties of a wide range of physical processes at these high-energy hadron colliders, such as the production cross sections of the $W,Z$ at the Tevatron and the LHC, and that of a light Higgs.

  14. New generation of parton distributions with uncertainties from global QCD analysis

    CERN Document Server

    Wu Ki Tung

    2002-01-01

    A new generation of parton distribution functions with increased precision and quantitative estimates of uncertainties is presented. This work includes a full treatment of available experimental correlated systematic errors for both new and old data sets and a systematic and pragmatic treatment of uncertainties of the parton distributions and their physical predictions. The new gluon distribution is considerably harder than that of previous standard fits. Extensive results on the uncertainties of parton distributions at various scales, and on parton luminosity functions at the Tevatron RunII and the LHC, are obtained. The latter provide the means to quickly estimate the uncertainties of a wide range of physical processes at these high-energy hadron colliders, such as the production cross sections of the W, Z at the Tevatron and the LHC, and that of a light Higgs. (2 refs).

  15. Working Group I: Parton distributions: Summary report for the HERA LHC Workshop Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Dittmar, M.; /Zurich, ETH; Forte, S.; /Milan U. /INFN, Milan; Glazov, A.; /DESY; Moch, S.; /DESY, Zeuthen; Alekhin, S.; Altarelli, G.; Andersen, Jeppe R.; Ball, R.D.; Blumlein, J.; Bottcher, H.; Carli, T.; Ciafaloni, M.; Colferai, D.; Cooper-Sarkar, A.; Corcella, G.; Del Debbio, L.; Dissertori, G.; Feltesse, J.; Guffanti, A.; Gwenlan, C.; Huston, J.; /Zurich, ETH /DESY, Zeuthen /Serpukhov, IHEP /CERN /Rome III U. /INFN, Rome3 /Cambridge U. /Edinburgh U. /Florence U. /INFN, Florence /Oxford U. /DSM, DAPNIA, Saclay

    2005-11-01

    We provide an assessment of the impact of parton distributions on the determination of LHC processes, and of the accuracy with which parton distributions (PDFs) can be extracted from data, in particular from current and forthcoming HERA experiments. We give an overview of reference LHC processes and their associated PDF uncertainties, and study in detail W and Z production at the LHC.We discuss the precision which may be obtained from the analysis of existing HERA data, tests of consistency of HERA data from different experiments, and the combination of these data. We determine further improvements on PDFs which may be obtained from future HERA data (including measurements of F{sub L}), and from combining present and future HERA data with present and future hadron collider data. We review the current status of knowledge of higher (NNLO) QCD corrections to perturbative evolution and deep-inelastic scattering, and provide reference results for their impact on parton evolution, and we briefly examine non-perturbative models for parton distributions. We discuss the state-of-the art in global parton fits, we assess the impact on them of various kinds of data and of theoretical corrections, by providing benchmarks of Alekhin and MRST parton distributions and a CTEQ analysis of parton fit stability, and we briefly presents proposals for alternative approaches to parton fitting. We summarize the status of large and small x resummation, by providing estimates of the impact of large x resummation on parton fits, and a comparison of different approaches to small x resummation, for which we also discuss numerical techniques.

  16. Multiplicity distributions in proton-(anti)proton and electron-positron collisions with parton recombination

    CERN Document Server

    Zborovský, I

    2011-01-01

    A new approach to phenomenological description of the charged particle multiplicity distributions in proton-(anti)proton and electron-positron collisions is presented. The observed features of the data are interpreted on the basis of stochastic-physical ideas of multiple production. Besides the processes of parton immigration and absorption, two and three patron incremental and decremental recombinations are considered. The complex behaviour of the multiplicity distributions at different energies is described by four parametric generalized hypergeometric distribution (GHD). Application of the proposed GHD to data measured by the CMS, ALICE, and ATLAS Collaborations suggests that soft multiparton recombination processes can manifest itself significantly in the structure of multiplicity distribution in pp interactions at very high energies.

  17. Flavour symmetry breaking in the kaon parton distribution amplitude

    Directory of Open Access Journals (Sweden)

    Chao Shi

    2014-11-01

    Full Text Available We compute the kaon's valence-quark (twist-two parton distribution amplitude (PDA by projecting its Poincaré-covariant Bethe–Salpeter wave-function onto the light-front. At a scale ζ=2 GeV, the PDA is a broad, concave and asymmetric function, whose peak is shifted 12–16% away from its position in QCD's conformal limit. These features are a clear expression of SU(3-flavour-symmetry breaking. They show that the heavier quark in the kaon carries more of the bound-state's momentum than the lighter quark and also that emergent phenomena in QCD modulate the magnitude of flavour-symmetry breaking: it is markedly smaller than one might expect based on the difference between light-quark current masses. Our results add to a body of evidence which indicates that at any energy scale accessible with existing or foreseeable facilities, a reliable guide to the interpretation of experiment requires the use of such nonperturbatively broadened PDAs in leading-order, leading-twist formulae for hard exclusive processes instead of the asymptotic PDA associated with QCD's conformal limit. We illustrate this via the ratio of kaon and pion electromagnetic form factors: using our nonperturbative PDAs in the appropriate formulae, FK/Fπ=1.23 at spacelike-Q2=17 GeV2, which compares satisfactorily with the value of 0.92(5 inferred in e+e− annihilation at s=17 GeV2.

  18. Global Parton Distributions for the LHC Run II

    CERN Document Server

    Ball, Richard D

    2016-01-01

    We review the next generation global PDF sets: NNPDF3.0, MMHT14 and CT14. We describe the global datasets, particularly the new data from LHC Run 1, recent developments in QCD theory and PDF methodology, improvements in combination and delivery, and future prospects for parton determination at Run 2.

  19. Ioffe-time distributions instead of parton momentum distributions in description of deep inelastic scattering

    CERN Document Server

    Braun, V M; Mankiewicz, L; Braun, V; Górnicki, P; Mankiewicz, L

    1995-01-01

    We argue that parton distributions in coordinate space provide a more natural object for nonperturbative methods compared to the usual momentum distributions in which the physics of different longitudinal distances is being mixed. To illustrate the advantages of the coordinate space formulation, we calculate the coordinate space distributions for valence quarks in the proton using the QCD sum rule approach. A remarkable agreement is found between the calculated and the experimentally measured u-quark distribution up to distances of order \\sim 2 fm in the proton rest frame. The standard calculation completely fails, however, for valence d quarks; the reasons for this discrepancy are discussed.

  20. Testing nuclear parton distributions with pA collisions at the LHC

    CERN Document Server

    Quiroga-Arias, Paloma; Wiedemann, Urs Achim

    2010-01-01

    Global perturbative QCD analyses, based on large data sets from electron-proton and hadron collider experiments, provide tight constraints on the parton distribution function (PDF) in the proton. The extension of these analyses to nuclear parton distributions (nPDF) has attracted much interest in recent years. nPDFs are needed as benchmarks for the characterization of hot QCD matter in nucleus-nucleus collisions, and attract further interest since they may show novel signatures of non-linear density-dependent QCD evolution. However, it is not known from first principles whether the factorization of long-range phenomena into process-independent parton distribution, which underlies global PDF extractions for the proton, extends to nuclear effects. As a consequence, assessing the reliability of nPDFs for benchmark calculations goes beyond testing the numerical accuracy of their extraction and requires phenomenological tests of the factorization assumption. Here we argue that a proton-nucleus collision program at...

  1. Testing collinear factorization and nuclear parton distributions with pA collisions at the LHC

    CERN Document Server

    Quiroga-Arias, Paloma; Wiedemann, Urs Achim

    2011-01-01

    Global perturbative QCD analyses, based on large data sets from electron-proton and hadron collider experiments, provide tight constraints on the parton distribution function (PDF) in the proton. The extension of these analyses to nuclear parton distributions (nPDF) has attracted much interest in recent years. nPDFs are needed as benchmarks for the characterization of hot QCD matter in nucleus-nucleus collisions, and attract further interest since they may show novel signatures of non- linear density-dependent QCD evolution. However, it is not known from first principles whether the factorization of long-range phenomena into process-independent parton distribution, which underlies global PDF extractions for the proton, extends to nuclear effects. As a consequence, assessing the reliability of nPDFs for benchmark calculations goes beyond testing the numerical accuracy of their extraction and requires phenomenological tests of the factorization assumption. Here we argue that a proton-nucleus collision program a...

  2. Evolution of the helicity and transversity Transverse-Momentum-Dependent parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Prokudin, Alexei [JLAB; Bacchetta, Alessandro [INFN-PAVIA

    2013-07-01

    We examine the QCD evolution of the helicity and transversity parton distribution functions when including also their dependence on transverse momentum. Using an appropriate definition of these polarized transverse momentum distributions (TMDs), we describe their dependence on the factorization scale and rapidity cutoff, which is essential for phenomenological applications.

  3. nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Kusina, A. [LPSC, Grenoble (France); Kovarik, K. [Munster Univ., ITP (Germany); Jezo, T. [INFN, Milan Bicocca (Italy); Clark, D. B. [Southern Methodist Univ., Dallas, TX (United States); Keppel, C. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lyonnet, F. [Southern Methodist Univ., Dallas, TX (United States); Morfin, J. G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Olness, F. I. [Southern Methodist Univ., Dallas, TX (United States); Owens, J. F. [Florida State Univ., Tallahassee, FL (United States); Schienbein, I. [LPSC, Grenoble (France); Yu, J. Y. [Southern Methodist Univ., Dallas, TX (United States)

    2015-09-04

    We present the first official release of the nCTEQ nuclear parton distribution functions with errors. The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important addition is the inclusion of pion production data from RHIC that give us a handle on constraining the gluon PDF. This contribution summarizes our results from arXiv:1509.00792, and concentrates on the comparison with other groups providing nuclear parton distributions.

  4. nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Kusina, A. [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3, Grenoble (France); Kovarik, Karol [Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Münster (Germany); Jezo, T. [Università di Milano-Bicocca and INFN, Sezione di Milano-Bicocca, Milano (Italy); Clark, D. B. [Southern Methodist Univ., Dallas, TX (United States); Keppel, Cynthia [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lyonnet, F. [Southern Methodist Univ., Dallas, TX (United States); Morfin, Jorge [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Olness, F. I. [Southern Methodist Univ., Dallas, TX (United States); Owens, Jeff [Florida State Univ., Tallahassee, FL (United States). Dept. of Physics; Schienbein, I. [Laboratoire de Physique Subatomique et de Cosmologie, Université Grenoble-Alpes, CNRS/IN2P3, Grenoble (France); Yu, J. Y. [Southern Methodist Univ., Dallas, TX (United States)

    2015-09-01

    We present the first official release of the nCTEQ nuclear parton distribution functions with errors. The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important addition is the inclusion of pion production data from RHIC that give us a handle on constraining the gluon PDF. This contribution summarizes our results from arXiv:1509.00792 and concentrates on the comparison with other groups providing nuclear parton distributions.

  5. Correlations in Double Parton Distributions: Perturbative and Non-Perturbative effects

    CERN Document Server

    Rinaldi, Matteo; Traini, Marco Claudio; Vento, Vicente

    2016-01-01

    The correct description of Double Parton Scattering (DPS), which represents a background in several channels for the search of new Physics at the LHC, requires the knowledge of double parton distribution functions (dPDFs). These quantities represent also a novel tool for the study of the three-dimensional nucleon structure, complementary to the possibilities offered by electromagnetic probes. In this paper we analyze dPDFs using Poincar\\'e covariant predictions obtained by using a Light-Front constituent quark model proposed in a recent paper, and QCD evolution. We study to what extent factorized expressions for dPDFs, which neglect, at least in part, two-parton correlations, can be used. We show that they fail in reproducing the calculated dPDFs, in particular in the valence region. Actually measurable processes at existing facilities occur at low longitudinal momenta of the interacting partons; to have contact with these processes we have analyzed correlations between pairs of partons of different kind, fin...

  6. Constraints on spin-dependent parton distributions at large x from global QCD analysis

    Directory of Open Access Journals (Sweden)

    P. Jimenez-Delgado

    2014-11-01

    Full Text Available We investigate the behavior of spin-dependent parton distribution functions (PDFs at large parton momentum fractions x in the context of global QCD analysis. We explore the constraints from existing deep-inelastic scattering data, and from theoretical expectations for the leading x→1 behavior based on hard gluon exchange in perturbative QCD. Systematic uncertainties from the dependence of the PDFs on the choice of parametrization are studied by considering functional forms motivated by orbital angular momentum arguments. Finally, we quantify the reduction in the PDF uncertainties that may be expected from future high-x data from Jefferson Lab at 12 GeV.

  7. Color effects for transverse momentum dependent parton distribution functions in hadronic processes

    CERN Document Server

    Buffing, M G A

    2014-01-01

    In the Drell-Yan process (DY) a quark and an antiquark, coming from two different protons, produce a colorless virtual photon. In the proton description, we include transverse momentum dependent parton distribution functions (TMD PDFs), which go beyond the ordinary collinear PDFs. As such, we become sensitive to polarization modes of the partons and protons that one cannot probe without accounting for transverse momenta of partons, in particular when one looks at azimuthal asymmetries. Matrix elements used in the description of hadronic processes, such as DY, require the inclusion of gauge links, coming from gluon contributions in the process, which are path-ordered exponentials tracing the color flow. In processes with two hadrons in the initial state the color flow between different parts of the process causes entanglement. We show that in the process of color disentangling each gauge link remains sensitive to this color flow. After disentanglement, we find that particular combinations of TMDs require a dif...

  8. Probing Transverse Momentum Dependent Parton Distributions in Charmonium and Bottomonium Production

    CERN Document Server

    Mukherjee, Asmita

    2015-01-01

    We propose the study of unpolarized transverse momentum dependent gluon parton distributions as well as the effect of linearly polarized gluons on transverse momentum and rapidity distributions of $J/\\psi$ and $\\Upsilon$ production within the framework of transverse momentum dependent factorization employing color evaporation model (CEM) in unpolarized proton-proton collision. We estimate the transverse momentum and rapidity distributions of $J/\\psi$ and $\\Upsilon$ at LHCb, RHIC and AFTER energies using TMD evolution formalism.

  9. Parton Distributions Functions of Pion, Kaon and Eta pseudoscalar mesons in the NJL model

    CERN Document Server

    Davidson, R M

    2002-01-01

    Parton distributions of pseudoscalar pi,K and eta mesons obtained within the NJL model using the Pauli-Villars regularization method are analyzed in terms of LO and NLO evolution, and the valence sea quark and gluon parton distributions for the pion are obtained at Q^2 = 4 GeV^2 and compared to existing parametrizations at that scale. Surprisingly, the NLO order effects turn out to be small compared to the LO ones. The valence distributions are in good agreement with experimental analyses, but the gluon and sea distributions come out to be softer in the high-x region and harder in the low-x region than the experimental analyses suggest.

  10. Photon Radiation Induced by Multiple Parton Rescattering in Deeply Inelastic Scattering

    Institute of Scientific and Technical Information of China (English)

    张本威; 王恩科

    2003-01-01

    Photon radiation induced by multiple parton rescattering and corresponding parton energy loss in eA deeply inelastic scattering are investigated by using the generalized factorization of higher twist parton distributions beyond the helicity amplitude approximation. It turns out that the behaviour of the nuclear size dependence of the parton energy loss is different in the photon and gluon radiation cases. The parton energy loss due to photon radiation depends linearly, instead of quadratically, on nuclear size due to gluon radiation.

  11. Resummation of large logarithms in the heavy quark effects on the parton distributions inside the virtual photon

    CERN Document Server

    Kitadono, Yoshio; Uematsu, Tsuneo; Ueda, Takahiro

    2010-01-01

    We discuss the resummation of the large logarithmic terms appearing in the heavy quark effects on parton distribution functions inside the virtual photon. We incorporate heavy quark mass effects by changing the initial condition of the leading-order DGLAP evolution equation. In a certain kinematical limit, we recover the logarithmic terms of the next-to-leading order heavy quark effects obtained in the previous work. This method enables us to resum the large logarithmic terms due to heavy quark mass effects on the parton distributions in the virtual photon. We numerically calculate parton distributions using the formulae derived in this work, and discuss the property of the resummed heavy quark effects.

  12. Transverse Momentum Dependent Parton Distribution Functions through SIDIS and Drell-Yan at COMPASS

    CERN Document Server

    AUTHOR|(CDS)2079419; Ramos, Sérgio; Quintans, Catarina

    The spin structure of the nucleon has been studied at the COMPASS experiment at CERN. The Semi-Inclusive Deep Inelastic Scattering (SIDIS) measurements are a powerful tool to access the Parton Distribution Functions (PDFs) and the Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs). The COMPASS polarised target gives the opportunity to measure the azimuthal modulations depending on the spin orientation and the extraction of the transverse spin asymmetries, which are convolutions of TMD PDFs of the nucleon and Fragmentation Functions (FF). The analysis of these data is done in several kinematic bins, which provides a vast input for the theoreticians to extract the TMDs and the FFs and their kinematic dependence. The TMD PDFs are also accessible through the measurement of the Drell-Yan process, in this case the transverse spin asymmetries are convolutions of two TMD PDFs, one corresponding to the annihilating quark from the beam hadron and the other to the annihilating quark from the target h...

  13. Impact of hadronic and nuclear corrections on global analysis of spin-dependent parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Delgado, Pedro [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Accardi, Alberto [Hampton University, Hampton, VA (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Melnitchouk, Wally [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-02-01

    We present the first results of a new global next-to-leading order analysis of spin-dependent parton distribution functions from the most recent world data on inclusive polarized deep-inelastic scattering, focusing in particular on the large-x and low-Q^2 regions. By directly fitting polarization asymmetries we eliminate biases introduced by using polarized structure function data extracted under nonuniform assumptions for the unpolarized structure functions. For analysis of the large-x data we implement nuclear smearing corrections for deuterium and 3He nuclei, and systematically include target mass and higher twist corrections to the g_1 and g_2 structure functions at low Q^2. We also explore the effects of Q^2 and W^2 cuts in the data sets, and the potential impact of future data on the behavior of the spin-dependent parton distributions at large x.

  14. Parton distribution functions at LO, NLO and NNLO with correlated uncertainties between orders

    CERN Document Server

    :,; Britzger, D; Camarda, S; Cooper-Sarkar, A M; Diaconu, C; Feltesse, J; Gizhko, A; Glazov, A; Kolesnikov, V; Lohwasser, K; Luszczak, A; Myronenko, V; Pirumov, H; Placakyte, R; Rabbertz, K; Radescu, V; Sapronov, A; Schoenig, A; Shushkevich, S; Slominski, W; Starovoitov, P; Sutton, M; Tomaszewska, J; Turkot, O; Watt, G; Wichmann, K; Lisovyi, M

    2014-01-01

    Sets of parton distribution functions (PDFs) of the proton are reported for the leading (LO), next-to-leading (NLO) and next-to-next-to leading order (NNLO) QCD calculations. The parton distribution functions are determined with the HERAFitter program using the data from the HERA experiments and preserving correlations between uncertainties for the LO, NLO and NNLO PDF sets. The sets are used to study cross-section ratios and their uncertainties when calculated at different orders in QCD. A reduction of the overall theoretical uncertainty is observed if correlations between the PDF sets are taken into account for the ratio of $WW$ di-boson to $Z$ boson production cross sections at the LHC.

  15. First results with twisted mass fermions towards the computation of parton distribution functions on the lattice

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Inst. for Advanced Study DIAS; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Hadjiyiannakou, Kyriakos [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Jansen, Karl; Steffens, Fernanda; Wiese, Christian [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2014-11-15

    We report on our exploratory study for the evaluation of the parton distribution functions from lattice QCD, based on a new method proposed in Ref.∝arXiv:1305.1539. Using the example of the nucleon, we compare two different methods to compute the matrix elements needed, and investigate the application of gauge link smearing. We also present first results from a large production ensemble and discuss the future challenges related to this method.

  16. First results with twisted mass fermions towards the computation of parton distribution functions on the lattice

    CERN Document Server

    Alexandrou, Constantia; Drach, Vincent; Garcia-Ramos, Elena; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian

    2014-01-01

    We report on our exploratory study for the evaluation of the parton distribution functions from lattice QCD, based on a new method proposed in Ref.~arXiv:1305.1539. Using the example of the nucleon, we compare two different methods to compute the matrix elements needed, and investigate the application of gauge link smearing. We also present first results from a large production ensemble and discuss the future challenges related to this method.

  17. Testing collinear factorization and nuclear parton distributions with pA collisions at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Quiroga-Arias, Paloma [Departamento de Fisica de PartIculas and IGFAE, Universidade de Santiago de Compostela 15706 Santiago de Compostela (Spain); Milhano, Jose Guilherme [CENTRA, Departamento de Fisica, Instituto Superior Tecnico (IST), Av. Rovisco Pais 1, P-1049-001 Lisboa (Portugal); Wiedemann, Urs Achim, E-mail: pquiroga@fpaxpl.usc.es [Physics Department, Theory Unit, CERN, CH-1211 Geneve 23 (Switzerland)

    2011-01-01

    Global perturbative QCD analyses, based on large data sets from electron-proton and hadron collider experiments, provide tight constraints on the parton distribution function (PDF) in the proton. The extension of these analyses to nuclear parton distributions (nPDF) has attracted much interest in recent years. nPDFs are needed as benchmarks for the characterization of hot QCD matter in nucleus-nucleus collisions, and attract further interest since they may show novel signatures of non- linear density-dependent QCD evolution. However, it is not known from first principles whether the factorization of long-range phenomena into process-independent parton distribution, which underlies global PDF extractions for the proton, extends to nuclear effects. As a consequence, assessing the reliability of nPDFs for benchmark calculations goes beyond testing the numerical accuracy of their extraction and requires phenomenological tests of the factorization assumption. Here we argue that a proton-nucleus collision program at the LHC would provide a set of measurements allowing for unprecedented tests of the factorization assumption underlying global nPDF fits.

  18. Achievements and open issues in the determination of polarized parton distribution functions

    CERN Document Server

    Nocera, Emanuele R

    2015-01-01

    I review the current status of the determination of helicity-dependent, or polarized, parton distribution functions from a comprehensive analysis of experimental data in perturbative quantum chromodynamics. I illustrate the latest achievements driven by new measurements in polarized proton-proton collisions at the Relativistic Heavy Ion Collider, namely the first evidence of a sizable polarized light sea quark asymmetry and of a positive polarized gluon distribution in the proton. I discuss which are the open issues in the determination of polarized distributions, and how these may be addressed in the future by ongoing, planned and proposed experimental programs.

  19. The twist-3 parton distribution function e(x) in large-Nc chiral theory

    CERN Document Server

    Cebulla, C; Schweitzer, P; Urbano, D

    2007-01-01

    The chirally-odd twist-3 parton distribution function e(x) of the nucleon is studied in the large-Nc limit in the framework of the chiral quark-soliton model. It is demonstrated that in spite of properties not shared by other distribution functions, namely the appearance of a delta(x)-singularity and quadratic divergences in e(x), an equally reliable calculation is possible. Among the most remarkable results obtained in this work is the fact that the coefficient of the delta(x)-singularity can be computed exactly in this model, avoiding involved numerics. Our results complete existing studies in literature.

  20. Block-Nordsieck summation and partonic distributions in impact parameter space

    Energy Technology Data Exchange (ETDEWEB)

    Corsetti, A. [Rome Univ. `La Sapienza (Italy). INFN, Dept. of Physics; Grau, A. [Universidada de Granada (Spain). Dep. de Fisica Teorica y del Cosmos; Pancheri, G. [INFN, Laboratori nazionali di Frascati, Rome (Italy); Srivastava, Y.N. [Perugia Univ. (Italy). INFN, Dept. of Physics

    1996-02-01

    A model for the parton distributions of hadrons in impact parameter space has been constructed using soft gluon summation. This model incorporates the salient features of distributions obtained from the intrinsic transverse momentum behaviour of hadrons. Under the assumption that the intrinsic behaviour is dominated by soft gluon emission stimulated by the scattering process, the b-spectrum becomes softer and softer as the scattering energy increases. In minijet models for the inclusive cross-sections, this will counter the increase from {sigma}{sub j}et.

  1. Symmetry breaking effect on determination of polarized and unpolarized parton distributions

    CERN Document Server

    Arbabifar, F; Khanpour, H; Tehrani, S Atashbar

    2012-01-01

    We perform a new extraction for unpolarized and polarized parton distribution functions considering a flavor decompositions for sea quarks and applying very recent deep inelastic scattering (DIS) and semi inclusive deep inelastic scattering (SIDIS) data in the fixed flavor number scheme (FFNS) framework. In the new symmetry breaking scenario the light quark and antiquark densities are extracted separately and new parametrization forms are determined for them. The heavy flavors contribution, including charm and bottom quarks, are also taken to be account for unpolarized distributions.

  2. Parton promenade into the nucleon

    Science.gov (United States)

    Voutier, Eric

    2010-01-01

    Generalized parton distributions (GPDs) offer a comprehensive picture of the nucleon struture and dynamics and provide a link between microscopic and macroscopic properties of the nucleon. These quantities, which can be interpreted as the transverse distribution of partons carrying a certain longitudinal momentum fraction of the nucleon, can be accessed in deep exclusive processes. This lecture reviews the main features of the nucleon structure as obtained from elastic and inelastic lepton scatterings and unified in the context of the GPDs framework. Particular emphasis is put on the experimental methods to access these distributions and the today experimental status.

  3. APFEL Web a web-based application for the graphical visualization of parton distribution functions

    CERN Document Server

    Carrazza, Stefano; Palazzo, Daniele; Rojo, Juan

    2015-01-01

    We present APFEL Web, a web-based application designed to provide a flexible user-friendly tool for the graphical visualization of parton distribution functions (PDFs). In this note we describe the technical design of the APFEL Web application, motivating the choices and the framework used for the development of this project. We document the basic usage of APFEL Web and show how it can be used to provide useful input for a variety of collider phenomenological studies. Finally we provide some examples showing the output generated by the application.

  4. Hadron production in deuteron-gold collisions and nuclear parton distributions

    Science.gov (United States)

    Adeluyi, Adeola; Fai, George

    2007-11-01

    We calculate nuclear modification factors RdAu, central-to-peripheral ratios, RCP, and pseudorapidity asymmetries YAsym in deuteron-gold collisions at s=200 GeV in the framework of leading-order (LO) perturbative quantum chromodynamics. We use the Eskola-Kolhinen-Salgado (EKS), the Frankfurt-Guzey-Strikman (FGS), and the Hirai-Kumano-Nagai (HKN) nuclear parton distribution functions and the Albino-Kramer-Kniehl (AKK) fragmentation functions in our calculations. Results are compared to experimental data from the BRAHMS and STAR collaborations.

  5. New limits on intrinsic charm in the nucleon from global analysis of parton distributions

    CERN Document Server

    Jimenez-Delgado, P; Londergan, J T; Melnitchouk, W

    2014-01-01

    We present a new global QCD analysis of parton distribution functions, allowing for possible nonperturbative or intrinsic charm (IC) contributions in the nucleon inspired by light-front models. The analysis makes use of the full range of available high energy scattering data for Q^2 > 1 GeV^2 and W^2 > 3.5 GeV^2, including SLAC proton and deuteron deep-inelastic scattering cross sections that were excluded in previously global analyses. The SLAC data in particular place more stringent constraints on the momentum carried by IC, with _IC _IC = 0.13 +- 0.04%, but have a very large chi^2 value.

  6. Role and Properties of Wilson Lines in Transverse-Momentum-Dependent Parton Distribution Functions

    CERN Document Server

    Stefanis, N G; Karanikas, A I

    2010-01-01

    We summarize the renormalization-group properties of transverse-momentum dependent (TMD) parton distribution functions (PDF)s arguing that in the light-cone gauge the overlapping ultraviolet and rapidity divergences cannot be solely controlled by (dimensional) regularization, but necessitate their renormalization. In doing so, we show that at the one-loop order this additional divergence entails an anomalous dimension which can be attributed to a cusp in the gauge contour at light-cone infinity. Then, we present a recent analysis of TMD PDFs which incorporates in the gauge links the Pauli term $\\sim F^{\\mu\

  7. Parton distributions at low x and gluon- and quark average multiplicities

    CERN Document Server

    Kotikov, Anatoly

    2015-01-01

    We shown the general approach for Q2 evolution of parton densities and fragmentation functions at low x based on the diagonalization. The diagonalization leads to the two components in the Q2 evolution, each of which contains a nonperturbative parameter. The values of the parameters can be found by fits of the experimental data for the deep-inelastic scattering structure function F2 and for average jet multiplicities. One of the components contains the all large logarithms ln(1/x) and produce the basic contribution at small x region. The second one is regular at low x but its contribution is very important to have a good agreement with experimental data

  8. Lattice QCD calculations of nucleon transverse momentum-dependent parton distributions using clover and domain wall fermions

    CERN Document Server

    Yoon, B; Engelhardt, M; Green, J; Gupta, R; Hägler, P; Musch, B; Negele, J; Pochinsky, A; Syritsyn, S

    2016-01-01

    We present a lattice QCD calculation of transverse momentum dependent parton distribution functions (TMDs) of protons using staple-shaped Wilson lines. For time-reversal odd observables, we calculate the generalized Sivers and Boer-Mulders transverse momentum shifts in SIDIS and DY cases, and for T-even observables we calculate the transversity related to the tensor charge and the generalized worm-gear shift. The calculation is done on two different n_f=2+1 ensembles: domain-wall fermion (DWF) with lattice spacing 0.084 fm and pion mass of 297 MeV, and clover fermion with lattice spacing 0.114 fm and pion mass of 317 MeV. The results from those two different discretizations are consistent with each other.

  9. QCD evolution equations for high energy partons in nuclear matter

    CERN Document Server

    Kinder-Geiger, Klaus; Geiger, Klaus; Mueller, Berndt

    1994-01-01

    We derive a generalized form of Altarelli-Parisi equations to decribe the time evolution of parton distributions in a nuclear medium. In the framework of the leading logarithmic approximation, we obtain a set of coupled integro- differential equations for the parton distribution functions and equations for the virtuality (``age'') distribution of partons. In addition to parton branching processes, we take into account fusion and scattering processes that are specific to QCD in medium. Detailed balance between gain and loss terms in the resulting evolution equations correctly accounts for both real and virtual contributions which yields a natural cancellation of infrared divergences.

  10. Double Parton Distributions Incorporating Perturbative QCD Evolution and Momentum and Quark Number Sum Rules

    CERN Document Server

    Gaunt, Jonathan R

    2009-01-01

    It is anticipated that hard double parton scatterings will occur frequently in the collisions of the LHC, producing interesting signals and significant backgrounds to certain single scattering processes. For double scattering processes in which the same hard scale t = ln(Q^2) is involved in both collisions, we require the double parton distributions (dPDFs) D_h^{j_1j_2}(x_1,x_2;t) in order to make theoretical predictions of their rates and properties. We describe the development of a new set of leading order dPDFs that represents an improvement on approaches used previously. First, we derive momentum and number sum rules that the dPDFs must satisfy. The fact that these must be obeyed at any scale is used to construct improved dPDFs at the input scale Q_0, for a particular choice of input scale (Q_0^2 = 1 GeV^2) and corresponding single PDFs (the MSTW2008LO set). We then describe a novel program which uses a direct x-space method to numerically integrate the LO DGLAP equation for the dPDFs, and which may be us...

  11. The uncertainty of parton distribution functions due to physical observables in a global analysis

    CERN Document Server

    Aleedaneshvar, Alireza; Rostami, Saeedeh

    2016-01-01

    The recent measurement of the differential $ \\gamma+c $-jet cross section, performed at the Tevatron collider in Run II by the D0 collaboration, is studied in a next-to-leading order (NLO) global QCD analysis to assess its impact on the proton parton distribution functions (PDFs). We show that these data lead to a significant change on the gluon and charm quark distributions. We demonstrate also that there is an inconsistency between the new high precision HERA I+II combined data and Tevatron measurement. Moreover, in this study we investigate the impact of older EMC measurements of charm structure function $F_{c}^{2}$ on the PDFs and compare the results with those gaining from the analysis of Tevatron data. We show that both of them have a same impact on PDFs, and thus can be recognized as same evidences for inefficiency of perturbative QCD in dealing with the charm production in some kinematic regions.

  12. Parton Distribution in Pseudoscalar Mesons with a Light-Front Constituent Quark Model

    CERN Document Server

    de Melo, J P B C; Tsushima, Kazuo

    2015-01-01

    We compute the distribution amplitudes of the pion and kaon in the light-front constituent quark model with the symmetric quark-bound state vertex function. In the calculation we explicitly include the flavor-SU(3) symmetry breaking effect in terms of the constituent quark masses of the up (down) and strange quarks. To calculate the kaon parton distribution functions~(PDFs), we use both the conditions in the light-cone wave function, i.e., when $\\bar{s}$ quark is on-shell, and when $u$ quark is on-shell, and make a comparison between them. The kaon PDFs calculated in the two different conditions clearly show asymmetric behaviour due to the flavor SU(3)-symmetry breaking implemented by the quark masses.

  13. Parton distribution functions probed in ultraperipheral collisions at the CERN Large Hadron Collider

    CERN Document Server

    Thomas, J; Brady, N; Clark, D B; Godat, E; Olness, F

    2016-01-01

    Vector meson production in ultra-peripheral pA and AA collisions at the CERN Large Hadron Collider (LHC) are very sensitive to Parton Distribution Functions (PDF) as well as to their leading-order, next-to-leading-order, and medium corrections. This process is a complimentary tool to explore the effects of different PDFs in particle production in proton-nucleus and nucleus-nucleus central collisions. Existing and forthcoming data available, e.g., from ALICE and CMS, may be used in conjunction with our theoretical predictions to constrain the PDFs. We make predictions for rapidity distributions and for cross sections of J/$\\psi$ , $\\psi(2S)$ and $\\Upsilon$ production at $\\sqrt{s_{NN}}=2.76$ TeV and $\\sqrt{s_{NN}}=5$ TeV. We use the second energy as representative for the Run 2 of PbPb collisions at the LHC.

  14. Prompt neutrino fluxes in the atmosphere with PROSA parton distribution functions

    CERN Document Server

    Garzelli, M V; Zenaiev, O; Cooper-Sarkar, A; Geiser, A; Lipka, K; Placakyte, R; Sigl, G

    2016-01-01

    Effects on atmospheric prompt neutrino fluxes of present uncertainties affecting the nucleon composition are studied by using the PROSA fit to parton distribution functions (PDFs). The PROSA fit extends the precision of the PDFs to low x, which is the kinematic region of relevance for high-energy neutrino production, by taking into account LHCb data on charm and bottom hadroproduction. In the range of neutrino energies explored by present Very Large Volume Neutrino Telescopes, it is found that PDF uncertainties are far smaller with respect to those due to renormalization and factorization scale variation and to assumptions on the cosmic ray composition, which at present dominate and limit our knowledge of prompt neutrino fluxes. A discussion is presented on how these uncertainties affect the expected number of atmospheric prompt neutrino events in the analysis of high-energy events characterized by interaction vertices fully contained within the instrumented volume of the detector, performed by the IceCube co...

  15. Nucleon form factors and moments of parton distributions in twisted mass lattice QCD

    CERN Document Server

    Alexandrou, C; Carbonell, J; Constantinou, M; Guichon, P; Harraud, P A; Jansen, K; Kallidonis, C; Korzec, T; Papinutto, M

    2012-01-01

    We present results on the electroweak form factors and on the lower moments of parton distributions of the nucleon, within lattice QCD using two dynamical flavors of degenerate twisted mass fermions. Results are obtained on lattices with three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm, allowing the investigation of cut-off effects. The volume dependence is examined by comparing results on two lattices of spatial length L=2.1 fm and L=2.8 fm. The simulations span pion masses in the range of 260-470 MeV. Our results are renormalized non-perturbatively and the values are given in the MS-scheme at a scale mu=2 GeV.

  16. How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function

    Science.gov (United States)

    Manohar, Aneesh; Nason, Paolo; Salam, Gavin P.; Zanderighi, Giulia

    2016-12-01

    It has become apparent in recent years that it is important, notably for a range of physics studies at the Large Hadron Collider, to have accurate knowledge on the distribution of photons in the proton. We show how the photon parton distribution function (PDF) can be determined in a model-independent manner, using electron-proton (e p ) scattering data, in effect viewing the e p →e +X process as an electron scattering off the photon field of the proton. To this end, we consider an imaginary, beyond the Standard Model process with a flavor changing photon-lepton vertex. We write its cross section in two ways: one in terms of proton structure functions, the other in terms of a photon distribution. Requiring their equivalence yields the photon distribution as an integral over proton structure functions. As a result of the good precision of e p data, we constrain the photon PDF at the level of 1%-2% over a wide range of momentum fractions.

  17. Generalized parton distributions and wide-angle exclusive scattering

    CERN Document Server

    Kroll, P

    2004-01-01

    The handbag mechanism for wide-angle exlusive scattering reactions is discussed and compared with other theoretical approaches. Its application to Compton scattering, meson photoproduction and two-photon annihilations into pairs of hadrons is reviewed.

  18. Extent of sensitivity of single photon production to parton distribution functions

    Indian Academy of Sciences (India)

    Somnath De

    2014-06-01

    We have studied the production of single isolated prompt photons in high-energy proton–proton collisions at the RHIC ($\\sqrt{s}$ = 200 GeV) and the LHC ($\\sqrt{s}$ = 7 TeV) energies within the framework of perturbative QCD upto next-to-leading order of strong coupling (). We have used five different parametrizations of parton distribution function (PDF) starting from the old CTEQ4M to the new CT10 distributions and compared our results with the recent single-prompt photon data from the PHENIX and the CMS Collaborations. The prompt photon cross-section is found to be described equally well by all the PDFs within the experimental errors at the RHIC and the LHC energies. The deviation in the single-prompt photon yield for different PDF sets is within ±20% when compared to CTEQ4M, indicating the upper bound of uncertainty in determining the gluon density. The diphoton measurement could be a potential candidate to constrain the gluon distribution inside the proton.

  19. Leading Twist Parton Distribution Amplitudes in Heavy Flavor Pseudoscalar Mesons From Dyson-Schwinger Equations of QCD

    Directory of Open Access Journals (Sweden)

    Ding Minghui

    2016-01-01

    Full Text Available We compute the valence-quark leading twist parton distribution amplitudes (PDAs of heavy pseudoscalar mesons ηc and ηb and find that they are both broader than the δ-like function while narrower than the asymptotic one. The evolution of distribution amplitude with momentum scale is then considered and PDAs will turn to a asymptotic form when the momentum goes to infinity.

  20. Parton Distributions in Nucleon on the Basis of a Relativistic Independent Quark Model

    CERN Document Server

    Barik, N

    2001-01-01

    At a low resolution scale with $Q^2={\\mu}^2$ corresponding to the nucleon bound state; deep inelastic unpolarized structure functions $F_1(x,{\\mu}^2)$ and $F_2(x,{\\mu}^2)$ are derived with correct support using the symmetric part of the hadronic tensor under some simplifying assumptions in the Bjorken limit. For doing this; the nucleon in its ground state has been represented by a suitably constructed momentum wave packet of its valence quarks in their appropriate SU(6) spin flavor configuration with the momentum probability amplitude taken phenomenologically in reference to the independent quark model of scalar-vector harmonic potential. The valence quark distribution functions $u_v(x,{\\mu}^2)$ and $d_v(x,{\\mu}^2)$, extracted from the structure function $F_1(x,{\\mu}^2)$ in a parton model interpretation, satisfy normalization constraints as well as the momentum sum-rule requirements at a bound state scale of ${\\mu}^2=0.1 GeV^2$. QCD evolution of these distribution functions taken as the inputs; yields at $Q_0...

  1. Parton distributions from high-precision collider data arXiv

    CERN Document Server

    Ball, Richard D.; Carrazza, Stefano; Del Debbio, Luigi; Forte, Stefano; Groth-Merrild, Patrick; Guffanti, Alberto; Hartland, Nathan P.; Kassabov, Zahari; Latorre, José I.; Nocera, Emanuele R.; Rojo, Juan; Rottoli, Luca; Slade, Emma; Ubiali, Maria

    We present a new set of parton distributions, NNPDF3.1, which updates NNPDF3.0, the first global set of PDFs determined using a methodology validated by a closure test. The update is motivated by recent progress in methodology and available data, and involves both. On the methodological side, we now parametrize and determine the charm PDF alongside the light quarks and gluon ones, thereby increasing from seven to eight the number of independent PDFs. On the data side, we now include the D0 electron and muon W asymmetries from the final Tevatron dataset, the complete LHCb measurements of W and Z production in the forward region at 7 and 8 TeV, and new ATLAS and CMS measurements of inclusive jet and electroweak boson production. We also include for the first time top-quark pair differential distributions and the transverse momentum of the Z bosons from ATLAS and CMS. We investigate the impact of parametrizing charm and provide evidence that the accuracy and stability of the PDFs are thereby improved. We study t...

  2. An improved global analysis of nuclear parton distribution functions including RHIC data

    CERN Document Server

    Eskola, K J; Salgado, C A

    2008-01-01

    We present an improved leading-order global DGLAP analysis of nuclear parton distribution functions (nPDFs), supplementing the traditionally used data from deep inelastic lepton-nucleus scattering and Drell-Yan dilepton production in proton-nucleus collisions, with inclusive high-$p_T$ hadron production data measured at RHIC in d+Au collisions. With the help of an extended definition of the $\\chi^2$ function, we now can more efficiently exploit the constraints the different data sets offer, for gluon shadowing in particular, and account for the overall data normalization uncertainties during the automated $\\chi^2$ minimization. The very good simultaneous fit to the nuclear hard process data used demonstrates the feasibility of a universal set of nPDFs, but also limitations become visible. The high-$p_T$ forward-rapidity hadron data of BRAHMS add a new crucial constraint into the analysis by offering a direct probe for the nuclear gluon distributions -- a sector in the nPDFs which has traditionally been very b...

  3. Parton distribution functions, αs, and heavy-quark masses for LHC Run II

    Science.gov (United States)

    Alekhin, S.; Blümlein, J.; Moch, S.; PlačakytÄ--, R.

    2017-07-01

    We determine a new set of parton distribution functions (ABMP16), the strong coupling constant αs and the quark masses mc, mb and mt in a global fit to next-to-next-to-leading order (NNLO) in QCD. The analysis uses the MS ¯ scheme for αs and all quark masses and is performed in the fixed-flavor number scheme for nf=3 , 4, 5. Essential new elements of the fit are the combined data from HERA for inclusive deep-inelastic scattering (DIS), data from the fixed-target experiments NOMAD and CHORUS for neutrino-induced DIS, data from Tevatron and the LHC for the Drell-Yan process and the hadro-production of single-top and top-quark pairs. The theory predictions include new improved approximations at NNLO for the production of heavy quarks in DIS and for the hadro-production of single-top quarks. The description of higher twist effects relevant beyond the leading twist collinear factorization approximation is refined. At NNLO, we obtain the value αs(nf=5 )(MZ)=0.1147 ±0.0008 .

  4. An improved global analysis of nuclear parton distribution functions including RHIC data

    Science.gov (United States)

    Eskola, Kari J.; Paukkunen, Hannu; Salgado, Carlos A.

    2008-07-01

    We present an improved leading-order global DGLAP analysis of nuclear parton distribution functions (nPDFs), supplementing the traditionally used data from deep inelastic lepton-nucleus scattering and Drell-Yan dilepton production in proton-nucleus collisions, with inclusive high-pT hadron production data measured at RHIC in d+Au collisions. With the help of an extended definition of the χ2 function, we now can more efficiently exploit the constraints the different data sets offer, for gluon shadowing in particular, and account for the overall data normalization uncertainties during the automated χ2 minimization. The very good simultaneous fit to the nuclear hard process data used demonstrates the feasibility of a universal set of nPDFs, but also limitations become visible. The high-pT forward-rapidity hadron data of BRAHMS add a new crucial constraint into the analysis by offering a direct probe for the nuclear gluon distributions—a sector in the nPDFs which has traditionally been very badly constrained. We obtain a strikingly stronger gluon shadowing than what has been estimated in previous global analyses. The obtained nPDFs are released as a parametrization called EPS08.

  5. Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x

    Energy Technology Data Exchange (ETDEWEB)

    Zenaiev, O.; Geiser, A.; Lipka, K.; Bluemlein, J.; Kuprash, O.; Placakyte, R.; Starovoitov, P. [DESY Hamburg and Zeuthen, Hamburg (Germany); Cooper-Sarkar, A. [University of Oxford, Oxford (United Kingdom); Garzelli, M.V.; Moch, S.O. [Universitaet Hamburg, Hamburg (Germany); Guzzi, M. [The University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); Nadolsky, P. [Southern Methodist University, Dallas, TX (United States); Rabbertz, K. [Karlsruher Institut fuer Technologie, Karlsruhe (Germany); Schienbein, I. [LPSC Grenoble, Grenoble (France); Collaboration: PROSA Collaboration

    2015-08-15

    The impact of recent measurements of heavy-flavour production in deep inelastic ep scattering and in pp collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions x of the proton momentum, down to x ∝ 5 x 10{sup -6}. This kinematic range is currently not covered by other experimental data in perturbative QCD fits. (orig.)

  6. Unpolarized Transverse Momentum Dependent Parton Distribution and Fragmentation Functions at next-to-next-to-leading order

    CERN Document Server

    Echevarria, Miguel G; Vladimirov, Alexey

    2016-01-01

    The transverse momentum dependent parton distribution/fragmentation functions (TMDs) are essential in the factorization of a number of processes like Drell-Yan scattering, vector boson production, semi-inclusive deep inelastic scattering, etc. We provide a comprehensive study of unpolarized TMDs at next-to-next-to-leading order, which includes an explicit calculation of these TMDs and an extraction of their matching coefficients onto their integrated analogues, for all flavor combinations. The obtained matching coefficients are important for any kind of phenomenology involving TMDs. In the present study each individual TMD is calculated without any reference to a specific process. We recover the known results for parton distribution functions and provide new results for the fragmentation functions. The results for the gluon transverse momentum dependent fragmentation functions are presented for the first time at one and two loops. We also discuss the structure of singularities of TMD operators and TMD matrix ...

  7. Transverse parton distribution functions at next-to-next-to-leading order: the quark-to-quark case.

    Science.gov (United States)

    Gehrmann, Thomas; Lübbert, Thomas; Yang, Li Lin

    2012-12-14

    We present a calculation of the perturbative quark-to-quark transverse parton distribution function at next-to-next-to-leading order based on a gauge invariant operator definition. We demonstrate for the first time that such a definition works beyond the first nontrivial order. We extract from our calculation the coefficient functions relevant for a next-to-next-to-next-to-leading logarithmic Q(T) resummation in a large class of processes at hadron colliders.

  8. Leading-twist parton distribution amplitudes of S-wave heavy-quarkonia

    Directory of Open Access Journals (Sweden)

    Minghui Ding

    2016-02-01

    Full Text Available The leading-twist parton distribution amplitudes (PDAs of ground-state S01 and S13 cc¯- and bb¯-quarkonia are calculated using a symmetry-preserving continuum treatment of the meson bound-state problem which unifies the properties of these heavy-quark systems with those of light-quark bound-states, including QCD's Goldstone modes. Analysing the evolution of S01 and S13 PDAs with current-quark mass, mˆq, increasing away from the chiral limit, it is found that in all cases there is a value of mˆq for which the PDA matches the asymptotic form appropriate to QCD's conformal limit and hence is insensitive to changes in renormalisation scale, ζ. This mass lies just above that associated with the s-quark. At current-quark masses associated with heavy-quarkonia, on the other hand, the PDAs are piecewise convex–concave–convex. They are much narrower than the asymptotic distribution on a large domain of ζ; but nonetheless deviate noticeably from φQQ¯(x=δ(x−1/2, which is the result in the static-quark limit. There are also material differences between S01 and S13 PDAs, and between the PDAs for different vector-meson polarisations, which vanish slowly with increasing ζ. An analysis of moments of the root-mean-square relative-velocity, 〈v2m〉, in S01 and S13 systems reveals that 〈v4〉-contributions may be needed in order to obtain a reliable estimate of matrix elements using such an expansion, especially for processes involving heavy pseudoscalar quarkonia.

  9. Higher order and heavy quark mass effects in the determination of parton distribution functions

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Valerio

    2013-07-01

    The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α{sub s} in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing

  10. Higher order and heavy quark mass effects in the determination of parton distribution functions

    Energy Technology Data Exchange (ETDEWEB)

    Bertone, Valerio

    2013-07-01

    The present thesis was devoted to the study of the inclusion of higher-order corrections and heavy quark mass effects in a PDF determination. This has been carried out in the NNPDF framework resulting originally in the NNPDF2.1 sets, which were at a later stage supplemented by the first LHC data leading to the most recent NNPDF2.3 sets. In Chapter 1 the concept of Parton Distribution Function (PDF) was introduced. We have shown how the analytical computation of the Deep-Inelastic-Scattering (DIS) process at order α{sub s} in QCD leads to initial-stale collinear divergences which, using the factorization theorem, can be reabsorbed into the PDFs. The energy dependence of PDFs is fully determined and the task is then reduced to the determination of the x (Bjorken variable) dependence. In Chapter 2 a detailed discussion of the factorization schemes presently available to include heavy quark mass effects into DIS structure functions has been given. It emerged that there are two possible basic approaches to the calculation of the DIS structure functions. In the first approach, the so-called Fixed-Flavour-Number Scheme (FFNS), the calculation is performed retaining the quark mass of the heavy flavours which provide a ''natural'' regulator for the infrared divergences. In the second approach, called Zero-Mass Variable-Flavour-Number Scheme (ZM-VFNS), the heavy quark masses are instead set to zero and this gives rise to the usual final-state collinear divergences that are absorbed into the PDFs. In addition, in the ZM-VFNS, the number of active flavours is assumed to increase by one unity as the energy of the process crosses the energy threshold of a given heavy quark. In order to obtain a factorization scheme that is accurate both at large and low energies, several prescriptions that interpolate between FFNS at low energy and ZM-VFNS at large energy have been proposed and implemented in as many PDF fits. In Chapter 2 they have been described showing

  11. Generalized Lindley Distribution

    Directory of Open Access Journals (Sweden)

    H. Zakerzadeh

    2009-06-01

    Full Text Available In this paper, we introduce a three–parameter generalization of the Lindley distribution. This includes as special cases the exponential and gamma distributions. The distribution exhibits decreasing, increasing and bathtub hazard rate depending on its parameters. We study various properties of the new distribution and provide numerical examples to show the flexibility of the model. We also derive a bivariate version of the proposed distribution.

  12. Investigating strangeness in the proton by studying the effects of Light Cone parton distributions in the Meson Cloud Model

    Science.gov (United States)

    Tuppan, Sam; Budnik, Garrett; Fox, Jordan

    2014-09-01

    The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. This research has been supported in part by the

  13. Double parton scattering. A tale of two partons

    Energy Technology Data Exchange (ETDEWEB)

    Kasemets, Tomas

    2013-08-15

    Double parton scattering in proton-proton collisions can give sizable contributions to final states in parts of phase space. We investigate the correlations between the partons participating in the two hard interactions of double parton scattering. With a detailed calculation of the differential cross section for the double Drell-Yan process we demonstrate how initial state correlations between the partons affect the rate and distribution of final state particles. We present our results with focus on correlations between the polarizations of the partons. In particular transversely polarized quarks lead to a dependence of the cross section on angles between final state particles of the two hard interactions, and thereby on the invariant mass of particle pairs. The size of the spin correlations, and therewith the degree to which the final state particles are correlated, depends on unknown double parton distributions. We derive positivity bounds on the double parton distributions that follow from their interpretation as probability densities, taking into account all possible spin correlations between two partons in an unpolarized proton. We show that the bounds are stable under homogeneous leading-order DGLAP evolution to higher scales. We make direct use of the positivity bounds in numerical investigations on the double DGLAP evolution for two linearly polarized gluons and for two transversely polarized quarks. We find that the linearly polarized gluons are likely to be negligible at high scales but that transversely polarized quarks can still play a significant role. We examine the dependence of the double parton distributions on the transverse distance between the two partons, and therewith between the two hard interactions. We further study the interplay between transverse and longitudinal variables of the distributions, as well as the impact of the differences in integration limits between the evolution equations for single and double parton distributions. (orig.)

  14. Charge symmetry at the partonic level

    Energy Technology Data Exchange (ETDEWEB)

    Londergan, J. T.; Peng, J. C.; Thomas, A. W.

    2010-07-01

    This review article discusses the experimental and theoretical status of partonic charge symmetry. It is shown how the partonic content of various structure functions gets redefined when the assumption of charge symmetry is relaxed. We review various theoretical and phenomenological models for charge symmetry violation in parton distribution functions. We summarize the current experimental upper limits on charge symmetry violation in parton distributions. A series of experiments are presented, which might reveal partonic charge symmetry violation, or alternatively might lower the current upper limits on parton charge symmetry violation.

  15. The 3-, 4-, and 5-flavor NNLO parton distributions functions from deep-inelastic-scattering data and at hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institute for High Energy Physics, Protvino (Russian Federation); Bluemlein, J.; Klein, S.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2009-08-15

    We determine the parton distribution functions (PDFs) in a next-to-next-to-leading order (NNLO) QCD-analysis of the inclusive neutral-current deep-inelastic-scattering (DIS) world data combined with the neutrino-nucleon DIS di-muon data and the fixed-target Drell-Yan data. The PDF-evolution is performed in the N{sub f} = 3 fixed-flavor scheme and supplementary sets of PDFs in the 4- and 5-flavor schemes are derived from the results in the 3-flavor scheme using matching conditions. The charm-quark DIS contribution is calculated in a general-mass variable-flavor-number (GMVFN) scheme interpolating between the zero mass 4-flavor scheme at asymptotically large values of momentum transfer Q{sup 2} and the 3-flavor scheme prescription of Buza-Matiounine-Smith-van Neerven (BMSN) at the value of Q{sup 2} = m{sub c}{sup 2}. The results in the GMVFN scheme are compared with those of the fixed-flavor scheme and other prescriptions used in global fits of PDFs. The strong coupling constant is measured at an accuracy of {approx} 1.5%. We obtain at NNLO {alpha}{sub s}(M{sub Z}{sup 2})=0.1135{+-}0.0014 in the fixed-flavor scheme and {alpha}{sub s}(M{sub Z}{sup 2})=0.1129{+-}0.0014 applying the BMSN-prescription. The implications for important standard candle and hard scattering processes at hadron colliders are illustrated. Predictions for cross sections of W{sup {+-}}- and Z-boson, the top-quark pair- and Higgs-boson production at the Tevatron and the LHC based on the 5-flavor PDFs of the present analysis are provided. (orig.)

  16. A Novel Algorithm for Extracting the Parton Distribution Amplitude from the Euclidean Bethe-Salpeter Wave Function

    CERN Document Server

    Gao, Fei; Liu, Yu-xin

    2016-01-01

    We propose a new numerical method to compute parton distribution amplitude(PDA) from the Euclidean Bethe-Salpeter wave function. The essential step is to extract the weight function in the Nakanishi representation of the Bethe-Salpeter wave function in Euclidean space, which is an ill-posed inversion problem, via the maximum entropy method(MEM). The Nakanishi weight function as well as the corresponding light-front PDA can be well determined. We confirm the previous works on PDA computation therein the different method has been performed.

  17. Neutron to proton mass difference, parton distribution functions and baryon resonances from dynamics on the Lie group u(3)

    DEFF Research Database (Denmark)

    Trinhammer, Ole

    PiMinus invariant mass in B decays. We give a controversial prediction of the relative neutron to proton mass difference 0.138 % as originating in period doublings of certain parametric states. The group space dynamics communicates with real space via the exterior derivative which projects out quark and gluon...... fields from the allospatial state. The allostate in turn is excited from space by the momentum operators which act as toroidal generators on the group manifold. Such generators can be used to trace out parton distribution functions and examples are shown to mimic the valence quark content of the proton....

  18. Three-dimensional parton distribution functions $g_{1T}$ and $h_{1L}^\\perp$ in the polarized proton-antiproton Drell-Yan process

    CERN Document Server

    Zhu, Jiacai

    2011-01-01

    We present predictions of the unweighted and weighted double spin asymmetries related to the transversal helicity distribution $g_{1T}$ and the longitudinal transversity distribution $h_{1L}^\\perp$, two of eight leading-twist transverse momentum dependent parton distributions (TMDs) or 3-dimensional parton distribution functions (3dPDFs), in the polarized proton-antiproton Drell-Yan process at typical kinematics on the Facility for Antiproton and Ion Research (FAIR). We conclude that FAIR is ideal to access the new 3dPDFs towards a detailed picture of the nucleon structure.

  19. Small- and large-x nucleon spin structure from a global QCD analysis of polarized parton distribution functions

    Directory of Open Access Journals (Sweden)

    E.R. Nocera

    2015-03-01

    Full Text Available I investigate the behavior of spin-dependent parton distribution functions in the regions of small and large momentum fractions x. I present a systematic comparison between predictions for relevant observables obtained with various models of nucleon spin structure and a recent global analysis of spin-dependent distributions, NNPDFpol1.1. Together with its unpolarized counterpart, NNPDF2.3, they form a mutually consistent set of parton distributions. Because they include most of the available experimental information, and are determined with a minimally biased methodology, these are especially suited for such a study. I show how NNPDFpol1.1 can discriminate between different theoretical models, even though NNPDF uncertainties remain large near the endpoints x→0 and x→1, due to the lack of experimental information. I discuss how our knowledge of nucleon spin structure may be improved at small x by future measurements at an Electron–Ion Collider, and at large x by recent measurements at Jefferson Lab, also in view of its 12 GeV upgrade.

  20. Double parton scattering for perturbative transverse momenta

    CERN Document Server

    Buffing, Maarten G A; Kasemets, Tomas

    2016-01-01

    The cross section for transverse momentum dependent double parton scattering involves transverse momentum dependent double parton distributions (DTMDs). In the region of perturbative transverse momentum the DTMDs can be matched onto collinear double parton distributions. We present the framework and results for this matching, as well as the evolution equations for DTMDs in the region of large distance between the two partons. We discuss explicit results for one-loop matching coefficients and evolution kernels.

  1. Radon Transform and Light-Cone Distributions

    Science.gov (United States)

    Teryaev, O. V.

    2016-08-01

    The relevance of Radon transform for generalized and transverse momentum dependent parton distributions is discussed. The new application for conditional (fracture) parton distributions and dihadron fragmentation functions is suggested.

  2. Global analysis of nuclear parton distribution functions and their uncertainties at next-to-next-to-leading order

    CERN Document Server

    Khanpour, Hamzeh

    2016-01-01

    We perform a next-to-next-to-leading order (NNLO) analysis of nuclear parton distribution functions (nPDFs) using neutral current charged-lepton ($\\ell ^\\pm$ + nucleus) deeply inelastic scattering (DIS) data and Drell-Yan (DY) cross-section ratios $\\sigma_{DY}^{A}/\\sigma_{DY}^{A^\\prime}$ for several nuclear targets. We study in details the parameterizations and the atomic mass (A) dependence of the nuclear PDFs at this order. The present nuclear PDFs global analysis provides us a complete set of nuclear PDFs, $f_i^{(A,Z)}(x,Q^2)$, with a full functional dependence on $x$, A, Q$^2$. The uncertainties of the obtained nuclear modification factors for each parton flavour are estimated using the well-known Hessian method. The nuclear charm quark distributions are also added into the analysis. We compare the parametrization results with the available data and the results of other nuclear PDFs groups. We found our nuclear PDFs to be in reasonably good agreement with them. The estimates of errors provided by our glob...

  3. NLO+NLL squark and gluino production cross-sections with threshold-improved parton distributions

    CERN Document Server

    Beenakker, Wim; Krämer, Michael; Kulesza, Anna; Laenen, Eric; Marzani, Simone; Rojo, Juan

    2015-01-01

    We present updated predictions for the cross-sections for pair production of squarks and gluinos at the LHC Run II. First of all, we update the calculations based on NLO+NLL partonic cross-sections by using the NNPDF3.0NLO global analysis. This study includes a full characterization of theoretical uncertainties from higher orders, PDFs and the strong coupling. Then, we explore the implications for this calculation of the recent NNPDF3.0 PDFs with NLO+NLL threshold resummation. We find that the shift in the results induced by the threshold-improved PDFs is within the total theory uncertainty band of the calculation based on NLO PDFs. However, we also observe that the central values of the cross-sections are modified both in a qualitative and a quantitative way, illustrating the relevance and impact of using threshold-improved PDFs together with resummed partonic cross-sections. The updated NLO+NLL cross-sections based on NNPDF3.0NLO are publicly available in the NLL-fast format, and should be an important ingr...

  4. Reply Comments on Phys. Rev. D89, 097101 (2014) "Reevaluation of the parton distribution of strange quarks in the nucleon"

    CERN Document Server

    Aschenauer, E C; Joosten, S; Rith, K; Schnell, G; Van Hulse, C

    2015-01-01

    In the "Comments on Phys. Rev. D89, 097101 (2014)", the Author presents a number of studies to conjecture that the analysis by the HERMES Collaboration presented in Phys. Rev. D89, 097101 (2014) likely suffers from effects that invalidate the leading-order analysis used in that publication. In our opinion, the Author has drawn erroneous conclusions. We present below a discussion of his arguments and the results from a repetition of that analysis using a range of parton distribution sets. The spread in those results precludes credible conclusions and demonstrates the sensitivity of the analysis to poorly known input data (unfavored FFs, strange-quark distributions, and mixed singlet and nonsinglet quantities).

  5. Summing threshold logs in a parton shower

    CERN Document Server

    Nagy, Zoltan

    2016-01-01

    When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in $\\alpha_s$ that combine to affect hard scattering cross sections and need to be summed. We show how to accomplish this in a leading approximation in the context of a parton shower Monte Carlo event generator.

  6. Summing threshold logs in a parton shower

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Zoltan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Soper, Davison E. [Oregon Univ., Eugene, OR (United States). Inst. of Theoretical Science

    2016-05-15

    When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in α{sub s} that combine to affect hard scattering cross sections and need to be summed. We show how to accomplish this in a leading approximation in the context of a parton shower Monte Carlo event generator.

  7. Open charm production in Double Parton Scattering processes in the forward kinematics

    CERN Document Server

    Blok, B

    2016-01-01

    We calculate the rate of double open charm production in the forward kinematics studied recently in the LHCb experiment. We find that the mean field approximation for the double parton GPD (Generalized parton distributions), which neglects parton - parton correlations, underestimates the rate by a factor of two. The enhancement due to the perturbative QCD correlation \\12 mechanism which explains the rates of the double parton interactions at the central rapidities is found to explain 60--80 percentof the discrepancy. We argue that the nonperturbative fluctuations leading to non-factorized(correllated)contributions to the initial conditions for the DGLAP collinear evolution of the double parton GPD play an important role in this kinematics. Combined, two correlation mechanisms provide a good description of the rate of double charm production reported by the LHCb. We also give predictions for the variation of the ratio of double and square of single inclusive rates in the discussed kinematics as a function of p...

  8. Applicability of pion-nucleus Drell-Yan data in global analysis of nuclear parton distribution functions

    CERN Document Server

    Paakkinen, Petja; Paukkunen, Hannu

    2016-01-01

    Despite the success of modern nuclear parton distribution functions (nPDFs) in describing nuclear hard-process data, they still suffer from large uncertainties. One of the poorly constrained features is the possible asymmetry in nuclear modifications of valence $u$ and $d$ quarks. We study the possibility of using pion-nucleus Drell-Yan dilepton data as a new constraint in the global analysis of nPDFs. We find that the nuclear cross-section ratios from the NA3, NA10 and E615 experiments can be used without imposing significant new theoretical uncertainties and, in particular, that these datasets may have some constraining power on the $u$/$d$ -asymmetry in nuclei.

  9. Global analysis of nuclear parton distribution functions at leading and next-to-leading order perturbative QCD

    CERN Document Server

    Paukkunen, Hannu

    2009-06-01

    This is the introductory part of my PhD thesis which consists of two parts, the separate introduction and four published articles. The introduction begins by a technically detailed description of the DGLAP evolution and the fast numerical solving method for the DGLAP equations, which has been used in the numerical works of the published articles of this thesis. A write-up of the next-to-leading order (NLO) calculations for the deeply inelastic scattering (DIS) and the Drell-Yan (DY) dilepton production cross-sections is also included. The formalism of the inclusive single hadron production at NLO is described as well, although less rigorously. The introductory part ends with a discussion of the global QCD analyses in general, with a special attention paid to the major work of this thesis, the NLO analysis of nuclear parton densities and their uncertainties.

  10. Parton Distribution Function Reweighting and Associated Uncertainties in a Search for Dark Matter with the ATLAS Detector

    Science.gov (United States)

    Lopez, Annette; ATLAS Collaboration

    2017-01-01

    Investigating the properties of a proton involved in a proton-proton collision at the Large Hadron Collider furthers our understanding of resulting processes from the collision. In the search for dark matter produced alongside a new heavy resonance, Z', or a W/Z boson, a process characterized by large missing transverse momentum from the undetected dark matter particles, parton distribution functions (PDFs) of protons were utilized to improve the Monte Carlo simulation of proton-proton collisions at &sqrt;s = 13 TeV with the ATLAS detector. The PDF set NNPDF30 leading order was used to generate events with applied cuts: missing transverse momentum greater than 250 GeV, pseudorapidity of | η | < 2 . 5 , and groomed jets with R = 1 . 0 . An algorithm was developed to do PDF reweighting from NNPDF30 leading order to the following PDF sets: NNPDF30 next-to-leading order, MMHT2014, HERAPDF20, CT14, and MSTW2008. Distributions of the transverse momentum, mass, azimuthal angle, rapidity, and pseudorapidity for the leading and subleading jets, as well as the missing transverse momentum, were produced with the PDF reweighting algorithm. The uncertainty associated with the choice of a particular PDF in creating these distributions was calculated.

  11. Comment on ''Parton distributions, d/u, and higher twist effects at high x''

    Energy Technology Data Exchange (ETDEWEB)

    W. Melnitchouki; I. R. Afnan; F. Bissey; A. W. Thomas

    1999-11-01

    In a recent Letter Yang and Bodek presented results of a new analysis of proton and deuteron structure functions in which the free neutron structure function F{sub 2}{sup n}, was extracted at large x. Knowledge of F{sub 2}{sup n} is crucial for determining the neutron/proton structure function ratio, whose x {r_arrow} 1 limit is sensitive to mechanisms of SU(6) spin-flavor symmetry breaking, and provides one of the fundamental tests of the x dependence of parton distributions in perturbative QCD. Relating nuclear structure functions to those of free nucleons is, however, not straightforward because at large x nuclear effects become quite sizeable. In particular, omitting nuclear binding or off-shell corrections can introduce errors of up to 50% in F{sub 2}{sup n}/F{sub 2}{sup p} already at x {approximately} 0.75. Rather than follow the conventional procedure of subtracting Fermi motion and binding effects in the deuteron via standard two-body wave function, Yang and Bodek instead extract F {sub 2}{sup n} by extrapolating the density dependence of the nuclear corrections to the case of the deuteron. Here the authors point out why this approach is likely to be misleading for light nuclei, and correctly applied predicts that the nuclear correction in the deuteron should be zero.

  12. Comment on Parton distributions, d/u, and higher twist effects at high x''

    Energy Technology Data Exchange (ETDEWEB)

    Melnitchouki, W.; Afnan, I.R.; Bissey, F.; Thomas, A.W.

    1999-11-01

    In a recent Letter Yang and Bodek presented results of a new analysis of proton and deuteron structure functions in which the free neutron structure function, F[sub 2][sup n], was extracted at large x. Knowledge of F[sub 2][sup n] is crucial for determining the neutron/proton structure function ratio, whose x [r arrow] 1 limit is sensitive to mechanisms of SU(6) spin-flavor symmetry breaking, and provides one of the fundamental tests of the x dependence of parton distributions in perturbative QCD. Relating nuclear structure functions to those of free nucleus is, however, not straightforward because at large x nuclear effects become quite sizeable. In particular, omitting nuclear binding or off-shell corrections can introduce errors of up to 50% in F[sub 2][sup n]/F[sub 2][sup p] already at x [approximately] 0.75. Rather than follow the conventional procedure of subtracting Fermi motion and binding effects in the deut2048 via standard two-body wave functions, Yang and Bodek instead extract F[sub 2][sup n] by extrapolating the density dependence of the nuclear corrections to the case of the deuteron. Here the authors point out why this approach is likely to be misleading for light nuclei, and correctly applied predicts that the nuclear correction in the deuteron should be zero.

  13. Unpolarized structure functions and the parton distributions for nucleon in an independent quark model

    Indian Academy of Sciences (India)

    N Barik; R N Mishra

    2001-04-01

    Considering the nucleon as consisting entirely of its valence quarks confined independently in a scalar-vector harmonic potential; unpolarized structure functions 1(,2) and 2(x,2) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions (,2) and (,2) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of 2=0.07 GeV2 to a higher $Q^{2}$ scale of $Q^{2}_{0} = 15$ GeV2 yields (, $Q^{2}_{0}$) and (, $Q^{2}_{0}$) in good agreement with experimental data. The gluon and sea-quark distributions such as (,$Q^{2}_{0}$) and (, $Q^{2}_{0}$) are dynamically generated with a reasonable qualitative agreement with the available data; using the leading order renormalization group equations with appropriate valence-quark distributions as the input.

  14. Parton Branching in Color Mutation Model

    CERN Document Server

    Hwa, R C

    1999-01-01

    The soft production problem in hadronic collisions as described in the eikonal color mutation branching model is improved in the way that the initial parton distribution is treated. Furry branching of the partons is considered as a means of describing the nonperturbative process of parton reproduction in soft interaction. The values of all the moments, and $C_q$, for q=2,...,5, as well as their energy dependences can be correctly determined by the use of only two parameters.

  15. 180th International School of Physics "Enrico Fermi" : Three-dimensional Partonic Stucture of the Nucleon

    CERN Document Server

    Avakian, H; Hasch, D; Schweitzer, P

    2012-01-01

    The three-dimensional nucleon structure is central to many theoretical and experimental activities, and research in this field has seen many advances in the last two decades, addressing fundamental questions such as the orbital motion of quarks and gluons inside the nucleons, their spatial distribution, and the correlation between spin and intrinsic motion. A real three-dimensional imaging of the nucleon as a composite object, both in momentum and coordinate space, is slowly emerging. This book presents lectures and seminars from the Enrico Fermi School: Three-Dimensional Partonic Structure of the Nucleon, held in Varenna, Italy, in June and July 2011. The topics covered include: partonic distributions, fragmentation functions and factorization in QCD; theory of transverse momentum dependent partonic distributions (TMDs) and generalized partonic distributions (GPDs); experimental methods in studies of hard scattering processes; extraction of TMDs and GPDs from data; analysis tools for azimuthal asymmetries; ...

  16. Flavour dependence of the pion and kaon form factors and parton distribution functions

    CERN Document Server

    Hutauruk, Parada T P; Thomas, Anthony W

    2016-01-01

    The separate quark flavour contributions to the pion and kaon valence quark distribution functions are studied, along with the corresponding electromagnetic form factors in the space-like region. The calculations are made using the solution of the Bethe-Salpeter equation for the model of Nambu and Jona-Lasinio with proper-time regularization. Both the pion and kaon form factors and the valence quark distribution functions reproduce many of the features of the available empirical data. The larger mass if the strange quark naturally explains the empirical fact that the ratio $u_{K^+}(x)/u_{\\pi^+}(x)$ drops below unity at large $x$, with a value of approximately $M^2_u/M_s^2$ as $x \\to 1$. With regard to the elastic form factors we report a large flavour dependence, with the $u$-quark contribution to the kaon form factor being an order of magnitude smaller than that of the $s$-quark at large $Q^2$, which may be a sensitive measure of confinement effects in QCD. Surprisingly though, the total $K^+$ and $\\pi^+$ fo...

  17. Next-to-next-to-leading order QCD analysis of spin-dependent parton distribution functions and their uncertainties: Jacobi polynomials approach

    CERN Document Server

    Shahri, F Taghavi; Tehrani, S Atashbar; Yazdi, Z Alizadeh

    2016-01-01

    We present a first global QCD analysis of next-to-next-leading-order (NNLO) contributions of the spin-dependent parton distribution functions (PPDFs) and their uncertainties using the Jacobi polynomial approach. Having the NNLO contributions of the quark-quark and gluon-quark splitting functions in perturbative QCD (Nucl. Phys. B 889 (2014) 351-400), one can obtain the evolution of longitudinally polarized parton densities of hadrons up to NNLO accuracy of QCD. A very large sets of recent and up-to-date experimental data of spin structure functions of the proton $g_1^p$, neutron $g_1^n$, and deuteron $g_1^d$ have been used in this analysis. The predictions for the NNLO calculations of the polarized parton distribution functions as well as the proton, neutron and deuteron polarized structure functions are compared with the corresponding results of the NLO approximation. We form a mutually consistent set of polarized PDFs due to the inclusion of the most available experimental data including the recently publis...

  18. Extended New Generalized Lindley Distribution

    Directory of Open Access Journals (Sweden)

    D. S. Shibu

    2016-03-01

    Full Text Available In this paper, we consider an extended version of new generalized Lindley distribution (NGLD. We refer to this new generalization as the extended new generalized Lindley distribution (ENGLD. A comprehensive account of the mathematical properties of the new distribution including estimation is presented. A real life data set is considered here to illustrate the relevance of the new model and compared it with other forms of Lindley models using method of moment estimation and method of maximum likelihood estimation.

  19. First moment of the flavour octet nucleon parton distribution function using lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Dinter, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Drach, Vincent [Univ. of Southern Denmark, Odense (Denmark). CP3-Origins and the Danish Institute for Advanced Study DIAS; Jansen, Karl [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus). Computation-based Science and Technology Research Center (CaSToRC); Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Vaquero, Alejandro [INFN, Sezione di Milano-Bicocca, Milano (Italy); Collaboration: European Twisted Mass Collaboration

    2015-03-15

    We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle {sup (8)}{sub μ{sup 2}=4} {sub GeV{sup 2}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed by S. Dinter et. al. (2012). We investigate systematic effects with a particular emphasis on the excited states contamination. We find that in the renormalization free ratio (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)}) (with left angle x right angle {sup (3)} the non-singlet moment) the excited state contributions cancel to a large extend making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, (left angle x right angle {sup (3)})/(left angle x right angle {sup (8)})=0.39(1)(4).

  20. First moment of the flavour octet nucleon parton distribution function using lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrou, Constantia [Department of Physics, University of Cyprus,P.O. Box 20537, 1678 Nicosia (Cyprus); Computation-based Science and Technology Research Center (CaSToRC),The Cyprus Institute,20 Constantinou Kavafi Street Nicosia 2121 (Cyprus); Constantinou, Martha [Department of Physics, University of Cyprus,P.O. Box 20537, 1678 Nicosia (Cyprus); Dinter, Simon [NIC, DESY,Platanenallee 6, D-15738 Zeuthen (Germany); Drach, Vincent [CP-Origins & the Danish Institute for Advanced Study DIAS,University of Southern Denmark, Campusvej 55, DK-5230 Odense M (Denmark); Hadjiyiannakou, Kyriakos [Department of Physics, University of Cyprus,P.O. Box 20537, 1678 Nicosia (Cyprus); Jansen, Karl [Department of Physics, University of Cyprus,P.O. Box 20537, 1678 Nicosia (Cyprus); Computation-based Science and Technology Research Center (CaSToRC),The Cyprus Institute,20 Constantinou Kavafi Street Nicosia 2121 (Cyprus); NIC, DESY,Platanenallee 6, D-15738 Zeuthen (Germany); Koutsou, Giannis [Department of Physics, University of Cyprus,P.O. Box 20537, 1678 Nicosia (Cyprus); Vaquero, Alejandro [INFN - Sezione di Milano-Bicocca,Edificio U2, Piazza della Scienza 3 20126 Milano (Italy); Collaboration: The ETM collaboration

    2015-06-11

    We perform a lattice computation of the flavour octet contribution to the average quark momentum in the nucleon, 〈x〉{sub μ{sup 2}=4 GeV{sup 2((8)}}. In particular, we fully take the disconnected contributions into account in our analysis for which we use a generalization of the technique developed in http://dx.doi.org/10.1007/JHEP08(2012)037. We investigate systematic effects with particular emphasis on the excited states contamination. We find that in the renormalization free ratio ((〈x〉{sup (3)})/(〈x〉{sup (8)})) (with 〈x〉{sup (3)} the non-singlet moment) the excited state contributions cancel to a large extent making this ratio a promising candidate for a comparison to phenomenological analyses. Our final result for this ratio is in agreement with the phenomenological value and we find, including systematic errors, ((〈x〉{sup (3)})/(〈x〉{sup (8)}))=0.39(1)(4).

  1. Comments on: "Measurement of Parton Distributions of Strange Quarks in the Nucleon from Charged-Kaon Production in Deep-Inelastic Scattering on the Deuteron" by the HERMES

    CERN Document Server

    Stolarski, M

    2012-01-01

    In this paper the author discusses the article by the HERMES Collaboration, Phys. Lett. B 666, 446 [arXiv:0803.2993], where several important results concerning strange quark properties in the nucleon were presented. The strange sea distribution was found to be very different from the non-strange in the Bjorken x scaling variable. In addition, the magnitude of these two distributions at low x is similar, contrary to most of the available Parton Distribution Function sets. The strange quark helicity distribution was also extracted combining inclusive and semi-inclusive kaon asymmetries. The result of the first moment of the strange quarks helicity distribution in the measured range is slightly positive, while a rather significant negative value is expected from the world polarised inclusive Deep Inelastic Scattering measurements. The author shows that a certain combination of fragmentation functions extracted from the preliminary HERMES kaon multiplicities presents a very strong Q2 dependence. Such a strong de...

  2. Study of W± and Z boson production in proton-lead collisions at the LHC with Kulagin-Petti nuclear parton distributions

    Science.gov (United States)

    Ru, Peng; Kulagin, S. A.; Petti, R.; Zhang, Ben-Wei

    2016-12-01

    We present a detailed study of the (pseudo)rapidity distributions of massive vector bosons produced in p +p and p +Pb collisions at the LHC within the next-to-leading order approximation in perturbative quantum chromodynamics. In particular, we discuss the impact of different cold nuclear matter effects on this process using the nuclear parton distributions calculated from the microscopic model developed by Kulagin and Petti (KP). This model was successfully applied to study nuclear effects in the deep-inelastic scattering and the Drell-Yan reactions off various (fixed) target nuclei. Results are compared with the recent CMS and ATLAS p +Pb data with √{s }=5.02 TeV per two colliding nucleons. We found an excellent agreement between the predictions of the KP model and the recent LHC data on W± and Z0 production in p +Pb collisions, including the differential cross sections, the forward-backward asymmetries, and W charge asymmetry. We also discuss the sensitivity of the current and future LHC data to the underlying mechanisms responsible for the nuclear modifications of parton density functions.

  3. Distributed paging for general networks

    Energy Technology Data Exchange (ETDEWEB)

    Awerbuch, B.; Bartal, Y.; Fiat, A. [Tel-Aviv Univ. (Israel)

    1996-12-31

    Distributed paging deals with the dynamic allocation of copies of files in a distributed network as to minimize the total communication cost over a sequence of read and write requests. Most previous work deals with the file allocation problem where infinite nodal memory capacity is assumed. In contrast the distributed paging problem makes the more realistic assumption that nodal memory capacity is limited. Former work on distributed paging deals with the problem only in the case of a uniform network topology. This paper gives the first distributed paging algorithm for general networks. The algorithm is competitive in storage and communication. The competitive ratios are poly-logarithmic in the total number of network nodes and the diameter of the network.

  4. Production of forward-center and forward-forward di-jets in the frameworks of $KMR$ and $MRW$ unintegrated parton distribution functions

    CERN Document Server

    Modarres, M

    2016-01-01

    The present work is devoted to study the capability in the unintegrated parton distribution functions ($UPDF$) of the $k_t$-factorization framework to describing the high-energy $QCD$ events, such as the di-jet productions from proton-proton inelastic collisions at the $LHC$ in the forward-center and the forward-forward configurations. The $UPDF$ of $Kimber$-$Martin$-$Ryskin$ ($KMR$) and $Martin$-$Ryskin$-$Watt$ ($MRW$) are generated in the leading order ($LO$) and the next-to-leading order ($NLO$), using the $Martin$-$Motylinski$-$Harland-Lang$-$Thorne$ ($MMHT2014$) $PDF$ libraries. While working in the forward-center and the forward-forward rapidity sectors, one can probe the parton densities at very low longitudinal momentum fractions ($x$). Therefore, such a computation can provide a valuable test-field for these $UPDF$. As we have stated in our previous works, it is interesting to point-out that the calculations in the $KMR$ framework illustrate a strong agreement with the experimental data, despite the ...

  5. Dynamical equilibration in strongly-interacting parton-hadron matter

    CERN Document Server

    Ozvenchuk, Vitalii; Linnyk, Olena; Gorenstein, Mark; Cassing, Wolfgang

    2011-01-01

    We study the kinetic and chemical equilibration in 'infinite' parton-hadron matter within the Parton-Hadron-String Dynamics transport approach, which is based on a dynamical quasiparticle model for partons matched to reproduce lattice-QCD results - including the partonic equation of state - in thermodynamic equilibrium. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different baryon density (or chemical potential) and energy density. The transition from initially pure partonic matter to hadronic degrees of freedom (or vice versa) occurs dynamically by interactions. Different thermodynamical distributions of the strongly-interacting quark-gluon plasma (sQGP) are addressed and discussed.

  6. Dynamical equilibration of strongly-interacting 'infinite' parton matter within the Parton-Hadron-String Dynamics (PHSD) transport approach

    CERN Document Server

    Ozvenchuk, V; Gorenstein, M I; Bratkovskaya, E L; Cassing, W

    2012-01-01

    We study the kinetic and chemical equilibration in `infinite' parton matter within the Parton-Hadron-String Dynamics off-shell transport approach, which is based on a dynamical quasiparticle model (DQPM) for partons matched to reproduce lattice QCD results -- including the partonic equation of state -- in thermodynamic equilibrium. The `infinite' parton matter is simulated by a system of quarks and gluons within a cubic box with periodic boundary conditions, at different energy densities, initialized slightly out of kinetic and chemical equilibrium. We investigate the approach of the system to equilibrium and the time scales for the equilibration of different observables. We, furthermore, study particle distributions in the strongly-interacting quark-gluon plasma (sQGP) including partonic spectral functions, momentum distributions, abundances of the different parton species and their fluctuations (scaled variance, skewness, kurtosis) in equilibrium. We also compare the results of the microscopic calculations ...

  7. The NNPDF2.2 Parton Set

    CERN Document Server

    Cerutti, Francesco

    2011-01-01

    I present a method, elaborated within the NNPDF Collaboration, that allows the inclusion of the information contained in new datasets into an existing set of parton distribution functions without the need for refitting. The method exploits bayesian inference in the space of PDF replicas: for each PDF replica a chisquare and a weight associated to it is computed. These weights are then applied to the ensemble of parton densities, producing a reweighted set of replicas. The reweighting method may be used to assess the impact of any new data or pseudodata on parton densities and thus on their predictions.

  8. An analytic initial-state parton shower

    Energy Technology Data Exchange (ETDEWEB)

    Kilian, W. [Siegen Univ. (Germany). Dept. Physik; Reuter, J.; Schmidt, S.; Wiesler, D. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-12-15

    We present a new algorithm for an analytic parton shower. While the algorithm for the final-state shower has been known in the literature, the construction of an initial-state shower along these lines is new. The aim is to have a parton shower algorithm for which the full analytic form of the probability distribution for all branchings is known. For these parton shower algorithms it is therefore possible to calculate the probability for a given event to be generated, providing the potential to reweight the event after the simulation. We develop the algorithm for this shower including scale choices and angular ordering. Merging to matrix elements is used to describe high-energy tails of distributions correctly. Finally, we compare our results with those of other parton showers and with experimental data from LEP, Tevatron and LHC. (orig.)

  9. Measurement of the triple-differential dijet cross section in proton-proton collisions at $ \\sqrt{s} = $ 8 TeV and constraints on parton distribution functions

    CERN Document Server

    Sirunyan, Albert M; CMS Collaboration; Adam, Wolfgang; Asilar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Krammer, Natascha; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krätschmer, Ilse; Liko, Dietrich; Matsushita, Takashi; Mikulec, Ivan; Rabady, Dinyar; Rad, Navid; Rahbaran, Babak; Rohringer, Herbert; Schieck, Jochen; Strauss, Josef; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Dvornikov, Oleg; Makarenko, Vladimir; Mossolov, Vladimir; Suarez Gonzalez, Juan; Zykunov, Vladimir; Shumeiko, Nikolai; Alderweireldt, Sara; De Wolf, Eddi A; Janssen, Xavier; Lauwers, Jasper; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; Daci, Nadir; De Bruyn, Isabelle; Deroover, Kevin; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; Olbrechts, Annik; Python, Quentin; Skovpen, Kirill; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Brun, Hugues; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Karapostoli, Georgia; Lenzi, Thomas; Léonard, Alexandre; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Randle-conde, Aidan; Seva, Tomislav; Vander Velde, Catherine; Vanlaer, Pascal; Vannerom, David; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Gul, Muhammad; Khvastunov, Illia; Poyraz, Deniz; Salva Diblen, Sinem; Schöfbeck, Robert; Tytgat, Michael; Van Driessche, Ward; Zaganidis, Nicolas; Bakhshiansohi, Hamed; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caudron, Adrien; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Francois, Brieuc; Giammanco, Andrea; Jafari, Abideh; Komm, Matthias; Krintiras, Georgios; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Piotrzkowski, Krzysztof; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Wertz, Sébastien; Beliy, Nikita; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Matos Figueiredo, Diego; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Torres Da Silva De Araujo, Felipe; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Dogra, Sunil; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Moon, Chang-Seong; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Shopova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Cheng, Tongguang; Jiang, Chun-Hua; Leggat, Duncan; Liu, Zhenan; Romeo, Francesco; Ruan, Manqi; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Yazgan, Efe; Zhang, Huaqiao; Zhao, Jingzhou; Ban, Yong; Chen, Geng; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Sculac, Toni; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Mesic, Benjamin; Susa, Tatjana; Ather, Mohsan Waseem; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; Abdelalim, Ahmed Ali; Mohammed, Yasser; Salama, Elsayed; Kadastik, Mario; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Pekkanen, Juska; Voutilainen, Mikko; Härkönen, Jaakko; Jarvinen, Terhi; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio

    2017-01-01

    A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 TeV using 19.7 fb$^{-1}$ of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is $\\alpha_S(M_\\text{Z}) = $ 0.1199 $\\pm$ 0.0015 (exp) $_{-0.0020}^{+0.0031}$ (theo), where $M_\\text{Z}$ is the mass of the Z boson.

  10. Measurement of Triple-Differential Dijet Cross Sections at $\\sqrt{s}=8\\,$TeV with the CMS Detector and Constraints on Parton Distribution Functions

    CERN Document Server

    CMS Collaboration

    2016-01-01

    A measurement of triple-differential dijet cross sections at a centre-of-mass energy of $\\sqrt{s} = 8\\,$TeV is presented using $19.7\\,$fb$^{-1}$ of data collected with the CMS detector in proton-proton collisions at the LHC. The cross sections are measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets. The cross sections are unfolded for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy complemented with electroweak and nonperturbative corrections. Constraints on the parton distribution functions are derived and the strong coupling constant is determined to be $\\alpha_s(M_Z) = 0.1199\\,\\pm{0.0015}\\,(\\mathrm{exp})\\, _{-0.0020}^{+0.0031}\\,(\\mathrm{theo})$.

  11. Measurement of the triple-differential dijet cross section in proton-proton collisions at sqrt(s) = 8 TeV and constraints on parton distribution functions

    Energy Technology Data Exchange (ETDEWEB)

    Sirunyan, Albert M; et al.

    2017-05-07

    A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 TeV using 19.7 inverse-femtobarns of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is alpha[S](M[Z]) = 0.1199 +/- 0.0015 (exp) -0.0020 +0.0031 (theo), where M[Z] is the mass of the Z boson.

  12. Measurement of Exclusive $π^0$ Electroproduction Structure Functions and their Relationship to Transverse Generalized Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Bedlinskiy, Ivan; Niccolai, Silvia; Stoler, Paul; Adhikari, Krishna; Aghasyan, Mher; Amaryan, Moskov; Anghinolfi, Marco; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Ball, Jacques; Baltzell, Nathan; Battaglieri, Marco; Bennett, Robert; Biselli, Angela; Bookwalter, Craig; Boyarinov, Sergey; Briscoe, William; Brooks, Williams; Burkert, Volker; Carman, Daniel; Celentano, Andrea; Chandavar, Shloka; Charles, Gabriel; Contalbrigo, Marco; Crede, Volker; D& #x27; Angelo, Annalisa; Daniel, Aji; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Deur, Alexandre; Djalali, Chaden; Doughty, David; Dupre, Raphael; Egiyan, Hovanes; El Alaoui, Ahmed; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Fegan, Stuart; Fleming, Jamie; Forest, Tony; Garcon, Michel; Gevorgyan, Nerses; Giovanetti, Kevin; Girod, Francoi-Xavier; Gohn, Wesley; Gothe, Ralf; Graham, Lewis; Griffioen, Keith; Guegan, Baptiste; Guidal, Michel; Guo, Lei; Hafidi, Kawtar; Hakobyan, Hayk; Hanretty, Charles; Heddle, David; Hicks, Kenneth; Holtrop, Maurik; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Jo, Hyon-Suk; Joo, Kyungseon; Keller, Dustin; Khanddaker, Mahbubul; Khertarpal, Puneet; Kim, Andrey; Kim, Wooyoung; Klein, Franz; Koirala, Suman; Kubarovsky, A; Kuhn, Sebastian; Kuleshov, Sergey; Kvaltine, Nicholas; Livingston, Kenneth; Lu, Haiyun; MacGregor, Ian; Mao, Yuqing; Markov, Nikolai; Martinez, D; Mayer, Michael; McKinnon, Bryan; Meyer, Curtis; Mineeva, Taisiya; Mirazita, Marco; Mokeev, Viktor; Moutarde, Herve; Munevar Espitia, Edwin; Munoz Camacho, Carlos; Nadel-Turonski, Pawel; Niculescu, Gabriel; Niculescu, Maria-Ioana; Osipenko, Mikhail; Ostrovidov, Alexander; Pappalardo, Luciano; Permuzyan, Rafayel; Park, Kijun; Park, Sungkyun; Pasyuk, Eugene; Pereira, Sergio; Phelps, Evan; Pisano, Silvia; Pogorelko, Oleg; Pozdnyakov, Sergey; Price, John; Procureur, Sebastien; Prok, Yelena; Protopopescu, Dan; Puckett, Andrew; Raue, Brian; Ricco, Giovanni; Rimal, Dipak; Ripani, Marco; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Saini, Mukesh; Salgado, Carlos; Saylor, Nicholas; Schott, Diane; Schumacher, Reinhard; Seder, Erin; Seraydaryan, Heghine; Sharabian, Youri; Smith, Gregory; Sober, Daniel; Sokhan, Daria; Stepanyan, Samuel; Strauch, Steffen; Taiuti, Mauro; Tang, Wei; Taylor, Charles; Tian, Ye; Tkachenko, Svyatoslav; Ungaro, Maurizio; Vineyard, Michael; Vlasov, Alexander; Voskanyan, Hakob; Voutier, Eric; Walford, Natalie; Watts, Daniel; Weinstein, Lawrence; Weygan, Dennis; Wood, Michael; Zachariou, Nicholas; Zhang, Jixie; Zhao, Zhiwen

    2012-09-01

    Exclusive $\\pi^0$ electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in $Q^2$, $x_B$, $t$, and $\\phi_\\pi$, in the $Q^2$ range from 1.0 to 4.6 GeV$^2$,\\ $-t$ up to 2 GeV$^2$, and $x_B$ from 0.1 to 0.58. Structure functions $\\sigma_T +\\epsilon \\sigma_L, \\sigma_{TT}$ and $\\sigma_{LT}$ were extracted as functions of $t$ for each of 17 combinations of $Q^2$ and $x_B$. The data were compared directly with two handbag-based calculations including both longitudinal and transversity GPDs. Inclusion of only longitudinal GPDs very strongly underestimates $\\sigma_T +\\epsilon \\sigma_L$ and fails to account for $\\sigma_{TT}$ and $\\sigma_{LT}$, while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity flip and helicity non-flip processes. The results confirm that exclusive $\\pi^0$ electroproduction offers direct experimental access to the transversity GPDs.

  13. Open charm production in double parton scattering processes in the forward kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Blok, B. [Technion - Israel Institute of Technology, Department of Physics, Haifa (Israel); Strikman, M. [Pennsylvania State University, Physics Department, University Park, PA (United States)

    2016-12-15

    We calculate the rate of double open charm production in the forward kinematics studied recently in the LHCb experiment. We find that the mean field approximation for the double parton GPD (generalized parton distributions), which neglects parton-parton correlations, underestimates the rate by a factor of 2. The enhancement due to the perturbative QCD correlation 1 x 2 mechanism which explains the rate of double parton interactions at the central rapidities is found to explain 60 / 80% of the discrepancy. We argue that the nonperturbative fluctuations leading to non-factorized (correlated) contributions to the initial conditions for the DGLAP collinear evolution of the double parton GPD play an important role in this kinematics. Combined, the two correlation mechanisms provide a good description of the rate of double charm production reported by the LHCb. We also give predictions for the variation of the σ{sub eff} (i.e. the ratio of double and square of single inclusive rates) in the discussed kinematics as a function of p{sub t}. The account for two correlation mechanisms strongly reduces the sensitivity of the results to the starting point of the QCD evolution. (orig.)

  14. Measurement of double-differential cross sections for top quark pair production in pp collisions at √{s} = 8 {TeV} and impact on parton distribution functions

    Science.gov (United States)

    Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; König, A.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rad, N.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Strauss, J.; Waltenberger, W.; Wulz, C.-E.; Dvornikov, O.; Makarenko, V.; Mossolov, V.; Suarez Gonzalez, J.; Zykunov, V.; Shumeiko, N.; Alderweireldt, S.; De Wolf, E. 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    2017-07-01

    Normalized double-differential cross sections for top quark pair (t\\overline{t}) production are measured in pp collisions at a centre-of-mass energy of 8 {TeV} with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7 {fb}^{-1}. The measurement is performed in the dilepton e^{± }μ ^{∓ } final state. The t\\overline{t} cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and t\\overline{t} system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured t\\overline{t} cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

  15. Measurement of double-differential cross sections for top quark pair production in pp collisions at [Formula: see text][Formula: see text] and impact on parton distribution functions.

    Science.gov (United States)

    Sirunyan, A M; Tumasyan, A; Adam, W; Asilar, E; Bergauer, T; Brandstetter, J; Brondolin, E; Dragicevic, M; Erö, J; Flechl, M; Friedl, M; Frühwirth, R; Ghete, V M; Hartl, C; Hörmann, N; Hrubec, J; Jeitler, M; König, A; Krätschmer, I; Liko, D; Matsushita, T; Mikulec, I; Rabady, D; Rad, N; Rahbaran, B; Rohringer, H; Schieck, J; Strauss, J; Waltenberger, W; Wulz, C-E; Dvornikov, O; Makarenko, V; Mossolov, V; Suarez Gonzalez, J; Zykunov, V; Shumeiko, N; Alderweireldt, S; De Wolf, E A; Janssen, X; Lauwers, J; Van De Klundert, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Van Spilbeeck, A; Abu Zeid, S; Blekman, F; D'Hondt, J; Daci, N; De Bruyn, I; Deroover, K; Lowette, S; Moortgat, S; Moreels, L; Olbrechts, A; Python, Q; Skovpen, K; Tavernier, S; Van Doninck, W; Van Mulders, P; Van Parijs, I; Brun, H; Clerbaux, B; De Lentdecker, G; Delannoy, H; Fasanella, G; Favart, L; Goldouzian, R; Grebenyuk, A; Karapostoli, G; Lenzi, T; Léonard, A; Luetic, J; Maerschalk, T; Marinov, A; Randle-Conde, A; Seva, T; Vander Velde, C; Vanlaer, P; Vannerom, D; Yonamine, R; Zenoni, F; Zhang, F; Cornelis, T; Dobur, D; Fagot, A; Gul, M; Khvastunov, I; Poyraz, D; Salva, S; Schöfbeck, R; Tytgat, M; Van Driessche, W; Yazgan, E; Zaganidis, N; Bakhshiansohi, H; Bondu, O; Brochet, S; Bruno, G; Caudron, A; De Visscher, S; Delaere, C; Delcourt, M; Francois, B; Giammanco, A; Jafari, A; Komm, M; Krintiras, G; Lemaitre, V; Magitteri, A; Mertens, A; Musich, M; Piotrzkowski, K; Quertenmont, L; Selvaggi, M; Vidal Marono, M; Wertz, S; Beliy, N; Aldá Júnior, W L; Alves, F L; Alves, G A; Brito, L; Hensel, C; Moraes, A; Pol, M E; Rebello Teles, P; Chagas, E Belchior Batista Das; Carvalho, W; Chinellato, J; Custódio, A; Da Costa, E M; Da Silveira, G G; De Jesus Damiao, D; De Oliveira Martins, C; De Souza, S Fonseca; Guativa, L M Huertas; Malbouisson, H; Matos Figueiredo, D; Mora Herrera, C; Mundim, L; Nogima, H; Prado Da Silva, W L; Santoro, A; Sznajder, A; Tonelli Manganote, E J; Torres Da Silva De Araujo, F; Vilela Pereira, A; Ahuja, S; Bernardes, C A; Dogra, S; Fernandez Perez Tomei, T R; Gregores, E M; Mercadante, P G; Moon, C S; Novaes, S F; Padula, Sandra S; Romero Abad, D; Ruiz Vargas, J C; Aleksandrov, A; Hadjiiska, R; Iaydjiev, P; Rodozov, M; Stoykova, S; Sultanov, G; Vutova, M; Dimitrov, A; Glushkov, I; Litov, L; Pavlov, B; Petkov, P; Fang, W; Ahmad, M; Bian, J G; Chen, G M; Chen, H S; Chen, M; Chen, Y; Cheng, T; Jiang, C H; Leggat, D; Liu, Z; Romeo, F; Ruan, M; Shaheen, S M; Spiezia, A; Tao, J; Wang, C; Wang, Z; Zhang, H; Zhao, J; Ban, Y; Chen, G; Li, Q; Liu, S; Mao, Y; Qian, S J; Wang, D; Xu, Z; Avila, C; Cabrera, A; Chaparro Sierra, L F; Florez, C; Gomez, J P; González Hernández, C F; Ruiz Alvarez, J D; Sanabria, J C; Godinovic, N; Lelas, D; Puljak, I; Ribeiro Cipriano, P M; Sculac, T; Antunovic, Z; Kovac, M; Brigljevic, V; Ferencek, D; Kadija, K; Mesic, B; Susa, T; Ather, M W; Attikis, A; Mavromanolakis, G; Mousa, J; Nicolaou, C; Ptochos, F; Razis, P A; Rykaczewski, H; Finger, M; Finger, M; Carrera Jarrin, E; Ellithi Kamel, A; Mahmoud, M A; Radi, A; Kadastik, M; Perrini, L; Raidal, M; Tiko, A; Veelken, C; Eerola, P; Pekkanen, J; Voutilainen, M; Härkönen, J; Järvinen, T; Karimäki, V; Kinnunen, R; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Tuominiemi, J; Tuovinen, E; Wendland, L; Talvitie, J; Tuuva, T; Besancon, M; Couderc, F; Dejardin, M; Denegri, D; Fabbro, B; Faure, J L; Favaro, C; Ferri, F; Ganjour, S; Ghosh, S; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Kucher, I; Locci, E; Machet, M; Malcles, J; Rander, J; Rosowsky, A; Titov, M; Abdulsalam, A; Antropov, I; Baffioni, S; Beaudette, F; Busson, P; Cadamuro, L; Chapon, E; Charlot, C; Davignon, O; Granier de Cassagnac, R; Jo, M; Lisniak, S; Miné, P; Nguyen, M; Ochando, C; Ortona, G; Paganini, P; Pigard, P; Regnard, S; Salerno, R; Sirois, Y; Stahl Leiton, A G; Strebler, T; Yilmaz, Y; Zabi, A; Zghiche, A; Agram, J-L; Andrea, J; Bloch, D; Brom, J-M; Buttignol, M; Chabert, E C; Chanon, N; Collard, C; Conte, E; Coubez, X; Fontaine, J-C; Gelé, D; Goerlach, U; Bihan, A-C Le; Van Hove, P; Gadrat, S; Beauceron, S; Bernet, C; Boudoul, G; Carrillo Montoya, C A; Chierici, R; Contardo, D; Courbon, B; Depasse, P; El Mamouni, H; Fay, J; Finco, L; Gascon, S; Gouzevitch, M; Grenier, G; Ille, B; Lagarde, F; Laktineh, I B; Lethuillier, M; Mirabito, L; Pequegnot, A L; Perries, S; Popov, A; Sordini, V; Vander Donckt, M; Verdier, P; Viret, S; Khvedelidze, A; Lomidze, D; Autermann, C; Beranek, S; Feld, L; Kiesel, M K; Klein, K; Lipinski, M; Preuten, M; Schomakers, C; Schulz, J; Verlage, T; Albert, A; Brodski, M; Dietz-Laursonn, E; Duchardt, D; Endres, M; Erdmann, M; Erdweg, S; Esch, T; Fischer, R; Güth, A; Hamer, M; Hebbeker, T; Heidemann, C; Hoepfner, K; Knutzen, S; Merschmeyer, M; Meyer, A

    2017-01-01

    Normalized double-differential cross sections for top quark pair ([Formula: see text]) production are measured in pp collisions at a centre-of-mass energy of 8[Formula: see text] with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7[Formula: see text]. The measurement is performed in the dilepton [Formula: see text] final state. The [Formula: see text] cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and [Formula: see text] system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured [Formula: see text] cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

  16. Quarks and partons. [Review

    Energy Technology Data Exchange (ETDEWEB)

    Paschos, E A

    1976-01-01

    This contribution reviews the evidence accumulated over the past year in favor of quarks and partons. Then it applies the quark ideas in order to interpret the neutrino-induced production of charm and the structure of neutral currents.

  17. The $NLO$ production of the $W^{\\pm}$ and $Z^0$ vector bosons via hadron collisions in the frameworks of $KMR$ and $MRW$ unintegrated parton distribution functions

    CERN Document Server

    Modarres, M; Aminzadeh-Nik, R; Hosseinkhani, H; Olanj, N

    2016-01-01

    In a series of papers, we have investigated the compatibility of the $Kimber$-$Martin$-$Ryskin$ ($KMR$) and $Martin$-$Ryskin$-$Watt$ ($MRW$) $unintegrated$ parton distribution functions ($UPDF$) as well as the description of the experimental data on the proton structure functions. The present work is a sequel to that survey, via calculation of the transverse momentum distribution of the electro-weak gauge vector bosons in the $k_t$-factorization scheme, by the means of the $KMR$, the $LO\\;MRW$ and the $NLO\\;MRW$ $UPDF$, in the next-to leading order ($NLO$). To this end, we have calculated and aggregated the invariant amplitudes of the corresponding $involved$ diagrams in the $NLO$, and counted the individual contributions in different frameworks. The preparation process for the $UPDF$ utilizes the $PDF$ of $Martin$ et al, $MSTW2008-LO$, $MSTW2008-NLO$, $MMHT2014-LO$ and $MMHT2014-NLO$ as the inputs. Afterwards, the results have been analyzed against each other, as well as the existing experimental data. Our c...

  18. APACIC++ 2.0. A PArton Cascade In C++

    Science.gov (United States)

    Krauss, F.; Schälicke, A.; Soff, G.

    2006-06-01

    The new version of the parton shower module APACIC++ for the SHERPA event generator framework is presented. It incorporates some features, that are specific for the consistent merging with multi-particle matrix elements at tree-level. This publication also includes some example results and a short description of the upgraded class structure of APACIC++, version 2.0. Program summaryTitle of program:APACIC++, version 2.0 Catalogue identifier:ADNE_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADNE_v2_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Catalogue identifier of previous version: ADNE Authors of previous version: R. Kuhn, F. Krauss, B. Iványi, G. Soff Journal reference of previous version: Comput. Phys. Commun. 134 (2001) 223 Licensing provisions: none Operating system under which the program has been tested: Linux, Unix, Darwin Programming language: C++ No. of lines in distributed program, including test data, etc.: 78 352 No. of bytes in distributed program, including test data, etc.: 2 561 276 External routines/libraries used: The makeinstall requires the autotools package Distribution format: tar gzip file Nature of the physical problem: Modern collider-based experiments in particle physics are characterized by increasing energies that are released and, thus, by a growing number of particles that are produced. The large numbers of involved particles renders it impossible to derive fully analytical predictions for a detailed description of the final state. In addition, the transformation of the partons of perturbative quantum field theory into the experimentally observable hadrons is until now not understood on a quantitative level. These obstacles prevent a direct comparison of analytical predictions with experimental data, and simulation tools need to be employed to bridge this gap. Method of solution: The event generator SHERPA with a new version of the parton shower module APACIC++ is able to

  19. Nucleon Parton Structure from Continuum QCD

    Science.gov (United States)

    Bednar, Kyle; Cloet, Ian; Tandy, Peter

    2017-01-01

    The parton structure of the nucleon is investigated using QCD's Dyson-Schwinger equations (DSEs). This formalism builds in numerous essential features of QCD, for example, the dressing of parton propagators and dynamical formation of non-pointlike di-quark correlations. All needed elements of the approach, including the nucleon wave function solution from a Poincaré covariant Faddeev equation, are encoded in spectral-type representations in the Nakanishi style. This facilitates calculations and the necessary connections between Euclidean and Minkowski metrics. As a first step results for the nucleon quark distribution functions will be presented. The extension to the transverse momentum-dependent parton distributions (TMDs) also be discussed. Supported by NSF Grant No. PHY-1516138.

  20. Coxian Representations of Generalized Erlang Distributions

    Institute of Scientific and Technical Information of China (English)

    Qi-ming He; Han-qin Zhang

    2009-01-01

    This paper studies Coxian representations of generalized Erlang distributions. A nonlinear program is derived for computing the parameters of minimal Coxian representations of generalized Erlang distributions.The nonlinear program is also used to characterize the triangular order and the admissible region of generalized Erlang distributions. It is shown that the admissible region associated with a triangular order may not be convex. For generalized Erlang distributions of ME-order 3, a minimal Coxian representation is found explicitly.In addition, an algorithm is developed for computing a special type of ordered Coxian representations - the bivariate Coxian representation - for generalized Erlang distributions.

  1. Generalized TMDs and the exclusive double Drell-Yan process

    Science.gov (United States)

    Bhattacharya, Shohini; Metz, Andreas; Zhou, Jian

    2017-08-01

    Generalized transverse momentum dependent parton distributions (GTMDs) are the most general parton correlation functions of hadrons. By considering the exclusive double Drell-Yan process it is shown for the first time how quark GTMDs can be measured. Specific GTMDs can be addressed by means of polarization observables.

  2. The Transmuted Generalized Inverse Weibull Distribution

    Directory of Open Access Journals (Sweden)

    Faton Merovci

    2014-05-01

    Full Text Available A generalization of the generalized inverse Weibull distribution the so-called transmuted generalized inverse Weibull distribution is proposed and studied. We will use the quadratic rank transmutation map (QRTM in order to generate a flexible family of probability distributions taking the generalized inverseWeibull distribution as the base value distribution by introducing a new parameter that would offer more distributional flexibility. Various structural properties including explicit expressions for the moments, quantiles, and moment generating function of the new distribution are derived. We propose the method of maximum likelihood for estimating the model parameters and obtain the observed information matrix. A real data set are used to compare the flexibility of the transmuted version versus the generalized inverse Weibull distribution.

  3. Parton Dynamics at PHENIX

    CERN Document Server

    Osborn, J D

    2015-01-01

    Investigating partonic interactions is one of the primary goals of the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). RHIC is specially tailored for studying intrinsic partonic spin-momentum correlations due to its unique ability to collide polarized proton beams. Transverse single-spin asymmetries of order 10% have been measured in PHENIX at center of mass energies from 62.4 GeV to 200 GeV, similar to previous measurements. These results indicate that there exist partonic transverse momentum effects within the proton and/or within the process of hadronization. The MPC-EX, a new silicon-tungsten preshower detector at PHENIX, has taken data for the first time this year with the intent of shedding further light on the origins of these asymmetries. A review of the status of the detector and of future planned measurements will be presented. An overview of ongoing work by PHENIX aimed at measuring intrinsic partonic transverse momentum will be discussed.

  4. Parton model sum rules

    CERN Document Server

    Hinchliffe, Ian; Hinchliffe, Ian; Kwiatkowski, Axel

    1996-01-01

    This review article discusses the experimental and theoretical status of various Parton Model sum rules. The basis of the sum rules in perturbative QCD is discussed. Their use in extracting the value of the strong coupling constant is evaluated and the failure of the naive version of some of these rules is assessed.

  5. Comments on Phys. Rev. D89 (2014) 097101 "Reevaluation of the parton distribution of strange quarks in the nucleon"

    CERN Document Server

    Stolarski, M

    2014-01-01

    The HERMES collaboration in Phys. Rev. D89 (2014) 097101 extracted information about the strange quark density in the nucleon. One of the main results is an observation that the shape of the extracted density is very different from the shapes of the strange quark density from global QCD fits and also from that of the light antiquarks. In this paper systematic studies on the HERMES published multiplicity of pion and kaon data are presented. It is shown that the conclusions concerning the strange quark distribution in the nucleon reached in Phys. Rev. D89 (2014) 097101 are at the moment premature.

  6. The use of generalized functions and distributions in general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Steinbauer, R [Department of Mathematics, University of Vienna, Nordbergstrasse 15, A-1090 Wien (Austria); Vickers, J A [School of Mathematics, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2006-05-21

    We review the extent to which one can use classical distribution theory in describing solutions of Einstein's equations. We show that there are a number of physically interesting cases which cannot be treated using distribution theory but require a more general concept. We describe a mathematical theory of nonlinear generalized functions based on Colombeau algebras and show how this may be applied in general relativity. We end by discussing the concept of singularity in general relativity and show that certain solutions with weak singularities may be regarded as distributional solutions of Einstein's equations. (topical review)

  7. Thermalization through parton transport

    CERN Document Server

    Zhang, Bin

    2009-01-01

    A radiative transport model is used to study kinetic equilibration during the early stage of a relativistic heavy ion collision. The parton system is found to be able to overcome expansion and move toward thermalization via parton collisions. Scaling behaviors show up in both the pressure anisotropy and the energy density evolutions. In particular, the pressure anisotropy evolution shows an approximate alpha_s scaling when radiative processes are included. It approaches an asymptotic time evolution on a time scale of 1 to 2 fm/c. The energy density evolution shows an asymptotic time evolution that decreases slower than the ideal hydro evolution. These observations indicate that partial thermalization can be achieved and viscosity is important for the evolution during the early longitudinal expansion stage of a relativistic heavy ion collision.

  8. The Vincia Parton Shower

    CERN Document Server

    Giele, Walter T.; Kosower, David A.; Laenen, Eric; Larkoski, Andrew J.; Lopez-Villarejo, Juan J.; Ritzmann, Mathias; Skands, Peter

    2013-01-01

    We summarize recent developments in the VINCIA parton shower. After a brief review of the basics of the formalism, the extension of VINCIA to hadron collisions is sketched. We then turn to improvements of the efficiency of tree-level matching by making the shower history unique and by incorporating identified helicities. We conclude with an overview of matching to one-loop matrix elements.

  9. Are partons confined tachyons?

    Energy Technology Data Exchange (ETDEWEB)

    Noyes, H.P.

    1996-03-01

    The author notes that if hadrons are gravitationally stabilized ``black holes``, as discrete physics suggests, it is possible that partons, and in particular quarks, could be modeled as tachyons, i.e. particles having v{sup 2} > c{sup 2}, without conflict with the observational fact that neither quarks nor tachyons have appeared as ``free particles``. Some consequences of this model are explored.

  10. Dynamical equilibration in strongly-interacting parton-hadron matter

    Directory of Open Access Journals (Sweden)

    Gorenstein M.

    2011-04-01

    Full Text Available We study the kinetic and chemical equilibration in 'infinite' parton-hadron matter within the Parton-Hadron-String Dynamics transport approach, which is based on a dynamical quasiparticle model for partons matched to reproduce lattice-QCD results – including the partonic equation of state – in thermodynamic equilibrium. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different baryon density (or chemical potential and energy density. The transition from initially pure partonic matter to hadronic degrees of freedom (or vice versa occurs dynamically by interactions. Different thermody-namical distributions of the strongly-interacting quark-gluon plasma (sQGP are addressed and discussed.

  11. Measurement of double-differential cross sections for top quark pair production in pp collisions at $\\sqrt{s} = $ 8 TeV and impact on parton distribution functions

    CERN Document Server

    Sirunyan, Albert M; Adam, Wolfgang; Aşılar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krätschmer, Ilse; Liko, Dietrich; Matsushita, Takashi; Mikulec, Ivan; Rabady, Dinyar; Rad, Navid; Rahbaran, Babak; Rohringer, Herbert; Schieck, Jochen; Strauss, Josef; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Dvornikov, Oleg; Makarenko, Vladimir; Mossolov, Vladimir; Suarez Gonzalez, Juan; Zykunov, Vladimir; Shumeiko, Nikolai; Alderweireldt, Sara; De Wolf, Eddi A; Janssen, Xavier; Lauwers, Jasper; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; Daci, Nadir; De Bruyn, Isabelle; Deroover, Kevin; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; Olbrechts, Annik; Python, Quentin; Skovpen, Kirill; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Brun, Hugues; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Karapostoli, Georgia; Lenzi, Thomas; Léonard, Alexandre; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Randle-conde, Aidan; Seva, Tomislav; Vander Velde, Catherine; Vanlaer, Pascal; Vannerom, David; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Gul, Muhammad; Khvastunov, Illia; Poyraz, Deniz; Salva Diblen, Sinem; Schöfbeck, Robert; Tytgat, Michael; Van Driessche, Ward; Yazgan, Efe; Zaganidis, Nicolas; Bakhshiansohi, Hamed; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caudron, Adrien; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Francois, Brieuc; Giammanco, Andrea; Jafari, Abideh; Komm, Matthias; Krintiras, Georgios; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Piotrzkowski, Krzysztof; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Wertz, Sébastien; Beliy, Nikita; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Matos Figueiredo, Diego; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Torres Da Silva De Araujo, Felipe; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Dogra, Sunil; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Moon, Chang-Seong; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Vutova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Cheng, Tongguang; Jiang, Chun-Hua; Leggat, Duncan; Liu, Zhenan; Romeo, Francesco; Ruan, Manqi; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Zhang, Huaqiao; Zhao, Jingzhou; Ban, Yong; Chen, Geng; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Sculac, Toni; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Mesic, Benjamin; Susa, Tatjana; Ather, Mohsan Waseem; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; Ellithi Kamel, Ali; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Pekkanen, Juska; Voutilainen, Mikko; Härkönen, Jaakko; Jarvinen, Terhi; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Tuominiemi, Jorma; Tuovinen, Esa; Wendland, Lauri; Talvitie, Joonas; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Favaro, Carlotta; Ferri, Federico; Ganjour, Serguei; Ghosh, Saranya; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Kucher, Inna; Locci, Elizabeth; Machet, Martina; Malcles, Julie; Rander, John; Rosowsky, André; Titov, Maksym; Abdulsalam, Abdulla; Antropov, Iurii; Baffioni, Stephanie; Beaudette, Florian; Busson, Philippe; Cadamuro, Luca; Chapon, Emilien; Charlot, Claude; Davignon, Olivier; Granier de Cassagnac, Raphael; Jo, Mihee; Lisniak, Stanislav; Miné, Philippe; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Paganini, Pascal; Pigard, Philipp; Regnard, Simon; Salerno, Roberto; Sirois, Yves; Stahl Leiton, Andre Govinda; Strebler, Thomas; Yilmaz, Yetkin; Zabi, Alexandre; Zghiche, Amina; Agram, Jean-Laurent; Andrea, Jeremy; Bloch, Daniel; Brom, Jean-Marie; Buttignol, Michael; Chabert, Eric Christian; Chanon, Nicolas; Collard, Caroline; Conte, Eric; Coubez, Xavier; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Le Bihan, Anne-Catherine; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Bernet, Colin; Boudoul, Gaelle; Carrillo Montoya, Camilo Andres; Chierici, Roberto; Contardo, Didier; Courbon, Benoit; Depasse, Pierre; El Mamouni, Houmani; Fay, Jean; Finco, Linda; Gascon, Susan; Gouzevitch, Maxime; Grenier, Gérald; Ille, Bernard; Lagarde, Francois; Laktineh, Imad Baptiste; Lethuillier, Morgan; Mirabito, Laurent; Pequegnot, Anne-Laure; Perries, Stephane; Popov, Andrey; Sordini, Viola; Vander Donckt, Muriel; Verdier, Patrice; Viret, Sébastien; Khvedelidze, Arsen; Lomidze, David; Autermann, Christian; Beranek, Sarah; Feld, Lutz; Kiesel, Maximilian Knut; Klein, Katja; Lipinski, Martin; Preuten, Marius; Schomakers, Christian; Schulz, Johannes; Verlage, Tobias; Albert, Andreas; Brodski, Michael; Dietz-Laursonn, Erik; Duchardt, Deborah; Endres, Matthias; Erdmann, Martin; Erdweg, Sören; Esch, Thomas; Fischer, Robert; Güth, Andreas; Hamer, Matthias; Hebbeker, Thomas; Heidemann, Carsten; Hoepfner, Kerstin; Knutzen, Simon; Merschmeyer, Markus; Meyer, Arnd; Millet, Philipp; Mukherjee, Swagata; Olschewski, Mark; Padeken, Klaas; Pook, Tobias; Radziej, Markus; Reithler, Hans; Rieger, Marcel; Scheuch, Florian; Sonnenschein, Lars; Teyssier, Daniel; Thüer, Sebastian; Cherepanov, Vladimir; Flügge, Günter; Kargoll, Bastian; Kress, Thomas; Künsken, Andreas; Lingemann, Joschka; Müller, Thomas; Nehrkorn, Alexander; Nowack, Andreas; Pistone, Claudia; Pooth, Oliver; Stahl, Achim; Aldaya Martin, Maria; Arndt, Till; Asawatangtrakuldee, Chayanit; Beernaert, Kelly; Behnke, Olaf; Behrens, Ulf; Bin Anuar, Afiq Aizuddin; Borras, Kerstin; Campbell, Alan; Connor, Patrick; Contreras-Campana, Christian; Costanza, Francesco; Diez Pardos, Carmen; Dolinska, Ganna; Eckerlin, Guenter; Eckstein, Doris; Eichhorn, Thomas; Eren, Engin; Gallo, Elisabetta; Garay Garcia, Jasone; Geiser, Achim; Gizhko, Andrii; Grados Luyando, Juan Manuel; Grohsjean, Alexander; Gunnellini, Paolo; Harb, Ali; Hauk, Johannes; Hempel, Maria; Jung, Hannes; Kalogeropoulos, Alexis; Karacheban, Olena; Kasemann, Matthias; Keaveney, James; Kleinwort, Claus; Korol, Ievgen; Krücker, Dirk; Lange, Wolfgang; Lelek, Aleksandra; Lenz, Teresa; Leonard, Jessica; Lipka, Katerina; Lobanov, Artur; Lohmann, Wolfgang; Mankel, Rainer; Melzer-Pellmann, Isabell-Alissandra; Meyer, Andreas Bernhard; Mittag, Gregor; Mnich, Joachim; Mussgiller, Andreas; Pitzl, Daniel; Placakyte, Ringaile; Raspereza, Alexei; Roland, Benoit; Sahin, Mehmet Özgür; Saxena, Pooja; Schoerner-Sadenius, Thomas; Spannagel, Simon; Stefaniuk, Nazar; Van Onsem, Gerrit Patrick; Walsh, Roberval; Wissing, Christoph; Zenaiev, Oleksandr; Blobel, Volker; Centis Vignali, Matteo; Draeger, Arne-Rasmus; Dreyer, Torben; Garutti, Erika; Gonzalez, Daniel; Haller, Johannes; Hoffmann, Malte; Junkes, Alexandra; Klanner, Robert; Kogler, Roman; Kovalchuk, Nataliia; Kurz, Simon; Lapsien, Tobias; Marchesini, Ivan; Marconi, Daniele; Meyer, Mareike; Niedziela, Marek; Nowatschin, Dominik; Pantaleo, Felice; Peiffer, Thomas; Perieanu, Adrian; Scharf, Christian; Schleper, Peter; Schmidt, Alexander; Schumann, Svenja; Schwandt, Joern; Sonneveld, Jory; Stadie, Hartmut; Steinbrück, Georg; Stober, Fred-Markus Helmut; Stöver, Marc; Tholen, Heiner; Troendle, Daniel; Usai, Emanuele; Vanelderen, Lukas; Vanhoefer, Annika; Vormwald, Benedikt; Akbiyik, Melike; Barth, Christian; Baur, Sebastian; Baus, Colin; Berger, Joram; Butz, Erik; Caspart, René; Chwalek, Thorsten; Colombo, Fabio; De Boer, Wim; Dierlamm, Alexander; Fink, Simon; Freund, Benedikt; Friese, Raphael; Giffels, Manuel; Gilbert, Andrew; Goldenzweig, Pablo; Haitz, Dominik; Hartmann, Frank; Heindl, Stefan Michael; Husemann, Ulrich; Kassel, Florian; Katkov, Igor; Kudella, Simon; Mildner, Hannes; Mozer, Matthias Ulrich; Müller, Thomas; Plagge, Michael; Quast, Gunter; Rabbertz, Klaus; Röcker, Steffen; Roscher, Frank; Schröder, Matthias; Shvetsov, Ivan; Sieber, Georg; Simonis, Hans-Jürgen; Ulrich, Ralf; Wayand, Stefan; Weber, Marc; Weiler, Thomas; Williamson, Shawn; Wöhrmann, Clemens; Wolf, Roger; Anagnostou, Georgios; Daskalakis, Georgios; Geralis, Theodoros; Giakoumopoulou, Viktoria Athina; Kyriakis, Aristotelis; Loukas, Demetrios; Topsis-Giotis, Iasonas; Kesisoglou, Stilianos; Panagiotou, Apostolos; Saoulidou, Niki; Tziaferi, Eirini; Kousouris, Konstantinos; Evangelou, Ioannis; Flouris, Giannis; Foudas, Costas; Kokkas, Panagiotis; Loukas, Nikitas; Manthos, Nikolaos; Papadopoulos, Ioannis; Paradas, Evangelos; Filipovic, Nicolas; Pasztor, Gabriella; Bencze, Gyorgy; Hajdu, Csaba; Horvath, Dezso; Sikler, Ferenc; Veszpremi, Viktor; Vesztergombi, Gyorgy; Zsigmond, Anna Julia; Beni, Noemi; Czellar, Sandor; Karancsi, János; Makovec, Alajos; Molnar, Jozsef; Szillasi, Zoltan; Bartók, Márton; Raics, Peter; Trocsanyi, Zoltan Laszlo; Ujvari, Balazs; Komaragiri, Jyothsna Rani; Bahinipati, Seema; Bhowmik, Sandeep; Choudhury, Somnath; Mal, Prolay; Mandal, Koushik; Nayak, Aruna; Sahoo, Deepak Kumar; Sahoo, Niladribihari; Swain, Sanjay Kumar; Bansal, Sunil; Beri, Suman Bala; Bhatnagar, Vipin; Chawla, Ridhi; Bhawandeep, Bhawandeep; Kalsi, Amandeep Kaur; Kaur, Anterpreet; Kaur, Manjit; Kumar, Ramandeep; Kumari, Priyanka; Mehta, Ankita; Mittal, Monika; Singh, Jasbir; Walia, Genius; Kumar, Ashok; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Garg, Rocky Bala; Keshri, Sumit; Kumar, Ajay; Malhotra, Shivali; Naimuddin, Md; Ranjan, Kirti; Sharma, Ramkrishna; Sharma, Varun; Bhattacharya, Rajarshi; Bhattacharya, Satyaki; Chatterjee, Kalyanmoy; Dey, Sourav; Dutt, Suneel; Dutta, Suchandra; Ghosh, Shamik; Majumdar, Nayana; Modak, Atanu; Mondal, Kuntal; Mukhopadhyay, Supratik; Nandan, Saswati; Purohit, Arnab; Roy, Ashim; Roy, Debarati; Roy Chowdhury, Suvankar; Sarkar, Subir; Sharan, Manoj; Thakur, Shalini; Behera, Prafulla Kumar; Chudasama, Ruchi; Dutta, Dipanwita; Jha, Vishwajeet; Kumar, Vineet; Mohanty, Ajit Kumar; Netrakanti, Pawan Kumar; Pant, Lalit Mohan; Shukla, Prashant; Topkar, Anita; Aziz, Tariq; Dugad, Shashikant; Kole, Gouranga; Mahakud, Bibhuprasad; Mitra, Soureek; Mohanty, Gagan Bihari; Parida, Bibhuti; Sur, Nairit; Sutar, Bajrang; Banerjee, Sudeshna; Dewanjee, Ram Krishna; Ganguly, Sanmay; Guchait, Monoranjan; Jain, Sandhya; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Sarkar, Tanmay; Wickramage, Nadeesha; Chauhan, Shubhanshu; Dube, Sourabh; Hegde, Vinay; Kapoor, Anshul; Kothekar, Kunal; Pandey, Shubham; Rane, Aditee; Sharma, Seema; Chenarani, Shirin; Eskandari Tadavani, Esmaeel; Etesami, Seyed Mohsen; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Paktinat Mehdiabadi, Saeid; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Caputo, Claudio; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Fiore, Luigi; Iaselli, Giuseppe; Maggi, Giorgio; Maggi, Marcello; Miniello, Giorgia; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Ranieri, Antonio; Selvaggi, Giovanna; Sharma, Archana; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Abbiendi, Giovanni; Battilana, Carlo; Bonacorsi, Daniele; Braibant-Giacomelli, Sylvie; Brigliadori, Luca; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Chhibra, Simranjit Singh; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Fasanella, Daniele; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Albergo, Sebastiano; Costa, Salvatore; Di Mattia, Alessandro; Giordano, Ferdinando; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Russo, Lorenzo; Sguazzoni, Giacomo; Strom, Derek; Viliani, Lorenzo; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Primavera, Federica; Calvelli, Valerio; Ferro, Fabrizio; Monge, Maria Roberta; Robutti, Enrico; Tosi, Silvano; Brianza, Luca; Brivio, Francesco; Ciriolo, Vincenzo; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Malberti, Martina; Malvezzi, Sandra; Manzoni, Riccardo Andrea; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Pigazzini, Simone; Ragazzi, Stefano; Tabarelli de Fatis, Tommaso; Buontempo, Salvatore; Cavallo, Nicola; De Nardo, Guglielmo; Di Guida, Salvatore; Esposito, Marco; Fabozzi, Francesco; Fienga, Francesco; Iorio, Alberto Orso Maria; Lanza, Giuseppe; Lista, Luca; Meola, Sabino; Paolucci, Pierluigi; Sciacca, Crisostomo; Thyssen, Filip; Azzi, Patrizia; Bacchetta, Nicola; Benato, Lisa; Bisello, Dario; Boletti, Alessio; Carlin, Roberto; Carvalho Antunes De Oliveira, Alexandra; Checchia, Paolo; Dall'Osso, Martino; De Castro Manzano, Pablo; Dorigo, Tommaso; Dosselli, Umberto; Gasparini, Ugo; Gonella, Franco; Lacaprara, Stefano; Margoni, Martino; Meneguzzo, Anna Teresa; Pazzini, Jacopo; Pozzobon, Nicola; Ronchese, Paolo; Rossin, Roberto; Simonetto, Franco; Torassa, Ezio; Ventura, Sandro; Zanetti, Marco; Zotto, Pierluigi; Braghieri, Alessandro; Fallavollita, Francesco; Magnani, Alice; Montagna, Paolo; Ratti, Sergio P; Re, Valerio; Ressegotti, Martina; Riccardi, Cristina; Salvini, Paola; Vai, Ilaria; Vitulo, Paolo; Alunni Solestizi, Luisa; Bilei, Gian Mario; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Leonardi, Roberto; Mantovani, Giancarlo; Mariani, Valentina; Menichelli, Mauro; Saha, Anirban; Santocchia, Attilio; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bernardini, Jacopo; Boccali, Tommaso; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Fedi, Giacomo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Lomtadze, Teimuraz; Martini, Luca; Messineo, Alberto; Palla, Fabrizio; Rizzi, Andrea; Savoy-Navarro, Aurore; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Cipriani, Marco; Del Re, Daniele; Diemoz, Marcella; Gelli, Simone; Longo, Egidio; Margaroli, Fabrizio; Marzocchi, Badder; Meridiani, Paolo; Organtini, Giovanni; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Costa, Marco; Covarelli, Roberto; Degano, Alessandro; Demaria, Natale; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Monteno, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Ravera, Fabio; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Staiano, Amedeo; Traczyk, Piotr; Belforte, Stefano; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Jeongeun; Lee, Sangeun; Lee, Seh Wook; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Lee, Ari; Kim, Hyunchul; Brochero Cifuentes, Javier Andres; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Kim, Yongsun; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Almond, John; Kim, Junho; Lee, Haneol; Oh, Sung Bin; Radburn-Smith, Benjamin Charles; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Choi, Minkyoo; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Ryu, Geonmo; Ryu, Min Sang; Choi, Young-Il; Goh, Junghwan; Hwang, Chanwook; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Heredia-De La Cruz, Ivan; Lopez-Fernandez, Ricardo; Magaña Villalba, Ricardo; Mejia Guisao, Jhovanny; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Carpinteyro, Severiano; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Hassan, Qamar; Hoorani, Hafeez R; Khan, Wajid Ali; Saddique, Asif; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bożena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Romanowska-Rybinska, Katarzyna; Szleper, Michal; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Pyskir, Andrzej; Walczak, Marek; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Calpas, Betty; Di Francesco, Agostino; Faccioli, Pietro; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Lloret Iglesias, Lara; Nemallapudi, Mythra Varun; Seixas, Joao; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Afanasiev, Serguei; Bunin, Pavel; Gavrilenko, Mikhail; Golutvin, Igor; Gorbunov, Ilya; Kamenev, Alexey; Karjavin, Vladimir; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Shulha, Siarhei; Skatchkov, Nikolai; Smirnov, Vitaly; Voytishin, Nikolay; Zarubin, Anatoli; Chtchipounov, Leonid; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Murzin, Victor; Oreshkin, Vadim; Sulimov, Valentin; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Aushev, Tagir; Bylinkin, Alexander; Danilov, Mikhail; Popova, Elena; Rusinov, Vladimir; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Bunichev, Viacheslav; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Klyukhin, Vyacheslav; Korneeva, Natalia; Lokhtin, Igor; Miagkov, Igor; Obraztsov, Stepan; Perfilov, Maxim; Savrin, Viktor; Volkov, Petr; Blinov, Vladimir; Skovpen, Yuri; Shtol, Dmitry; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Dordevic, Milos; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Barrio Luna, Mar; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Navarro De Martino, Eduardo; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; de Trocóniz, Jorge F; Missiroli, Marino; Moran, Dermot; Cuevas, Javier; Erice, Carlos; Fernandez Menendez, Javier; Gonzalez Caballero, Isidro; González Fernández, Juan Rodrigo; Palencia Cortezon, Enrique; Sanchez Cruz, Sergio; Suárez Andrés, Ignacio; Vischia, Pietro; Vizan Garcia, Jesus Manuel; Cabrillo, Iban Jose; Calderon, Alicia; Curras, Esteban; Fernandez, Marcos; Garcia-Ferrero, Juan; Gomez, Gervasio; Lopez Virto, Amparo; Marco, Jesus; Martinez Rivero, Celso; Matorras, Francisco; Piedra Gomez, Jonatan; Rodrigo, Teresa; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Trevisani, Nicolò; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Baillon, Paul; Ball, Austin; Barney, David; Bloch, Philippe; Bocci, Andrea; Botta, Cristina; Camporesi, Tiziano; Castello, Roberto; Cepeda, Maria; Cerminara, Gianluca; Chen, Yi; Cimmino, Anna; D'Enterria, David; Dabrowski, Anne; Daponte, Vincenzo; David Tinoco Mendes, Andre; De Gruttola, Michele; De Roeck, Albert; Di Marco, Emanuele; Dobson, Marc; Dorney, Brian; Du Pree, Tristan; Duggan, Daniel; Dünser, Marc; Dupont, Niels; Elliott-Peisert, Anna; Everaerts, Pieter; Fartoukh, Stephane; Franzoni, Giovanni; Fulcher, Jonathan; Funk, Wolfgang; Gigi, Dominique; Gill, Karl; Girone, Maria; Glege, Frank; Gulhan, Doga; Gundacker, Stefan; Guthoff, Moritz; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Kieseler, Jan; Kirschenmann, Henning; Knünz, Valentin; Kornmayer, Andreas; Kortelainen, Matti J; Krammer, Manfred; Lange, Clemens; Lecoq, Paul; Lourenco, Carlos; Lucchini, Marco Toliman; Malgeri, Luca; Mannelli, Marcello; Martelli, Arabella; Meijers, Frans; Merlin, Jeremie Alexandre; Mersi, Stefano; Meschi, Emilio; Milenovic, Predrag; Moortgat, Filip; Morovic, Srecko; Mulders, Martijn; Neugebauer, Hannes; Orfanelli, Styliani; Orsini, Luciano; Pape, Luc; Perez, Emmanuel; Peruzzi, Marco; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Racz, Attila; Reis, Thomas; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Sauvan, Jean-Baptiste; Schäfer, Christoph; Schwick, Christoph; Seidel, Markus; Sharma, Archana; Silva, Pedro; Sphicas, Paraskevas; Steggemann, Jan; Stoye, Markus; Takahashi, Yuta; Tosi, Mia; Treille, Daniel; Triossi, Andrea; Tsirou, Andromachi; Veckalns, Viesturs; Veres, Gabor Istvan; Verweij, Marta; Wardle, Nicholas; Wöhri, Hermine Katharina; Zagoździńska, Agnieszka; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Rohe, Tilman; Wiederkehr, Stephan Albert; Bachmair, Felix; Bäni, Lukas; Bianchini, Lorenzo; Casal, Bruno; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Grab, Christoph; Heidegger, Constantin; Hits, Dmitry; Hoss, Jan; 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Zhang, Jingyu; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Durgut, Süleyman; Gandrajula, Reddy Pratap; Haytmyradov, Maksat; Khristenko, Viktor; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Snyder, Christina; Tiras, Emrah; Wetzel, James; Yi, Kai; Blumenfeld, Barry; Cocoros, Alice; Eminizer, Nicholas; Fehling, David; Feng, Lei; Gritsan, Andrei; Maksimovic, Petar; Roskes, Jeffrey; Sarica, Ulascan; Swartz, Morris; Xiao, Meng; You, Can; Al-bataineh, Ayman; Baringer, Philip; Bean, Alice; Boren, Samuel; Bowen, James; Castle, James; Forthomme, Laurent; Khalil, Sadia; Kropivnitskaya, Anna; Majumder, Devdatta; Mcbrayer, William; Murray, Michael; Sanders, Stephen; Stringer, Robert; Tapia Takaki, Daniel; Wang, Quan; Ivanov, Andrew; Kaadze, Ketino; Maravin, Yurii; Mohammadi, Abdollah; Saini, Lovedeep Kaur; Skhirtladze, Nikoloz; Toda, Sachiko; Rebassoo, Finn; Wright, Douglas; Anelli, Christopher; 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Wang, Ta-Wei; Wyslouch, Bolek; Benvenuti, Alberto; Chatterjee, Rajdeep Mohan; Evans, Andrew; Hansen, Peter; Kalafut, Sean; Kao, Shih-Chuan; Kubota, Yuichi; Lesko, Zachary; Mans, Jeremy; Nourbakhsh, Shervin; Ruckstuhl, Nicole; Rusack, Roger; Tambe, Norbert; Turkewitz, Jared; Acosta, John Gabriel; Oliveros, Sandra; Avdeeva, Ekaterina; Bloom, Kenneth; Claes, Daniel R; Fangmeier, Caleb; Gonzalez Suarez, Rebeca; Kamalieddin, Rami; Kravchenko, Ilya; Malta Rodrigues, Alan; Monroy, Jose; Siado, Joaquin Emilo; Snow, Gregory R; Stieger, Benjamin; Alyari, Maral; Dolen, James; Godshalk, Andrew; Harrington, Charles; Iashvili, Ia; Kaisen, Josh; Nguyen, Duong; Parker, Ashley; Rappoccio, Salvatore; Roozbahani, Bahareh; Alverson, George; Barberis, Emanuela; Hortiangtham, Apichart; Massironi, Andrea; Morse, David Michael; Nash, David; Orimoto, Toyoko; Teixeira De Lima, Rafael; Trocino, Daniele; Wang, Ren-Jie; Wood, Darien; Bhattacharya, Saptaparna; Charaf, Otman; Hahn, Kristan Allan; Mucia, Nicholas; Odell, Nathaniel; 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Sheffield, David; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Delannoy, Andrés G; Foerster, Mark; Heideman, Joseph; Riley, Grant; Rose, Keith; Spanier, Stefan; Thapa, Krishna; Bouhali, Othmane; Celik, Ali; Dalchenko, Mykhailo; De Mattia, Marco; Delgado, Andrea; Dildick, Sven; Eusebi, Ricardo; Gilmore, Jason; Huang, Tao; Juska, Evaldas; Kamon, Teruki; Mueller, Ryan; Pakhotin, Yuriy; Patel, Rishi; Perloff, Alexx; Perniè, Luca; Rathjens, Denis; Safonov, Alexei; Tatarinov, Aysen; Ulmer, Keith; Akchurin, Nural; Damgov, Jordan; De Guio, Federico; Dragoiu, Cosmin; Dudero, Phillip Russell; Faulkner, James; Gurpinar, Emine; Kunori, Shuichi; Lamichhane, Kamal; Lee, Sung Won; Libeiro, Terence; Peltola, Timo; Undleeb, Sonaina; Volobouev, Igor; Wang, Zhixing; Greene, Senta; Gurrola, Alfredo; Janjam, Ravi; Johns, Willard; Maguire, Charles; Melo, Andrew; Ni, Hong; Sheldon, Paul; Tuo, Shengquan; Velkovska, Julia; Xu, Qiao; Arenton, Michael Wayne; Barria, Patrizia; Cox, Bradley; Hirosky, Robert; Ledovskoy, Alexander; Li, Hengne; Neu, Christopher; Sinthuprasith, Tutanon; Sun, Xin; Wang, Yanchu; Wolfe, Evan; Xia, Fan; Clarke, Christopher; Harr, Robert; Karchin, Paul Edmund; Sturdy, Jared; Zaleski, Shawn; Belknap, Donald; Buchanan, James; Caillol, Cécile; Dasu, Sridhara; Dodd, Laura; Duric, Senka; Gomber, Bhawna; Grothe, Monika; Herndon, Matthew; Hervé, Alain; Hussain, Usama; Klabbers, Pamela; Lanaro, Armando; Levine, Aaron; Long, Kenneth; Loveless, Richard; Pierro, Giuseppe Antonio; Polese, Giovanni; Ruggles, Tyler; Savin, Alexander; Smith, Nicholas; Smith, Wesley H; Taylor, Devin; Woods, Nathaniel

    2017-01-01

    Normalized double-differential cross sections for top quark pair ($ \\mathrm{ t \\bar{t} } $) production are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7 fb$^{-1}$. The measurement is performed in the dilepton $\\mathrm{ e }^{\\pm}\\mu^{\\mp}$ final state. The $ \\mathrm{ t \\bar{t} } $ cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and $ \\mathrm{ t \\bar{t} } $ system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions ar...

  12. Jet Quenching with Parton evolution

    CERN Document Server

    Cheng, Luan

    2009-01-01

    We report the evolution effects on jet energy loss with detailed balance. The initial conditions and parton evolution based on perturbative QCD in the chemical non-equilibrated medium and Bjorken expanding medium at RHIC are determined. The parton evolution affect the jet energy loss evidently. This will increase the energy and propagating distance dependence of the parton energy loss and will affect the shape of suppression of moderately high P_{T} hadron spectra.

  13. The Distributed Nature of Pattern Generalization

    Science.gov (United States)

    Rivera, Ferdinand

    2015-01-01

    Drawing on a review of recent work conducted in the area of pattern generalization (PG), this paper makes a case for a distributed view of PG, which basically situates processing ability in terms of convergences among several different factors that influence PG. Consequently, the distributed nature leads to different types of PG that depend on the…

  14. Similarity of parton and hadron spectra in QCD jets

    Energy Technology Data Exchange (ETDEWEB)

    Azimov, Ya.I.; Dokshitzer, Yu.L.; Khoze, V.A.; Troyan, S.I.

    1985-02-01

    A possible existence of the local correspondence between parton and hadron distributions in hard processes (local parton-hadron duality) is discussed. First comparison is made to check up local duality at modern energies. It is shown, in particular, that an account of essential single-logarithmic corrections to leading double-logarithmic approximation proves sufficient to fit ..pi..sup(+-) spectra in e/sup +/e/sup -/ annihilation at W> or approx.20 GeV by theoretical perturbative spectra of QCD partons. Rapidity spectra versus the normalized rapidity appear to be similar for ..pi.., K, p. Further tests of local duality as well as effects of chromodynamical coherence are suggested.

  15. What is Double Parton Scattering?

    CERN Document Server

    Manohar, Aneesh V

    2012-01-01

    Processes such as double Drell-Yan and same-sign WW production have contributions from double parton scattering, which are not well-defined because of a delta(z_\\perp=0) singularity that is generated by QCD evolution. We study the single and double parton contributions to these processes, and show how to handle the singularity using factorization and operator renormalization.

  16. Parton energy loss in glasma

    Energy Technology Data Exchange (ETDEWEB)

    Aurenche, P. [LAPTH, Universite de Savoie, CNRS, BP 110, F-74941, Annecy-le-Vieux Cedex (France); Zakharov, B.G. [L.D. Landau Institute for Theoretical Physics, GSP-1, 117940, Kosygina Str. 2, 117334 Moscow (Russian Federation)

    2013-01-08

    We study the synchrotron-like gluon emission in AA-collisions from fast partons due to interaction with the coherent glasma color fields. Our results show that for RHIC and LHC conditions the contribution of this mechanism to parton energy loss is much smaller than the radiative energy loss in the plasma phase.

  17. Transmuted New Generalized Inverse Weibull Distribution

    Directory of Open Access Journals (Sweden)

    Muhammad Shuaib Khan

    2017-06-01

    Full Text Available This paper introduces the transmuted new generalized inverse Weibull distribution by using the quadratic rank transmutation map (QRTM scheme studied by Shaw et al. (2007. The proposed model contains the twenty three lifetime distributions as special sub-models. Some mathematical properties of the new distribution are formulated, such as quantile function, Rényi entropy, mean deviations, moments, moment generating function and order statistics. The method of maximum likelihood is used for estimating the model parameters. We illustrate the flexibility and potential usefulness of the new distribution by using reliability data.

  18. Inclusive parton cross sections in photoproduction and photon structure

    CERN Document Server

    Ahmed, T; Andrieu, B; Appuhn, R D; Arpagaus, M; Aïd, S; Babaev, A; Ban, Y; Baranov, P S; Barrelet, E; Bartel, Wulfrin; Barth, Monique; Bassler, U; Beck, H P; Behrend, H J; Belousov, A; Berger, C; Bergstein, H; Bernardi, G; Bernet, R; Bertrand-Coremans, G H; Besançon, M; Beyer, R; Biddulph, P; Bispham, P; Bizot, J C; Blobel, Volker; Borras, K; Botterweck, F; Boudry, V; Braemer, A; Brasse, F W; Braunschweig, W; Brisson, V; Bruncko, Dusan; Brune, C R; Buchholz, R; Buniatian, A Yu; Burke, S; Burton, M; Buschhorn, G W; Bán, J; Bähr, J; Büngener, L; Bürger, J; Büsser, F W; Campbell, A J; Carli, T; Charles, F; Charlet, M; Chernyshov, V; Clarke, D; Clegg, A B; Clerbaux, B; Colombo, M G; Contreras, J G; Cormack, C; Coughlan, J A; Courau, A; Coutures, C; Cozzika, G; Criegee, L; Cussans, D G; Cvach, J; Dagoret, S; Dainton, J B; Dau, W D; Daum, K; David, M; De Wolf, E A; Del Buono, L; Delcourt, B; Di Nezza, P; Dollfus, C; Dowell, John D; Dreis, H B; Droutskoi, A; Duboc, J; Duhm, H; Düllmann, D; Dünger, O; Ebert, J; Ebert, T R; Eckerlin, G; Efremenko, V; Egli, S; Eichenberger, S; Eichler, R; Eisele, Franz; Eisenhandler, Eric F; Ellison, R J; Elsen, E E; Erdmann, M; Erdmann, W; Erlichmann, H; Evrard, E; Favart, L; Fedotov, A; Feeken, D; Felst, R; Feltesse, Joel; Ferencei, J; Ferrarotto, F; Flamm, K; Fleischer, M; Flieser, M; Flügge, G; Fomenko, A; Fominykh, B A; Forbush, M; Formánek, J; Foster, J M; Franke, G; Fretwurst, E; Gabathuler, Erwin; Gabathuler, K; Gamerdinger, K; Garvey, J; Gayler, J; Gebauer, M; Gellrich, A; Genzel, H; Gerhards, R; Goerlach, U; Gogitidze, N; Goldberg, M; Goldner, D; González-Pineiro, B; Gorelov, I V; Goritchev, P A; Grab, C; Greenshaw, T J; Grindhammer, G; Gruber, A; Gruber, C; Grässler, Herbert; Grässler, R; Görlich, L; Haack, J; Haidt, Dieter; Hajduk, L; Hamon, O; Hampel, M; Hanlon, E M; Hapke, M; Haynes, W J; Heatherington, J; Heinzelmann, G; Henderson, R C W; Henschel, H; Herynek, I; Hess, M F; Hildesheim, W; Hill, P; Hiller, K H; Hilton, C D; Hladky, J; Hoeger, K C; Horisberger, R P; Hudgson, V L; Huet, Patrick; Hufnagel, H; Höppner, M; Hütte, M; Ibbotson, M; Itterbeck, H; Jabiol, M A; Jacholkowska, A; Jacobsson, C; Jaffré, M; Janoth, J; Jansen, T; Johnson, D P; Johnson, L; Jung, H; Jönsson, L B; Kalmus, Peter I P; Kant, D; Kaschowitz, R; Kasselmann, P; Kathage, U; Katzy, J M; Kaufmann, H H; Kazarian, S; Kenyon, Ian Richard; Kermiche, S; Keuker, C; Kiesling, C; Klein, M; Kleinwort, C; Knies, G; Ko, W; Kolanoski, H; Kole, F; Kolya, S D; Korbel, V; Korn, M; Kostka, P; Kotelnikov, S K; Krasny, M W; Krehbiel, H; Krämerkämper, T; Krücker, D; Krüger, U P; Krüner-Marquis, U; Kubenka, J P; Kuhlen, M; Kurca, T; Kurzhöfer, J; Kuznik, B; Köhler, T; Köhne, J H; Küster, H; Lacour, D; Lamarche, F; Lander, R; Landon, M P J; Lange, W; Lanius, P; Laporte, J F; Lebedev, A; Leverenz, C; Levonian, S; Ley, C; Lindner, A; Lindström, G; Link, J; Linsel, F; Lipinski, J; List, B; Lobo, G; Loch, P; Lohmander, H; Lomas, J W; Lubimov, V; López, G C; Lüke, D; Magnussen, N; Malinovskii, E I; Mani, S; Maracek, R; Marage, P; Marks, J; Marshall, R; Martens, J; Martin, R D; Martyn, H U; Martyniak, J; Masson, S; Mavroidis, A; Maxfield, S J; McMahon, S J; Mehta, A; Meier, K; Mercer, D; Merz, T; Meyer, C A; Meyer, H; Meyer, J; Migliori, A; Mikocki, S; Milstead, D; Moreau, F; Morris, J V; Mroczko, E; Murín, P; Müller, G; Müller, K; Nagovitsin, V; Nahnhauer, R; Naroska, Beate; Naumann, T; Newman, P R; Newton, D; Neyret, D; Nguyen, H K; Nicholls, T C; Niebergall, F; Niebuhr, C B; Niedzballa, C; Nisius, R; Nowak, G; Noyes, G W; Nyberg-Werther, M; Oakden, M N; Oberlack, H; Obrock, U; Olsson, J E; Ozerov, D; Panaro, E; Panitch, A; Pascaud, C; Patel, G D; Peppel, E; Phillips, J P; Pichler, C; Pieuchot, A; Pitzl, D; Pope, G; Prell, S; Prosi, R; Pérez, E; Rabbertz, K; Raupach, F; Reimer, P; Reinshagen, S; Ribarics, P; Rick, Hartmut; Riech, V; Riedlberger, J; Riess, S; Rietz, M; Rizvi, E; Robertson, S M; Robmann, P; Roloff, H E; Roosen, R; Rosenbauer, K; Rostovtsev, A A; Rouse, F; Royon, C; Rusakov, S V; Rybicki, K; Rylko, R; Rädel, G; Rüter, K; Sahlmann, N; Salesch, S G; Sankey, D P C; Schacht, P; Schiek, S; Schleper, P; Schmidt, C; Schmidt, D; Schmidt, G; Schröder, V; Schuhmann, E; Schwab, B; Schwind, A; Schöning, A; Sefkow, F; Seidel, M; Sell, R; Semenov, A A; Shekelian, V I; Shevyakov, I; Shooshtari, H; Shtarkov, L N; Siegmon, G; Siewert, U; Sirois, Y; Skillicorn, Ian O; Smirnov, P; Smith, J R; Solochenko, V; Soloviev, Yu V; Spiekermann, J; Spielman, S; Spitzer, H; Starosta, R; Steenbock, M; Steffen, P; Steinberg, R; Stella, B; Stephens, K; Stier, J; Stiewe, J; Stolze, K; Strachota, J; Straumann, U; Struczinski, W; Stösslein, U; Sutton, J P; Sánchez, E; Tapprogge, Stefan; Thiebaux, C; Thompson, G; Truöl, P; Turnau, J; Tutas, J; Uelkes, P; Usik, A; Valkár, S; Valkárová, A; Vallée, C; Van Esch, P; Van Mechelen, P; Vartapetian, A H; Vazdik, Ya A; Verrecchia, P; Villet, G; Wacker, K; Wagener, A; Wagener, M; Walker, I W; Walther, A; Weber, G; Weber, M; Wegener, D; Wegner, A; Wellisch, H P; West, L R; Willard, S; Winde, M; Winter, G G; Wittek, C; Wright, A E; Wulff, N; Wünsch, E; Yiou, T P; Zarbock, D; Zhang, Z; Zhokin, A S; Zimmer, M; Zimmermann, W; Zomer, F; Zuber, K; Zácek, J; de Roeck, A; von Schlippe, W

    1995-01-01

    Photoproduction of 2-jet events is studied with the H1 detector at HERA. Parton cross sections are extracted from the data by an unfolding method using leading order parton-jet correlations of a QCD generator. The gluon distribution in the photon is derived in the fractional momentum range 0.04\\le x_\\gamma \\le 1 at the average factorization scale 75 GeV^2.

  19. Wee partons in large nuclei: From virtual dream to hard reality

    Energy Technology Data Exchange (ETDEWEB)

    Venugopalan, R.

    1995-06-01

    We construct a weak coupling, many body theory to compute parton distributions in large nuclei for x {much_lt} A{sup {minus} 1/3}. The wee partons are highly coherent, non-Abelian Weizsaecker-Williams fields. Radiative corrections to the classical results axe discussed. The parton distributions for a single nucleus provide the initial conditions for the dynamical evolution of matter formed in ultrarelativistic nuclear collisions.

  20. Generalized Analysis of a Distribution Separation Method

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2016-04-01

    Full Text Available Separating two probability distributions from a mixture model that is made up of the combinations of the two is essential to a wide range of applications. For example, in information retrieval (IR, there often exists a mixture distribution consisting of a relevance distribution that we need to estimate and an irrelevance distribution that we hope to get rid of. Recently, a distribution separation method (DSM was proposed to approximate the relevance distribution, by separating a seed irrelevance distribution from the mixture distribution. It was successfully applied to an IR task, namely pseudo-relevance feedback (PRF, where the query expansion model is often a mixture term distribution. Although initially developed in the context of IR, DSM is indeed a general mathematical formulation for probability distribution separation. Thus, it is important to further generalize its basic analysis and to explore its connections to other related methods. In this article, we first extend DSM’s theoretical analysis, which was originally based on the Pearson correlation coefficient, to entropy-related measures, including the KL-divergence (Kullback–Leibler divergence, the symmetrized KL-divergence and the JS-divergence (Jensen–Shannon divergence. Second, we investigate the distribution separation idea in a well-known method, namely the mixture model feedback (MMF approach. We prove that MMF also complies with the linear combination assumption, and then, DSM’s linear separation algorithm can largely simplify the EM algorithm in MMF. These theoretical analyses, as well as further empirical evaluation results demonstrate the advantages of our DSM approach.

  1. Generalized binomial distribution in photon statistics

    Science.gov (United States)

    Ilyin, Aleksey

    2015-01-01

    The photon-number distribution between two parts of a given volume is found for an arbitrary photon statistics. This problem is related to the interaction of a light beam with a macroscopic device, for example a diaphragm, that separates the photon flux into two parts with known probabilities. To solve this problem, a Generalized Binomial Distribution (GBD) is derived that is applicable to an arbitrary photon statistics satisfying probability convolution equations. It is shown that if photons obey Poisson statistics then the GBD is reduced to the ordinary binomial distribution, whereas in the case of Bose- Einstein statistics the GBD is reduced to the Polya distribution. In this case, the photon spatial distribution depends on the phase-space volume occupied by the photons. This result involves a photon bunching effect, or collective behavior of photons that sharply differs from the behavior of classical particles. It is shown that the photon bunching effect looks similar to the quantum interference effect.

  2. Some properties of generalized gamma distribution

    Directory of Open Access Journals (Sweden)

    Morteza Khodabin

    2010-03-01

    Full Text Available In this paper, the generalized gamma (GG distribution that is a flexible distribution in statistical literature, and has exponential, gamma, and Weibull as subfamilies, and lognormal as a limiting distribution is introduced. The power and logarithmic moments of this family is defined. A new moment estimation method of parameters of GG family using it's characterization is presented, this method is compared with MLE method in gamma subfamily for small and large sample size. Here we study GG entropy representation and its estimation. In addition Kullback-Leibler discrimination , Akaike and Bayesian information criterion is discussed. In brief, this paper consist of presentation of general review of important properties in GG family.

  3. Fitting statistical distributions the generalized lambda distribution and generalized bootstrap methods

    CERN Document Server

    Karian, Zaven A

    2000-01-01

    Throughout the physical and social sciences, researchers face the challenge of fitting statistical distributions to their data. Although the study of statistical modelling has made great strides in recent years, the number and variety of distributions to choose from-all with their own formulas, tables, diagrams, and general properties-continue to create problems. For a specific application, which of the dozens of distributions should one use? What if none of them fit well?Fitting Statistical Distributions helps answer those questions. Focusing on techniques used successfully across many fields, the authors present all of the relevant results related to the Generalized Lambda Distribution (GLD), the Generalized Bootstrap (GB), and Monte Carlo simulation (MC). They provide the tables, algorithms, and computer programs needed for fitting continuous probability distributions to data in a wide variety of circumstances-covering bivariate as well as univariate distributions, and including situations where moments do...

  4. Double parton scattering in CMS

    CERN Document Server

    Sunar Cerci, Deniz

    2017-01-01

    Recent results on the double parton scattering measurements performed using the proton-proton collision data collected with the CMS detector are presented. The observables, which are sensitive to double parton scattering, are investigated after being corrected for detector effects and selection efficiencies. Multivariate analysis techniques are used for increasing the sensitivity. The effective cross section, $\\sigma_{eff}$ is also extracted using different processes at various center-of-mass energies.

  5. Brane Partons and Singleton Strings

    CERN Document Server

    Engquist, J

    2005-01-01

    We examine p-branes in AdS_D in two limits where they exhibit partonic behavior: rotating branes with energy concentrated to cusp-like solitons; tensionless branes with energy distributed over singletonic bits on the Dirac hypercone. Evidence for a smooth transition from cusps to bits are found. First, each cusp yields D-2 normal-coordinate bound states with protected frequencies; and is dual to a short open p-brane becoming massless on the giant-vacuum brane at the end-of-the-universe. Second, the N_{bit}-sector is an sp(2N_{bit})-gauged phase-space sigma model giving rise to symmetrized N_{bit}-pletons of the minimal higher-spin algebra ho_0(D-1,2)\\supset so(D-1,2). The continuum limit leads to a 2d chiral sp(2)-gauged sigma model which is critical in D=7; equivalent 'a la Bars-Vasiliev to an su(2)-gauged spinor string; and furthermore dual to WZW model in turn containing a topological \\hat{so}(6,2)_{-2}/(\\hat{so}(6)\\oplus\\hat{so}(2))_{-2} coset model giving rise to a chiral ring generated by singleton-valu...

  6. Generalized binomial distribution in photon statistics

    Directory of Open Access Journals (Sweden)

    Ilyin Aleksey

    2015-01-01

    Full Text Available The photon-number distribution between two parts of a given volume is found for an arbitrary photon statistics. This problem is related to the interaction of a light beam with a macroscopic device, for example a diaphragm, that separates the photon flux into two parts with known probabilities. To solve this problem, a Generalized Binomial Distribution (GBD is derived that is applicable to an arbitrary photon statistics satisfying probability convolution equations. It is shown that if photons obey Poisson statistics then the GBD is reduced to the ordinary binomial distribution, whereas in the case of Bose- Einstein statistics the GBD is reduced to the Polya distribution. In this case, the photon spatial distribution depends on the phase-space volume occupied by the photons. This result involves a photon bunching effect, or collective behavior of photons that sharply differs from the behavior of classical particles. It is shown that the photon bunching effect looks similar to the quantum interference effect.

  7. On a six-parameter generalized Burr XII distribution

    OpenAIRE

    A. K. Olapade

    2008-01-01

    In this paper, we derive a probability density function that generalizes the Burr XII distribution. The cumulative distribution function and the $n^{th}$ moment of the generalized distribution are obtained while the distribution of some order statistics of the distribution are established. A theorem that relate the new distribution to another statistical distribution is established.

  8. Impact Representation of Generalized Distribution Amplitudes

    CERN Document Server

    Pire, B

    2003-01-01

    We develop an impact representation for the generalized distribution amplitude which describes the exclusive hadronization of a quark-antiquark pair to a pair of mesons. Experiments such as gamma^* gamma -> pi pi and gamma^* N -> pi pi N' are shown to probe the transverse size of the hadronization region of the quark antiquark pair that one can interpret as the transverse overlap of the two emerging mesons. An astonishing feature of this description is that low energy pi pi phase shift analysis can be used for understanding some properties of quark hadronization process.

  9. Delineating the polarized and unpolarized partonic structure of the nucleon

    CERN Document Server

    Jimenez-Delgado, Pedro

    2014-01-01

    Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.

  10. Soft factors for double parton scattering at NNLO

    CERN Document Server

    Vladimirov, Alexey

    2016-01-01

    We show at NNLO that the soft factors for double parton scattering (DPS) for both integrated and unintegrated kinematics, can be presented entirely in the terms of the soft factor for single Drell-Yan process, i.e. the transverse momentum dependent (TMD) soft factor. Using the linearity of logarithm of TMD soft factor in rapidity divergences, we decompose the DPS soft factor matrices into a product of matrices with rapidity divergences in given sectors, and thus, define individual double parton distributions at NNLO. The rapidity anomalous dimension matrices for double parton distributions are presented in terms of TMD rapidity anomalous dimension. The analysis is done using the generating function approach to web diagrams. Significant part of the result is obtained from the symmetry properties of web diagrams without referring to explicit expressions or a particular rapidity regularization scheme. Additionally we present NNLO expression for the web diagram generating function for Wilson lines with two light-...

  11. Multiple Parton Interactions in Hadron Collisions and Diffraction

    CERN Document Server

    Lipari, Paolo

    2009-01-01

    Hadrons are composite objects made of quarks and gluons, and during a collision one can have several elementary interactions between the constituents. These elementary interactions, using an appropriate theoretical framework, can be related to the total and elastic cross sections. At high c.m. energy it also becomes possible to identify experimentally a high pt subset of the parton interactions and to study their multiplicity distribution. Predictions of the multiple interactions rates are difficult because in principle one needs to have a knowledge of the correlated Parton Distribution Functions that describe the probability to find simultaneously different partons in different elements of phase space. In this work we address this question and suggest a method to describe effectively the fluctuations in the instantaneous configuration of a colliding hadron. This problem is intimately related to the origin of the inelastic diffractive processes. We present a new method to include the diffractive cross section...

  12. Soft factors for double parton scattering at NNLO

    Energy Technology Data Exchange (ETDEWEB)

    Vladimirov, Alexey [Institut für Theoretische Physik, Universität Regensburg,D-93040 Regensburg (Germany)

    2016-12-13

    We show at NNLO that the soft factors for double parton scattering (DPS) for both integrated and unintegrated kinematics, can be presented entirely in the terms of the soft factor for single Drell-Yan process, i.e. the transverse momentum dependent (TMD) soft factor. Using the linearity of the logarithm of TMD soft factor in rapidity divergences, we decompose the DPS soft factor matrices into a product of matrices with rapidity divergences in given sectors, and thus, define individual double parton distributions at NNLO. The rapidity anomalous dimension matrices for double parton distributions are presented in the terms of TMD rapidity anomalous dimension. The analysis is done using the generating function approach to web diagrams. Significant part of the result is obtained from the symmetry properties of web diagrams without referring to explicit expressions or a particular rapidity regularization scheme. Additionally, we present NNLO expression for the web diagram generating function for Wilson lines with two light-like directions.

  13. Reconstructing parton densities at large fractional momenta

    CERN Document Server

    Bacchetta, Alessandro; Pasquini, Barbara; Xiong, Xiaonu

    2016-01-01

    Parton distribution functions (PDFs) are nonperturbative objects defined by nonlocal light-cone correlations. They cannot be computed directly from Quantum Chromodynamics (QCD). Using a standard lattice QCD approach, it is possible to compute moments of PDFs, which are matrix elements of local operators. Recently, an alternative approach has been proposed, based on the introduction of quasi-parton distribution functions (quasi-PDFs), which are matrix elements of equal-time spatial correlations and hence calculable on lattice. Quasi-PDFs approach standard PDFs in the limit of very large longitudinal proton momenta $P^z$. This limit is not attainable in lattice simulations, and quasi-PDFs fail to reproduce PDFs at high fractional longitudinal momenta. In this paper, we propose a method to improve the reconstruction of PDFs by combining information from quasi-PDFs and from the Mellin moments of regular PDFs. We test our method using the diquark spectator model for up and down valence distributions of both unpola...

  14. Multi-Parton Interactions at the LHC

    CERN Document Server

    Bartalini, P; Blok, B; Calucci, G; Corke, R; Diehl, M; Dokshitzer, Yu; Fano, L; Frankfurt, L; Gaunt, J R; Gieseke, S; Gustafson, G; Kar, D; Kom, C -H; Kulesza, A; Maina, E; Nagy, Z; Roehr, Ch; Siodmok, A; Schmelling, M; Stirling, W J; Strikman, M; Treleani, D

    2011-01-01

    We review the recent progress in the theoretical description and experimental observation of multiple parton interactions. Subjects covered include experimental measurements of minimum bias interactions 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.

  15. Measurement of Parton Distributions of Strange Quarks in the Nucleon from Charged-Kaon Production in Deep-Inelastic Scattering on the Deuteron

    CERN Document Server

    Airapetian, A; Akopov, Z; Andrus, A; Aschenauer, E C; Augustyniak, W; Avakian, R; Avetisian, A; Avetissian, E; Belostotskii, S; Bianchi, N; Blok, H P; Bttcher, H; Bonomo, C; Borisov, A; Brüll, A; Bryzgalov, V; Burns, J; Capiluppi, M; Capitani, G P; Cisbani, E; Ciullo, G; Contalbrigo, M; Dalpiaz, P F; Deconinck, W; De Leo, R; Demey, M; De Nardo, L; De Sanctis, E; Diefenthaler, M; Di Nezza, P; Dreschler, J; Düren, M; Ehrenfried, M; Elalaoui-Moulay, A; Elbakian, G; Ellinghaus, F; Elschenbroich, U; Fabbri, R; Fantoni, A; Felawka, L; Frullani, S; Funel, A; Gabbert, D; Gapienko, G; Gapienko, V; Garibaldi, F; Gavrilov, G; Karibian, V; Giordano, F; Gliske, S; Gregor, I M; Guler, H; Hadjidakis, C; Hasch, D; Hasegawa, T; Hesselink, W H A; Hill, G; Hillenbrand, A; Hoek, M; Holler, Y; Hommez, B; Hristova, I; Iarygin, G; Imazu, Y; Ivanilov, A; Izotov, A; Jackson, H E; Jgoun, A; Joosten, S; Kaiser, R; Keri, T; Kinney, E; Kiselev, A; Kobayashi, T; Kopytin, M; Korotkov, V; Kozlov, V; Kravchenko, P; Krivokhizhin, V G; Lagamba, L; Lamb, R; Lapikas, L; Lehmann, I; Lenisa, P; Liebing, P; Linden-Levy, L A; Lopez Ruiz, A; Lorenzon, W; Lu, S; Lu, X R; Ma, B Q; Mahon, D; Maiheu, B; Makins, N C R; Manfr, L; Mao, Y; Marianski, B; Marukyan, H; Mexner, V; Miller, C A; Miyachi, Y; Muccifora, V; Murray, M; Mussgiller, A; Nagaitsev, A; Nappi, E; Naryshkin, Yu; Nass, A; Negodaev, M; Nowak, W D; Osborne, A; Pappalardo, L L; Perez-Benito, R; Pickert, N; Raithel, M; Reggiani, D; Reimer, P E; Reischl, A; Reolon, A R; Riedl, C; Rith, K; Rock, S E; Rosner, G; Rostomyan, A; Rubacek, L; Rubin, J; Ryckbosch, D; Salomatin, Y; Sanjiev, I; Schäfer, A; Schnell, G; Schüler, K P; Seitz, B; Shearer, C; Shibata, T A; Shutov, V; Stancari, M; Statera, M; Steffens, E; Steijger, J J M; Stenzel, H; Stewart, J; Stinzing, F; Streit, J; Tait, P; Taroian, S; Tchuiko, B; Terkulov, A; Trzcinski, A; Tytgat, M; Vandenbroucke, A; Van der Nat, P B; van der Steenhoven, G; Van Haarlem, Y; van Hulse, C; Varanda, M; Veretennikov, D; Vikhrov, V; Vilardi, I; Vogel, C; Wang, S; Yaschenko, S; Ye, H; Ye, Y; Ye, Z; Yen, S; Yu, W; Zeiler, D; Zihlmann, B; Zupranski, P

    2008-01-01

    The momentum and helicity density distributions of the strange quark sea in the nucleon are obtained in leading order from charged-kaon production in deep-inelastic scattering on the deuteron. The distributions are extracted from spin-averaged K+/- multiplicities, and from K+/- and inclusive double-spin asymmetries for scattering of polarized positrons by a polarized deuterium target. The shape of the momentum distribution is softer than that of the average of the ubar and dbar quarks. In the region of measurement, the helicity distribution is zero within experimental uncertainties.

  16. Emergent phenomena and partonic structure in hadrons

    Directory of Open Access Journals (Sweden)

    Roberts Craig D.

    2017-01-01

    Full Text Available Modern facilities are poised to tackle fundamental questions within the Standard Model, aiming to reveal the nature of confinement, its relationship to dynamical chiral symmetry breaking (DCSB – the origin of visible mass – and the connection between these two, key emergent phenomena. There is strong evidence to suggest that they are intimately connected with the appearance of momentum-dependent masses for gluons and quarks in QCD, which are large in the infrared: mg ~ 500MeV and Mq ~ 350MeV. DCSB, expressed in the dynamical generation of a dressed-quark mass, has an enormous variety of verifiable consequences, including an enigmatic result that the properties of the (almost massless pion are the cleanest expression of the mechanism which is responsible for almost all the visible mass in the Universe. This contribution explains that these emergent phenomena are expressed with particular force in the partonic structure of hadrons, e.g. in valence-quark parton distribution amplitudes and functions, and, consequently, in numerous hadronic observables, so that we are now in a position to exhibit the consequences of confinement and DCSB in a wide range of hadron observables, opening the way to empirical verification of their expression in the Standard Model.

  17. Emergent phenomena and partonic structure in hadrons

    CERN Document Server

    Roberts, Craig D

    2016-01-01

    Modern facilities are poised to tackle fundamental questions within the Standard Model, aiming to reveal the nature of confinement, its relationship to dynamical chiral symmetry breaking (DCSB) - the origin of visible mass - and the connection between these two, key emergent phenomena. There is strong evidence to suggest that they are intimately connected with the appearance of momentum-dependent masses for gluons and quarks in QCD, which are large in the infrared: $m_g \\sim 500\\,$MeV and $M_q\\sim 350\\,$MeV. DCSB, expressed in the dynamical generation of a dressed-quark mass, has an enormous variety of verifiable consequences, including an enigmatic result that the properties of the (almost) massless pion are the cleanest expression of the mechanism which is responsible for almost all the visible mass in the Universe. This contribution explains that these emergent phenomena are expressed with particular force in the partonic structure of hadrons, e.g. in valence-quark parton distribution amplitudes and functi...

  18. Characterization through distributional properties of dual generalized order statistics

    Directory of Open Access Journals (Sweden)

    A.H. Khan

    2012-10-01

    Full Text Available Distributional properties of two non-adjacent dual generalized order statistics have been used to characterize distributions. Further, one sided contraction and dilation for the dual generalized order statistics are discussed and then the results are deduced for generalized order statistics, order statistics, lower record statistics, upper record statistics and adjacent dual generalized order statistics.

  19. Constraints on parton distribution functions and extraction of the strong coupling constant from the inclusive jet cross section in pp collisions at $\\sqrt{s}$ = 7 TeV

    CERN Document Server

    Khachatryan, Vardan; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Krätschmer, Ilse; Liko, Dietrich; Mikulec, Ivan; Rabady, Dinyar; Rahbaran, Babak; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Treberer-Treberspurg, Wolfgang; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Alderweireldt, Sara; Bansal, Monika; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Knutsson, Albert; Luyckx, Sten; Ochesanu, Silvia; Rougny, Romain; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Daci, Nadir; Heracleous, Natalie; Keaveney, James; Lowette, Steven; Maes, Michael; Olbrechts, Annik; 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Matveev, Viktor; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Skatchkov, Nikolai; Smirnov, Vitaly; Zarubin, Anatoli; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Vorobyev, Andrey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Semenov, Sergey; Spiridonov, Alexander; Stolin, Viatcheslav; Vlasov, Evgueni; Zhokin, Alexander; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Leonidov, Andrey; Mesyats, Gennady; Rusakov, Sergey V; Vinogradov, Alexey; Belyaev, Andrey; Boos, Edouard; Dubinin, Mikhail; Dudko, Lev; Ershov, Alexander; Gribushin, Andrey; Klyukhin, Vyacheslav; Kodolova, Olga; Lokhtin, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Krychkine, Victor; Petrov, Vladimir; Ryutin, Roman; Sobol, Andrei; Tourtchanovitch, Leonid; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Adzic, Petar; Ekmedzic, Marko; Milosevic, Jovan; Rekovic, Vladimir; Alcaraz Maestre, Juan; Battilana, Carlo; Calvo, Enrique; Cerrada, Marcos; Chamizo Llatas, Maria; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Domínguez Vázquez, Daniel; Escalante Del Valle, Alberto; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Garcia-Abia, Pablo; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Navarro De Martino, Eduardo; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Quintario Olmeda, Adrián; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Albajar, Carmen; de Trocóniz, Jorge F; Missiroli, Marino; Moran, Dermot; Brun, Hugues; Cuevas, Javier; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; Brochero Cifuentes, Javier Andres; Cabrillo, Iban Jose; Calderon, Alicia; Duarte Campderros, Jordi; Fernandez, Marcos; Gomez, Gervasio; Graziano, Alberto; Lopez Virto, Amparo; Marco, Jesus; Marco, Rafael; Martinez Rivero, Celso; Matorras, Francisco; Munoz Sanchez, Francisca Javiela; Piedra Gomez, Jonatan; Rodrigo, Teresa; Rodríguez-Marrero, Ana Yaiza; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Auffray, Etiennette; Auzinger, Georg; Bachtis, Michail; Baillon, Paul; Ball, Austin; Barney, David; Benaglia, Andrea; Bendavid, Joshua; Benhabib, Lamia; Benitez, Jose F; Bernet, Colin; Bloch, Philippe; Bocci, Andrea; Bonato, Alessio; Bondu, Olivier; Botta, Cristina; Breuker, Horst; Camporesi, Tiziano; Cerminara, Gianluca; Colafranceschi, Stefano; D'Alfonso, Mariarosaria; D'Enterria, David; Dabrowski, Anne; David Tinoco Mendes, Andre; De Guio, Federico; De Roeck, Albert; De Visscher, Simon; Di Marco, Emanuele; Dobson, Marc; Dordevic, Milos; Dupont-Sagorin, Niels; Elliott-Peisert, Anna; Eugster, Jürg; Franzoni, Giovanni; Funk, Wolfgang; Gigi, Dominique; Gill, Karl; Giordano, Domenico; Girone, Maria; Glege, Frank; Guida, Roberto; Gundacker, Stefan; Guthoff, Moritz; Hammer, Josef; Hansen, Magnus; Harris, Philip; Hegeman, Jeroen; Innocente, Vincenzo; Janot, Patrick; Kousouris, Konstantinos; Krajczar, Krisztian; Lecoq, Paul; Lourenco, Carlos; Magini, Nicolo; Malgeri, Luca; Mannelli, Marcello; Marrouche, Jad; Masetti, Lorenzo; Meijers, Frans; Mersi, Stefano; Meschi, Emilio; Moortgat, Filip; Morovic, Srecko; Mulders, Martijn; Musella, Pasquale; Orsini, Luciano; Pape, Luc; Perez, Emmanuelle; Perrozzi, Luca; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Pimiä, Martti; Piparo, Danilo; Plagge, Michael; Racz, Attila; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Sharma, Archana; Siegrist, Patrice; Silva, Pedro; Simon, Michal; Sphicas, Paraskevas; Spiga, Daniele; Steggemann, Jan; Stieger, Benjamin; Stoye, Markus; Takahashi, Yuta; Treille, Daniel; Tsirou, Andromachi; Veres, Gabor Istvan; Wardle, Nicholas; Wöhri, Hermine Katharina; Wollny, Heiner; Zeuner, Wolfram Dietrich; Bertl, Willi; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Renker, Dieter; Rohe, Tilman; Bachmair, Felix; Bäni, Lukas; Bianchini, Lorenzo; Buchmann, Marco-Andrea; Casal, Bruno; Chanon, Nicolas; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Dünser, Marc; Eller, Philipp; Grab, Christoph; Hits, Dmitry; Hoss, Jan; Lustermann, Werner; Mangano, Boris; Marini, Andrea Carlo; Martinez Ruiz del Arbol, Pablo; Masciovecchio, Mario; Meister, Daniel; Mohr, Niklas; Nägeli, Christoph; Nessi-Tedaldi, Francesca; Pandolfi, Francesco; Pauss, Felicitas; Peruzzi, Marco; Quittnat, Milena; Rebane, Liis; Rossini, Marco; Starodumov, Andrei; Takahashi, Maiko; Theofilatos, Konstantinos; Wallny, Rainer; Weber, Hannsjoerg Artur; Amsler, Claude; Canelli, Maria Florencia; Chiochia, Vincenzo; De Cosa, Annapaola; Hinzmann, Andreas; Hreus, Tomas; Kilminster, Benjamin; Lange, Clemens; Millan Mejias, Barbara; Ngadiuba, Jennifer; Robmann, Peter; Ronga, Frederic Jean; Taroni, Silvia; Verzetti, Mauro; Yang, Yong; Cardaci, Marco; Chen, Kuan-Hsin; Ferro, Cristina; Kuo, Chia-Ming; Lin, Willis; Lu, Yun-Ju; Volpe, Roberta; Yu, Shin-Shan; Chang, Paoti; Chang, You-Hao; Chang, Yu-Wei; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Dietz, Charles; Grundler, Ulysses; Hou, George Wei-Shu; Kao, Kai-Yi; Lei, Yeong-Jyi; Liu, Yueh-Feng; Lu, Rong-Shyang; Majumder, Devdatta; Petrakou, Eleni; Tzeng, Yeng-Ming; Wilken, Rachel; Asavapibhop, Burin; Singh, Gurpreet; Srimanobhas, Norraphat; Suwonjandee, Narumon; Adiguzel, Aytul; Bakirci, Mustafa Numan; Cerci, Salim; Dozen, Candan; Dumanoglu, Isa; Eskut, Eda; Girgis, Semiray; Gokbulut, Gul; Gurpinar, Emine; Hos, Ilknur; Kangal, Evrim Ersin; Kayis Topaksu, Aysel; Onengut, Gulsen; Ozdemir, Kadri; Ozturk, Sertac; Polatoz, Ayse; Sunar Cerci, Deniz; Tali, Bayram; Topakli, Huseyin; Vergili, Mehmet; Akin, Ilina Vasileva; Bilin, Bugra; Bilmis, Selcuk; Gamsizkan, Halil; Karapinar, Guler; Ocalan, Kadir; Sekmen, Sezen; Surat, Ugur Emrah; Yalvac, Metin; Zeyrek, Mehmet; Albayrak, Elif Asli; Gülmez, Erhan; Isildak, Bora; Kaya, Mithat; Kaya, Ozlem; Yetkin, Taylan; Cankocak, Kerem; Vardarli, Fuat Ilkehan; Levchuk, Leonid; Sorokin, Pavel; Brooke, James John; Clement, Emyr; Cussans, David; Flacher, Henning; Goldstein, Joel; Grimes, Mark; Heath, Greg P; Heath, Helen F; Jacob, Jeson; Kreczko, Lukasz; Lucas, Chris; Meng, Zhaoxia; Newbold, Dave M; Paramesvaran, Sudarshan; Poll, Anthony; Senkin, Sergey; Smith, Vincent J; Williams, Thomas; Bell, Ken W; Belyaev, Alexander; Brew, Christopher; Brown, Robert M; Cockerill, David JA; Coughlan, John A; Harder, Kristian; Harper, Sam; Olaiya, Emmanuel; Petyt, David; Shepherd-Themistocleous, Claire; Thea, Alessandro; Tomalin, Ian R; Womersley, William John; Worm, Steven; Baber, Mark; Bainbridge, Robert; Buchmuller, Oliver; Burton, Darren; Colling, David; Cripps, Nicholas; Cutajar, Michael; Dauncey, Paul; Davies, Gavin; Della Negra, Michel; Dunne, Patrick; Ferguson, William; Fulcher, Jonathan; Futyan, David; Gilbert, Andrew; Hall, Geoffrey; Iles, Gregory; Jarvis, Martyn; Karapostoli, Georgia; Kenzie, Matthew; Lane, Rebecca; Lucas, Robyn; Lyons, Louis; Magnan, Anne-Marie; Malik, Sarah; Mathias, Bryn; Nash, Jordan; Nikitenko, Alexander; Pela, Joao; Pesaresi, Mark; Petridis, Konstantinos; Raymond, David Mark; Rogerson, Samuel; Rose, Andrew; Seez, Christopher; Sharp, Peter; Tapper, Alexander; Vazquez Acosta, Monica; Virdee, Tejinder; Zenz, Seth Conrad; Cole, Joanne; Hobson, Peter R; Khan, Akram; Kyberd, Paul; Leggat, Duncan; Leslie, Dawn; Martin, William; Reid, Ivan; Symonds, Philip; 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Smith, John; Squires, Michael; Stolp, Dustin; Tripathi, Mani; Wilbur, Scott; Yohay, Rachel; Cousins, Robert; Everaerts, Pieter; Farrell, Chris; Hauser, Jay; Ignatenko, Mikhail; Rakness, Gregory; Takasugi, Eric; Valuev, Vyacheslav; Weber, Matthias; Burt, Kira; Clare, Robert; Ellison, John Anthony; Gary, J William; Hanson, Gail; Heilman, Jesse; Ivova Rikova, Mirena; Jandir, Pawandeep; Kennedy, Elizabeth; Lacroix, Florent; Long, Owen Rosser; Luthra, Arun; Malberti, Martina; Olmedo Negrete, Manuel; Shrinivas, Amithabh; Sumowidagdo, Suharyo; Wimpenny, Stephen; Branson, James G; Cerati, Giuseppe Benedetto; Cittolin, Sergio; D'Agnolo, Raffaele Tito; Holzner, André; Kelley, Ryan; Klein, Daniel; Letts, James; Macneill, Ian; Olivito, Dominick; Padhi, Sanjay; Palmer, Christopher; Pieri, Marco; Sani, Matteo; Sharma, Vivek; Simon, Sean; Sudano, Elizabeth; Tadel, Matevz; Tu, Yanjun; Vartak, Adish; Welke, Charles; Würthwein, Frank; Yagil, Avraham; Barge, Derek; Bradmiller-Feld, John; Campagnari, Claudio; Danielson, Thomas; Dishaw, Adam; Dutta, Valentina; Flowers, Kristen; Franco Sevilla, Manuel; Geffert, Paul; George, Christopher; Golf, Frank; Gouskos, Loukas; Incandela, Joe; Justus, Christopher; Mccoll, Nickolas; Richman, Jeffrey; Stuart, David; To, Wing; West, Christopher; Yoo, Jaehyeok; Apresyan, Artur; Bornheim, Adolf; Bunn, Julian; Chen, Yi; Duarte, Javier; Mott, Alexander; Newman, Harvey B; Pena, Cristian; Rogan, Christopher; Spiropulu, Maria; Timciuc, Vladlen; Vlimant, Jean-Roch; Wilkinson, Richard; Xie, Si; Zhu, Ren-Yuan; Azzolini, Virginia; Calamba, Aristotle; Carlson, Benjamin; Ferguson, Thomas; Iiyama, Yutaro; Paulini, Manfred; Russ, James; Vogel, Helmut; Vorobiev, Igor; Cumalat, John Perry; Ford, William T; Gaz, Alessandro; Krohn, Michael; Luiggi Lopez, Eduardo; Nauenberg, Uriel; Smith, James; Stenson, Kevin; Ulmer, Keith; Wagner, Stephen Robert; Alexander, James; Chatterjee, Avishek; Chaves, Jorge; Chu, Jennifer; Dittmer, Susan; Eggert, Nicholas; Mirman, Nathan; Nicolas Kaufman, Gala; 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Bochenek, Joseph; Diamond, Brendan; Haas, Jeff; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Prosper, Harrison; Veeraraghavan, Venkatesh; Weinberg, Marc; Baarmand, Marc M; Hohlmann, Marcus; Kalakhety, Himali; Yumiceva, Francisco; Adams, Mark Raymond; Apanasevich, Leonard; Bazterra, Victor Eduardo; Berry, Douglas; Betts, Russell Richard; Bucinskaite, Inga; Cavanaugh, Richard; Evdokimov, Olga; Gauthier, Lucie; Gerber, Cecilia Elena; Hofman, David Jonathan; Khalatyan, Samvel; Kurt, Pelin; Moon, Dong Ho; O'Brien, Christine; Silkworth, Christopher; Turner, Paul; Varelas, Nikos; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Duru, Firdevs; Haytmyradov, Maksat; Merlo, Jean-Pierre; Mermerkaya, Hamit; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Rahmat, Rahmat; Sen, Sercan; Tan, Ping; Tiras, Emrah; Wetzel, James; Yi, Kai; Barnett, Bruce Arnold; Blumenfeld, Barry; Bolognesi, Sara; Fehling, David; Gritsan, Andrei; Maksimovic, Petar; Martin, Christopher; Swartz, Morris; Baringer, Philip; Bean, Alice; Benelli, Gabriele; Bruner, Christopher; Kenny III, Raymond Patrick; Malek, Magdalena; Murray, Michael; Noonan, Daniel; Sanders, Stephen; Sekaric, Jadranka; Stringer, Robert; Wang, Quan; Wood, Jeffrey Scott; Chakaberia, Irakli; Ivanov, Andrew; Khalil, Sadia; Makouski, Mikhail; Maravin, Yurii; Saini, Lovedeep Kaur; Shrestha, Shruti; Skhirtladze, Nikoloz; Svintradze, Irakli; Gronberg, Jeffrey; Lange, David; Rebassoo, Finn; Wright, Douglas; Baden, Drew; Belloni, Alberto; Calvert, Brian; Eno, Sarah Catherine; Gomez, Jaime; Hadley, Nicholas John; Kellogg, Richard G; Kolberg, Ted; Lu, Ying; Marionneau, Matthieu; Mignerey, Alice; Pedro, Kevin; Skuja, Andris; Tonjes, Marguerite; Tonwar, Suresh C; Apyan, Aram; Barbieri, Richard; Bauer, Gerry; Busza, Wit; Cali, Ivan Amos; Chan, Matthew; Di Matteo, Leonardo; Gomez Ceballos, Guillelmo; Goncharov, Maxim; Gulhan, Doga; Klute, Markus; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew; Luckey, Paul David; 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Tully, Christopher; Werner, Jeremy Scott; Zuranski, Andrzej; Brownson, Eric; Mendez, Hector; Ramirez Vargas, Juan Eduardo; Barnes, Virgil E; Benedetti, Daniele; Bortoletto, Daniela; De Mattia, Marco; Gutay, Laszlo; Hu, Zhen; Jha, Manoj; Jones, Matthew; Jung, Kurt; Kress, Matthew; Leonardo, Nuno; Lopes Pegna, David; Maroussov, Vassili; Miller, David Harry; Neumeister, Norbert; Radburn-Smith, Benjamin Charles; Shi, Xin; Shipsey, Ian; Silvers, David; Svyatkovskiy, Alexey; Wang, Fuqiang; Xie, Wei; Xu, Lingshan; Yoo, Hwi Dong; Zablocki, Jakub; Zheng, Yu; Parashar, Neeti; Stupak, John; Adair, Antony; Akgun, Bora; Ecklund, Karl Matthew; Geurts, Frank JM; Li, Wei; Michlin, Benjamin; Padley, Brian Paul; Redjimi, Radia; Roberts, Jay; Zabel, James; Betchart, Burton; Bodek, Arie; Covarelli, Roberto; de Barbaro, Pawel; Demina, Regina; Eshaq, Yossof; Ferbel, Thomas; Garcia-Bellido, Aran; Goldenzweig, Pablo; Han, Jiyeon; Harel, Amnon; Khukhunaishvili, Aleko; Petrillo, Gianluca; Vishnevskiy, Dmitry; Ciesielski, Robert; Demortier, Luc; Goulianos, Konstantin; Lungu, Gheorghe; Mesropian, Christina; Arora, Sanjay; Barker, Anthony; Chou, John Paul; Contreras-Campana, Christian; Contreras-Campana, Emmanuel; Duggan, Daniel; Ferencek, Dinko; Gershtein, Yuri; Gray, Richard; Halkiadakis, Eva; Hidas, Dean; Kaplan, Steven; Lath, Amitabh; Panwalkar, Shruti; Park, Michael; Patel, Rishi; Salur, Sevil; Schnetzer, Steve; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Rose, Keith; Spanier, Stefan; York, Andrew; Bouhali, Othmane; Castaneda Hernandez, Alfredo; Eusebi, Ricardo; Flanagan, Will; Gilmore, Jason; Kamon, Teruki; Khotilovich, Vadim; Krutelyov, Vyacheslav; Montalvo, Roy; Osipenkov, Ilya; Pakhotin, Yuriy; Perloff, Alexx; Roe, Jeffrey; Rose, Anthony; Safonov, Alexei; Sakuma, Tai; Suarez, Indara; Tatarinov, Aysen; Akchurin, Nural; Cowden, Christopher; Damgov, Jordan; Dragoiu, Cosmin; Dudero, Phillip Russell; Faulkner, James; Kovitanggoon, Kittikul; Kunori, Shuichi; Lee, Sung Won; Libeiro, Terence; Volobouev, Igor; Appelt, Eric; Delannoy, Andrés G; Greene, Senta; Gurrola, Alfredo; Johns, Willard; Maguire, Charles; Mao, Yaxian; Melo, Andrew; Sharma, Monika; Sheldon, Paul; Snook, Benjamin; Tuo, Shengquan; Velkovska, Julia; Arenton, Michael Wayne; Boutle, Sarah; Cox, Bradley; Francis, Brian; Goodell, Joseph; Hirosky, Robert; Ledovskoy, Alexander; Li, Hengne; Lin, Chuanzhe; Neu, Christopher; Wood, John; Clarke, Christopher; Harr, Robert; Karchin, Paul Edmund; Kottachchi Kankanamge Don, Chamath; Lamichhane, Pramod; Sturdy, Jared; Belknap, Donald; Carlsmith, Duncan; Cepeda, Maria; Dasu, Sridhara; Dodd, Laura; Duric, Senka; Friis, Evan; Hall-Wilton, Richard; Herndon, Matthew; Hervé, Alain; Klabbers, Pamela; Lanaro, Armando; Lazaridis, Christos; Levine, Aaron; Loveless, Richard; Mohapatra, Ajit; Ojalvo, Isabel; Perry, Thomas; Pierro, Giuseppe Antonio; Polese, Giovanni; Ross, Ian; Sarangi, Tapas; Savin, Alexander; Smith, Wesley H; Taylor, Devin; Verwilligen, Piet; Vuosalo, Carl; Woods, Nathaniel

    2015-06-26

    The inclusive jet cross section for proton-proton collisions at a centre-of-mass energy of 7$~\\mathrm{TeV}$ was measured by the CMS Collaboration at the LHC with data corresponding to an integrated luminosity of 5.0$~\\mathrm{fb}^{-1}$. The measurement covers a phase space up to 2$~\\mathrm{TeV}$ in jet transverse momentum and 2.5 in absolute jet rapidity. The statistical precision of these data leads to stringent constraints on the parton distribution functions of the proton. The data provide important input for the gluon density at high fractions of the proton momentum and for the strong coupling constant at large energy scales. Using predictions from perturbative quantum chromodynamics at next-to-leading order, complemented with electroweak corrections, the constraining power of these data is investigated and the strong coupling constant at the Z boson mass $M_{\\mathrm{Z}}$ is determined to be $\\alpha_S(M_{\\mathrm{Z}}) = 0.1185 \\pm 0.0019\\,(\\mathrm{exp})\\,^{+0.0060}_{-0.0037}\\,(\\mathrm{theo})$, which is in a...

  20. W and Z production measured using the ATLAS detector, and impact on parton densities of the proton

    CERN Document Server

    Ellinghaus, F; The ATLAS collaboration

    2011-01-01

    Measurements of W and Z production cross sections in proton proton collisions are sensitive to parton distribution functions. The present status of the cross section measurements in the electron and muon decay channels is presented. The results are based on the full data set taken with the ATLAS detector in 2010. They are compared to theoretical calculations using different sets of parton distribution functions.

  1. Angular Momentum Distribution in the Transverse Plane

    CERN Document Server

    Adhikari, Lekha

    2016-01-01

    Several possibilities to relate the $t$-dependence of Generalized Parton Distributions (GPDs) to the distribution of angular momentum in the transverse plane are discussed. Using a simple spectator model we demonstrate that non of them correctly describes the orbital angular momentum distribution that for a longitudinally polarized nucleon obtained directly from light-front wavefunctions.

  2. Correlations in multi-parton interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kasemets, Tomas

    2012-07-27

    In double parton interactions, the two hard proceses are correlated via double parton densities. We examine the double Drell-Yan process and the impact of such correlations on the differential cross section. In particular correlations between the spins of the interacting quarks can induce correlations between the decay planes of the vector bosons. We investigate upper limits on spin correlations following from positivity of the double parton densities.

  3. Partonic structure of proton in the resonance region

    CERN Document Server

    Ruan, Jianhong; Chen, Xurong; Zhu, Wei

    2016-01-01

    We separate the contributions of parton distributions from higher twist corrections to the deeply inelastic lepton-proton scattering in the resonance region using the Jefferson Lab data at low $Q^2$. The study indicates that the concept of the valence quarks and their distributions are indispensable even at $Q^2<1GeV^2$. The quark-hadron duality is also discussed.

  4. Multi-parton interactions at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Kulesza, A. [RWTH Aachen (Germany). Inst. fuer Theoretische Teilchenphysik und Kosmologie; Nagy, Z. (eds.) [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-11-15

    We review the recent progress in the theoretical description and experimental observation of multiple parton interactions. Subjects covered include experimental measurements of minimum bias interactions 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. (orig.)

  5. Flow in small systems from parton scatterings

    Science.gov (United States)

    Ma, Guo-Liang; Bzdak, Adam

    2016-12-01

    We show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton-parton cross-section of σ = 1.5- 3 mb, naturally explains the long-range two-particle azimuthal correlations as observed in p+Pb collisions at the LHC. The elliptic, v2, and triangular, v3, Fourier coefficients are in good agreement with the CMS data. An escape mechanism was proposed recently to explain the AMPT results. We demonstrate that parton scatterings are directly responsible for generating the azimuthal anisotropy.

  6. A NEW FAMILY OF GENERALIZED GAMMA DISTRIBUTION AND ITS APPLICATION

    Directory of Open Access Journals (Sweden)

    Satsayamon Suksaengrakcharoen

    2014-01-01

    Full Text Available The mixture distribution is defined as one of the most important ways to obtain new probability distributions in applied probability and several research areas. According to the previous reason, we have been looking for more flexible alternative to the lifetime data. Therefore, we introduced a new mixed distribution, namely the Mixture Generalized Gamma (MGG distribution, which is obtained by mixing between generalized gamma distribution and length biased generalized gamma distribution is introduced. The MGG distribution is capable of modeling bathtub-shaped hazard rate, which contains special sub-models, namely, the exponential, length biased exponential, generalized gamma, length biased gamma and length biased generalized gamma distributions. We present some useful properties of the MGG distribution such as mean, variance, skewness, kurtosis and hazard rate. Parameter estimations are also implemented using maximum likelihood method. The application of the MGG distribution is illustrated by real data set. The results demonstrate that MGG distribution can provide the fitted values more consistent and flexible framework than a number of distribution include important lifetime data; the generalized gamma, length biased generalized gamma and the three parameters Weibull distributions.

  7. Identification of Parton Pairs in a Dijet Event and Investigation of Its Effects on Dijet Resonance Search

    Directory of Open Access Journals (Sweden)

    Sertac Ozturk

    2014-01-01

    Full Text Available Being able to distinguish parton pair type in a dijet event could significantly improve the search for new particles that are predicted by the theories beyond the Standard Model at the Large Hadron Collider. To explore whether parton pair types manifesting themselves as a dijet event could be distinguished on an event-by-event basis, I performed a simulation based study considering observable jet variables. I found that using a multivariate approach can filter out about 80% of the other parton pairs while keeping more than half of the quark-quark or gluon-gluon parton pairs in an inclusive QCD dijet distribution. The effects of event-by-event parton pair tagging for dijet resonance searches were also investigated and I found that improvement on signal significance after applying parton pair tagging can reach up to 4 times for gluon-gluon resonances.

  8. Project management under uncertainty beyond beta: The generalized bicubic distribution

    Directory of Open Access Journals (Sweden)

    José García Pérez

    2016-01-01

    Full Text Available The beta distribution has traditionally been employed in the PERT methodology and generally used for modeling bounded continuous random variables based on expert’s judgment. The impossibility of estimating four parameters from the three values provided by the expert when the beta distribution is assumed to be the underlying distribution has been widely debated. This paper presents the generalized bicubic distribution as a good alternative to the beta distribution since, when the variance depends on the mode, the generalized bicubic distribution approximates the kurtosis of the Gaussian distribution better than the beta distribution. In addition, this distribution presents good properties in the PERT methodology in relation to moderation and conservatism criteria. Two empirical applications are presented to demonstrate the adequateness of this new distribution.

  9. Building a generalized distributed system model

    Science.gov (United States)

    Mukkamala, R.

    1992-01-01

    The key elements in the second year (1991-92) of our project are: (1) implementation of the distributed system prototype; (2) successful passing of the candidacy examination and a PhD proposal acceptance by the funded student; (3) design of storage efficient schemes for replicated distributed systems; and (4) modeling of gracefully degrading reliable computing systems. In the third year of the project (1992-93), we propose to: (1) complete the testing of the prototype; (2) enhance the functionality of the modules by enabling the experimentation with more complex protocols; (3) use the prototype to verify the theoretically predicted performance of locking protocols, etc.; and (4) work on issues related to real-time distributed systems. This should result in efficient protocols for these systems.

  10. Numerical Solution of the Evolution Equation for Orbital Angular Momentum of Partons in the Nucleon

    CERN Document Server

    Martin, O; Schäfer, A

    1999-01-01

    The evolution of orbital angular momentum distributions within the radiative parton model is studied. We use different scenarios for the helicity weighted parton distributions and consider a broad range of input distributions for orbital angular momentum. In all cases we are lead to the conclusion that the absolute value of the average angular momentum per parton peaks at relatively large $x\\approx 0.1$ for perturbatively accessible scales. Furthermore, in all scenarios considered here the average orbital angular momentum per parton is several times larger for gluons than for quarks which favours gluon initiated reactions to measure orbital angular momentum. The large gluon polarization typically obtained in NLO-fits to DIS data is primarily canceled by the gluon orbital angular momentum.

  11. Multiple Parton Interactions in ALICE

    CERN Document Server

    CERN. Geneva

    2013-01-01

    We will present in detail the measurement of the charged particle multiplicity dependence of per-trigger pair yields in azimuthal direction induced by low-energetic di-jets produced in proton-proton collisions. Using two-particle angular correlations with low transverse momentum thresholds, jet properties are measured on a statistical basis down to the lowest possible jet energies. The analysis can give information about the contribution from multiple parton interactions to particle production. Moreover, the results allow to optimize the parametrization of the jet fragmentation in phenomenological mode...

  12. Parton-Hadron-String Dynamics at relativistic collider energies

    Science.gov (United States)

    Bratkovskaya, E. L.; Cassing, W.; Konchakovski, V. P.; Linnyk, O.

    2011-04-01

    The novel Parton-Hadron-String Dynamics (PHSD) transport approach is applied to nucleus-nucleus collisions at RHIC energies with respect to differential hadronic spectra in comparison to available data. The PHSD approach is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results from the Wuppertal-Budapest group in thermodynamic equilibrium. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark-antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy-momentum conservation. Our dynamical studies for heavy-ion collisions at relativistic collider energies are compared to earlier results from the Hadron-String Dynamics (HSD) approach - incorporating no explicit dynamical partonic phase - as well as to experimental data from the STAR, PHENIX, BRAHMS and PHOBOS Collaborations for Au + Au collisions at the top RHIC energy of √{s}=200 GeV. We find a reasonable reproduction of hadron rapidity distributions and transverse mass spectra and also a fair description of the elliptic flow of charged hadrons as a function of the centrality of the reaction and the transverse momentum p. Furthermore, an approximate quark-number scaling of the elliptic flow v of hadrons is observed in the PHSD results, too.

  13. Parton-Hadron-String Dynamics at relativistic collider energies

    Energy Technology Data Exchange (ETDEWEB)

    Bratkovskaya, E.L., E-mail: Elena.Bratkovskaya@th.physik.uni-frankfurt.d [Institut fuer Theoretische Physik, JWG Universitaet Frankfurt, D-60438 Frankfurt am Main (Germany); Frankfurt Institut for Advanced Studies, Frankfurt University, D-60438 Frankfurt-am-Main (Germany); Cassing, W.; Konchakovski, V.P. [Institut fuer Theoretische Physik, Universitaet Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany); Linnyk, O. [Frankfurt Institut for Advanced Studies, Frankfurt University, D-60438 Frankfurt-am-Main (Germany)

    2011-04-15

    The novel Parton-Hadron-String Dynamics (PHSD) transport approach is applied to nucleus-nucleus collisions at RHIC energies with respect to differential hadronic spectra in comparison to available data. The PHSD approach is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results from the Wuppertal-Budapest group in thermodynamic equilibrium. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark-antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy-momentum conservation. Our dynamical studies for heavy-ion collisions at relativistic collider energies are compared to earlier results from the Hadron-String Dynamics (HSD) approach - incorporating no explicit dynamical partonic phase - as well as to experimental data from the STAR, PHENIX, BRAHMS and PHOBOS Collaborations for Au + Au collisions at the top RHIC energy of {radical}(s)=200 GeV. We find a reasonable reproduction of hadron rapidity distributions and transverse mass spectra and also a fair description of the elliptic flow of charged hadrons as a function of the centrality of the reaction and the transverse momentum p{sub T}. Furthermore, an approximate quark-number scaling of the elliptic flow v{sub 2} of hadrons is observed in the PHSD results, too.

  14. Interleaved Parton Showers and Tuning Prospects

    CERN Document Server

    Corke, Richard

    2010-01-01

    General-purpose Monte Carlo event generators have become important tools in particle physics, allowing the simulation of exclusive hadronic final states. In this article we examine the Pythia 8 generator, in particular focusing on its parton-shower algorithms. Some relevant new additions to the code are introduced, that should allow for a better description of data. We also implement and compare with 2 to 3 real-emission QCD matrix elements, to check how well the shower algorithm fills the phase space away from the soft and collinear regions. A tuning of the generator to Tevatron data is performed for two PDF sets and the impact of first new LHC data is examined.

  15. On the transverse momentum in Z-boson production in a virtually ordered parton shower

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Zoltan [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Soper, Davison E. [Oregon Univ., Eugene, OR (United States). Inst. of Theoretical Science

    2009-12-15

    Cross sections for physical processes that involve very different momentum scales in the same process will involve large logarithms of the ratio of the momentum scales when calculated in perturbation theory. One goal of calculations using parton showers is to sum these large logarithms. We ask whether this goal is achieved for the transverse momentum distribution of a Z-boson produced in hadron-hadron collisions when the shower is organized with higher virtuality parton splittings coming first, followed successively by lower virtuality parton splittings. We find that the virtuality ordered shower works well in reproducing the known QCD result. (orig.)

  16. McDonald Generalized Linear Failure Rate Distribution

    Directory of Open Access Journals (Sweden)

    Ibrahim Elbatal

    2014-10-01

    Full Text Available We introduce in this paper a new six-parameters generalized version of the generalized linear failure rate (GLFR distribution which is called McDonald Generalized Linear failure rate (McGLFR distribution. The new distribution is quite flexible and can be used effectively in modeling survival data and reliability problems. It can have a constant, decreasing, increasing, and upside down bathtub-and bathtub shaped failure rate function depending on its parameters. It includes some well-known lifetime distributions as special sub-models. Some structural properties of the new distribution are studied. Moreover we discuss maximum likelihood estimation of the unknown parameters of the new model.

  17. 26 CFR 1.643(a)-0 - Distributable net income; deduction for distributions; in general.

    Science.gov (United States)

    2010-04-01

    ... § 1.643(a)-0 Distributable net income; deduction for distributions; in general. The term distributable... character of distributions to the beneficiaries. Distributable net income means for any taxable year, the... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Distributable net income; deduction...

  18. Stable and generalized-t distributions and applications

    Science.gov (United States)

    Rathie, P. N.; Coutinho, M.; Sousa, T. R.; Rodrigues, G. S.; Carrijo, T. B.

    2012-12-01

    In this paper a generalized-t distribution is introduced and used as an alternative to the symmetric stable distribution. To do so, the χ2-divergence is presented and minimized to approximate the symmetric stable distribution, as accurately as possible, by the generalized-t distribution. Kth moments for the generalized-t distribution function are given. The stable distribution is defined in terms of generalized hypergeometric functions. Five applications with natural data (sunspots activity), and financial data (stock exchange in Brazil, South Africa and Venezuela, and daily variation of Petrobras stock market) are analyzed. A time series analysis is used to eliminate data correlation in each data set, and then the distributions are used to fit the residuals of these models.

  19. A Parton Shower for High Energy Jets

    DEFF Research Database (Denmark)

    Andersen, Jeppe Rosenkrantz; Lonnblad, Leif; M. Smillie, Jennifer

    2011-01-01

    We present a method to match the multi-parton states generated by the High Energy Jets Monte Carlo with parton showers generated by the Ariadne program using the colour dipole model. The High Energy Jets program already includes a full resummation of soft divergences. Hence, in the matching...

  20. A Parton Shower for High Energy Jets

    DEFF Research Database (Denmark)

    Andersen, Jeppe Rosenkrantz; Lonnblad, Leif; M. Smillie, Jennifer

    2011-01-01

    We present a method to match the multi-parton states generated by the High Energy Jets Monte Carlo with parton showers generated by the Ariadne program using the colour dipole model. The High Energy Jets program already includes a full resummation of soft divergences. Hence, in the matching...

  1. Jet Hadronization via Recombination of Parton Showers in Vacuum and in Medium

    Science.gov (United States)

    Fries, Rainer J.; Han, Kyongchol; Ko, Che Ming

    2016-12-01

    We introduce a hadronization algorithm for jet parton showers based on a hybrid approach involving recombination of quarks and fragmentation of strings. The algorithm can be applied to parton showers from a shower Monte Carlo generator at the end of their perturbative evolution. The algorithm forces gluon decays and then evaluates the recombination probabilities for quark-antiquark pairs into mesons and (anti)quark triplets into (anti)baryons. We employ a Wigner phase space formulation based on the assumption of harmonic oscillator wave functions for stable hadrons and resonances. Partons too isolated in phase space to find recombination partners are connected by QCD strings to other quarks. Fragmentation of those remnant strings and the decay of all hadron resonances complete the hadronization process. We find that our model applied to parton showers from the PYTHIA Monte Carlo event generator leads to results very similar to pure Lund string fragmentation. We suggest that our algorithm can be readily generalized to jets embedded in quark-gluon plasma by adding sampled thermal partons from the phase transition hypersurface. The recombination of thermal partons and shower partons leads to an enhancement of pions and protons at intermediate momentum at both RHIC and LHC.

  2. Detailed comparison between parton cascade and hadronic cascade at SPS and RHIC

    CERN Document Server

    Nara, Y; Longacre, R S

    1999-01-01

    We study the importance of the partonic phase produced in relativistic heavy ion collision by comparing the parton cascade model and the hadronic cascade model. Hadron yield, baryon stopping and transverse momentum distribution are calculated with JAM and discussions are given comparing with VNI. Both of these models give good description of experimental data. We also discuss the strangeness production mechanism and the directed transverse flow. (21 refs).

  3. THE ROC CURVE MODEL FROM GENERALIZED-EXPONENTIAL DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Ehtesham Hussain

    2011-04-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 In biomedical studies often yield continuously positively skewed (non- normal distributed data. In this regard Generalized-Exponential Distribution is suggested for analyzing such data. In this paper the parametric equation of  the Receiving Operating Characteristic (ROC curve model is established under the assumptions of bi-distributional population based on pair of Generalized-Exponential Distributions. Also its maximum likelihood estimator MLE, sampling distribution , equivalence test statistic and exact confidence interval are derived.  

  4. General results for the Marshall and Olkin's family of distributions

    Directory of Open Access Journals (Sweden)

    WAGNER BARRETO-SOUZA

    2013-03-01

    Full Text Available Abstract Marshall and Olkin (1997 introduced an interesting method of adding a parameter to a well-established distribution. However, they did not investigate general mathematical properties of their family of distributions. We provide for this family of distributions general expansions for the density function, explicit expressions for the moments and moments of the order statistics. Several especial models are investigated. We discuss estimation of the model parameters. An application to a real data set is presented for illustrative purposes.

  5. Relating transverse structure of various parton distributions

    CERN Document Server

    Maji, Tanmay; Chakrabarti, D; Teryaev, O V

    2015-01-01

    We present the results of T-even TMDs in a light front quark-diquark model of nucleons with the wave functions constructed from the soft-wall AdS/QCD prediction. The relations amongst TMDs are discussed. The $p_\\perp$ dependence of the TMDs are compared with the $t$-dependence of the GPDs. AdS/QCD wave function provides an explanation behind the approximate $x$ and $p_\\perp$ factorization observed in lattice TMD calculations.

  6. On Generalized Upper(kRecord Values From Weibull Distribution

    Directory of Open Access Journals (Sweden)

    Jerin Paul

    2015-09-01

    Full Text Available In this paper we study the generalized upper(krecord values arising from Weibull distribution. Expressions for the moments and product moments of those generalized upper(krecord values  are derived. Some properties of generalized upper(krecord values which characterize the Weibull distribution  have been established. Also some distributional properties of generalized upper(krecord values arising from Weibull distribution are considered and used for suggesting an estimator for the shape parameter of Weibull distribution. The location and scale parameters are estimated using the Best Linear Unbiased Estimation procedure. Prediction of a future record using Best Linear Unbiased Predictor has been studied. A real life data is used to illustrate the results generated in this work.

  7. Photons in a partonic transport approach

    Energy Technology Data Exchange (ETDEWEB)

    Greif, Moritz; Senzel, Florian; Greiner, Carsten [Goethe Universitaet Frankfurt, Max-von-Laue-Str. 1 60438 Frankfurt am Main (Germany)

    2015-07-01

    Partonic transport approaches have proved to be valuable tools in describing the quark-gluon plasma, created in heavy-ion collisions. In this work, first steps towards a dynamical understanding of photonproduction in expanding heavy-ion collisions are presented. Several photon production processes are included in the partonic cascade BAMPS (Boltzmann Approach to Multi-Parton Scatterings). BAMPS provides a microscopic tool to study expanding fireballs, employing a stochastic method to solve the relativistic 3+1d Boltzmann equation. Subsequently, photon spectra can be investigated, and in particular, the influence of the quark-gluon plasma phase for the elliptic flow of photons is studied.

  8. Implementing NLO DGLAP evolution in Parton Showers

    Energy Technology Data Exchange (ETDEWEB)

    Höche, Stefan [SLAC; Krauss, Frank [Durham U., IPPP; Prestel, Stefan [Fermilab

    2017-05-02

    We present a parton shower which implements the DGLAP evolution of parton densities and fragmentation functions at next-to-leading order precision up to effects stemming from local four-momentum conservation. The Monte-Carlo simulation is based on including next-to-leading order collinear splitting functions in an existing parton shower and combining their soft enhanced contributions with the corresponding terms at leading order. Soft double counting is avoided by matching to the soft eikonal. Example results from two independent realizations of the algorithm, implemented in the two event generation frameworks Pythia and Sherpa, illustrate the improved precision of the new formalism.

  9. Generalized Poisson distribution: the property of mixture of Poisson and comparison with negative binomial distribution.

    Science.gov (United States)

    Joe, Harry; Zhu, Rong

    2005-04-01

    We prove that the generalized Poisson distribution GP(theta, eta) (eta > or = 0) is a mixture of Poisson distributions; this is a new property for a distribution which is the topic of the book by Consul (1989). Because we find that the fits to count data of the generalized Poisson and negative binomial distributions are often similar, to understand their differences, we compare the probability mass functions and skewnesses of the generalized Poisson and negative binomial distributions with the first two moments fixed. They have slight differences in many situations, but their zero-inflated distributions, with masses at zero, means and variances fixed, can differ more. These probabilistic comparisons are helpful in selecting a better fitting distribution for modelling count data with long right tails. Through a real example of count data with large zero fraction, we illustrate how the generalized Poisson and negative binomial distributions as well as their zero-inflated distributions can be discriminated.

  10. The use of Generalised Functions and Distributions in General Relativity

    CERN Document Server

    Steinbauer, R; Steinbauer, Roland; Vickers, James A.

    2006-01-01

    In this paper we review the extent to which one can use classical distribution theory in describing solutions of Einstein's equations. We show that there are a number of physically interesting cases which cannot be treated using distribution theory but require a more general concept. We describe a mathematical theory of nonlinear generalised functions based on Colombeau algebras and show how this may be applied in general relativity. We end by discussing the concept of singularity in general relativity and show that certain solutions with weak singularities may be regarded as distributional solutions of Einstein's equations.

  11. Matching fully differential NNLO calculations and parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Alioli, Simone; Bauer, Christian W.; Berggren, Calvin; Walsh, Jonathan R.; Zuberi, Saba [California Univ., Berkeley, CA (United States). Ernest Orlando Lawrence Berkeley National Laboratory; Tackmann, Frank J. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-11-15

    We present a general method to match fully differential next-to-next-to-leading (NNLO) calculations to parton shower programs. We discuss in detail the perturbative accuracy criteria a complete NNLO+PS matching has to satisfy. Our method is based on consistently improving a given NNLO calculation with the leading-logarithmic (LL) resummation in a chosen jet resolution variable. The resulting NNLO+LL calculation is cast in the form of an event generator for physical events that can be directly interfaced with a parton shower routine, and we give an explicit construction of the input ''Monte Carlo cross sections'' satisfying all required criteria. We also show how other proposed approaches naturally arise as special cases in our method.

  12. Matching Fully Differential NNLO Calculations and Parton Showers

    CERN Document Server

    Alioli, Simone; Berggren, Calvin; Tackmann, Frank J; Walsh, Jonathan R; Zuberi, Saba

    2013-01-01

    We present a general method to match fully differential next-to-next-to-leading (NNLO) calculations to parton shower programs. We discuss in detail the perturbative accuracy criteria a complete NNLO+PS matching has to satisfy. Our method is based on consistently improving a given NNLO calculation with the leading-logarithmic (LL) resummation in a chosen jet resolution variable. The resulting NNLO$+$LL calculation is cast in the form of an event generator for physical events that can be directly interfaced with a parton shower routine, and we give an explicit construction of the input "Monte Carlo cross sections" satisfying all required criteria. We also show how other proposed approaches naturally arise as special cases in our method.

  13. A general algorithm for distributing information in a graph

    OpenAIRE

    Aji, Srinivas M.; McEliece, Robert J.

    1997-01-01

    We present a general “message-passing” algorithm for distributing information in a graph. This algorithm may help us to understand the approximate correctness of both the Gallager-Tanner-Wiberg algorithm, and the turbo-decoding algorithm.

  14. Extreme Risk In Resource Indices And The Generalized Logistic Distribution

    National Research Council Canada - National Science Library

    Chun-Kai Huang; Venelle Pather; Jahvaid Hammujuddy; Knowledge Chinhamu

    2017-01-01

    .... In this article, we compare performances of classical extreme value models against the recently suggested generalized logistic distribution, for estimating value-at-risk and expected shortfall in resource indices...

  15. A generalized statistical model for the size distribution of wealth

    Science.gov (United States)

    Clementi, F.; Gallegati, M.; Kaniadakis, G.

    2012-12-01

    In a recent paper in this journal (Clementi et al 2009 J. Stat. Mech. P02037), we proposed a new, physically motivated, distribution function for modeling individual incomes, having its roots in the framework of the κ-generalized statistical mechanics. The performance of the κ-generalized distribution was checked against real data on personal income for the United States in 2003. In this paper we extend our previous model so as to be able to account for the distribution of wealth. Probabilistic functions and inequality measures of this generalized model for wealth distribution are obtained in closed form. In order to check the validity of the proposed model, we analyze the US household wealth distributions from 1984 to 2009 and conclude an excellent agreement with the data that is superior to any other model already known in the literature.

  16. Picturing perturbative parton cascades in QCD matter

    Directory of Open Access Journals (Sweden)

    Aleksi Kurkela

    2015-01-01

    Full Text Available Based on parametric reasoning, we provide a simple dynamical picture of how a perturbative parton cascade, in interaction with a QCD medium, fills phase space as a function of time.

  17. Pre-equilibrium parton dynamics: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin-Nian [ed.

    1993-12-31

    This report contains papers on the following topics: parton production and evolution; QCD transport theory; interference in the medium; QCD and phase transition; and future heavy ion experiments. This papers have been indexed separately elsewhere on the data base.

  18. Studies of parton thermalization at RHIC

    CERN Document Server

    Shin, G R; Shin, Ghi R.; Müller, Berndt

    2003-01-01

    We consider the evolution of a parton system which is formed in the central region just after a relativistic heavy ion collision. The parton consist of mostly gluons, minijets, which are produced by elastic scattering between constituent partons of the colliding nuclei. We assume the system can be described by a semi-classical Boltzmann transport equation, which we solve by means of the test particle Monte-Carlo method including retardation. The partons proliferate via secondary radiative $gg \\to ggg$ processes until the thermalization is reached for some assumptions. The extended system is thermalized at about $t=1.6$ fm/$c$ with $T = 570$ MeV and stays in equilibrium for about 2 fm/$c$ with breaking temperature $T = 360$ MeV in the rapidity central region.

  19. Triple collinear emissions in parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Höche, Stefan [SLAC; Prestel, Stefan [Fermilab

    2017-05-01

    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 integration and the analytic computation of NLO DGLAP evolution kernels is made explicit for both timelike and spacelike parton evolution. Numerical simulation results are obtained with two independent implementations of the new algorithm, using the two independent event generation frameworks Pythia and Sherpa.

  20. Bayesian Analysis for Binomial Models with Generalized Beta Prior Distributions.

    Science.gov (United States)

    Chen, James J.; Novick, Melvin, R.

    1984-01-01

    The Libby-Novick class of three-parameter generalized beta distributions is shown to provide a rich class of prior distributions for the binomial model that removes some restrictions of the standard beta class. A numerical example indicates the desirability of using these wider classes of densities for binomial models. (Author/BW)

  1. Asymptotic distributions for a class of generalized $L$-statistics

    CERN Document Server

    Borovskikh, Yuri V; 10.3150/09-BEJ240

    2010-01-01

    We adapt the techniques in Stigler [Ann. Statist. 1 (1973) 472--477] to obtain a new, general asymptotic result for trimmed $U$-statistics via the generalized $L$-statistic representation introduced by Serfling [Ann. Statist. 12 (1984) 76--86]. Unlike existing results, we do not require continuity of an associated distribution at the truncation points. Our results are quite general and are expressed in terms of the quantile function associated with the distribution of the $U$-statistic summands. This approach leads to improved conditions for the asymptotic normality of these trimmed $U$-statistics.

  2. Lumped and distributed passive networks a generalized and advanced viewpoint

    CERN Document Server

    Wohlers, M Ronald; Declaris, Nicholas

    1969-01-01

    Lumped and Distributed Passive Networks: A Generalized and Advanced Viewpoint considers the mathematical study of a subset of passive linear operators. This five-chapter focuses on the questions of analysis and representation of such operators and illustrates the results of these analyses by obtaining some of the limitations that are imposed on the performance of passive systems. The first two chapters deal with the structure of general linear passive operators. These chapters specifically look into the theory of distributions, called generalized functions. The third and fourth chapters illust

  3. Generalized Cumulative Residual Entropy for Distributions with Unrestricted Supports

    Directory of Open Access Journals (Sweden)

    Noomane Drissi

    2008-01-01

    Full Text Available We consider the cumulative residual entropy (CRE a recently introduced measure of entropy. While in previous works distributions with positive support are considered, we generalize the definition of CRE to the case of distributions with general support. We show that several interesting properties of the earlier CRE remain valid and supply further properties and insight to problems such as maximum CRE power moment problems. In addition, we show that this generalized CRE can be used as an alternative to differential entropy to derive information-based optimization criteria for system identification purpose.

  4. Bayesian estimation of generalized exponential distribution under noninformative priors

    Science.gov (United States)

    Moala, Fernando Antonio; Achcar, Jorge Alberto; Tomazella, Vera Lúcia Damasceno

    2012-10-01

    The generalized exponential distribution, proposed by Gupta and Kundu (1999), is a good alternative to standard lifetime distributions as exponential, Weibull or gamma. Several authors have considered the problem of Bayesian estimation of the parameters of generalized exponential distribution, assuming independent gamma priors and other informative priors. In this paper, we consider a Bayesian analysis of the generalized exponential distribution by assuming the conventional noninformative prior distributions, as Jeffreys and reference prior, to estimate the parameters. These priors are compared with independent gamma priors for both parameters. The comparison is carried out by examining the frequentist coverage probabilities of Bayesian credible intervals. We shown that maximal data information prior implies in an improper posterior distribution for the parameters of a generalized exponential distribution. It is also shown that the choice of a parameter of interest is very important for the reference prior. The different choices lead to different reference priors in this case. Numerical inference is illustrated for the parameters by considering data set of different sizes and using MCMC (Markov Chain Monte Carlo) methods.

  5. Approximations of the Generalized Log-Logistic Distribution to the Chi-Square Distribution

    Directory of Open Access Journals (Sweden)

    Kartika Candra Buana

    2014-12-01

    Full Text Available The main purpose of this article is to do approximations graphically and mathematically the four-parameter generalized log-logistic distribution, denoted by G4LL(α,β,m_1,m_2, to the one-parameter Chi-square distribution with υ degrees of freedom. In order to achieve this purpose, this article creates graphically the probability density functions of both distribution and derives mathematically the MGF of the both distributions. To prove the MGF of Chi-square as a special case of the MGF of G4LL distribution, we utilized an expansion of the MacLaurin series. The results show that graphically, the Chi-square distribution can be approximated by the generalized log-logistic distribution. Moreover, by letting α=1,β=-ln⁡(2m_2 ,m_1=v/2 and m_2→∞, the MGF of the G4LL distribution can be written in the form of the MGF of the Chi-square distribution. Thus, the Chi-square distribution is a limiting or special case distribution of the generalized log-logistic distribution.The main purpose of this article is to do approximations graphically and mathematically the four-parameter generalized log-logistic distribution, denoted by G4LL(α,β,m_1,m_2, to the one-parameter Chi-square distribution with υ degrees of freedom. In order to achieve this purpose, this article creates graphically the probability density functions of both distribution and derives mathematically the MGF of the both distributions. To prove the MGF of Chi-square as a special case of the MGF of G4LL distribution, we utilized an expansion of the MacLaurin series. The results show that graphically, the Chi-square distribution can be approximated by the generalized log-logistic distribution. Moreover, by letting α=1,β=-ln⁡(2m_2 ,m_1=v/2 and m_2→∞, the MGF of the G4LL distribution can be written in the form of the MGF of the Chi-square distribution. Thus, the Chi-square distribution is a limiting or special case distribution of the generalized log-logistic distribution.

  6. Uncertainties of the 50-year wind from short time series using generalized extreme value distribution and generalized Pareto distribution

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Mann, Jakob; Rathmann, Ole

    2015-01-01

    as a guideline for applying GEVD and GPD to wind time series of limited length. The data analysis shows that, with reasonable choice of relevant parameters, GEVD and GPD give consistent estimates of the return winds. For GEVD, the base period should be chosen in accordance with the occurrence of the extreme wind......This study examines the various sources to the uncertainties in the application of two widely used extreme value distribution functions, the generalized extreme value distribution (GEVD) and the generalized Pareto distribution (GPD). The study is done through the analysis of measurements from...

  7. The New Kumaraswamy Kumaraswamy Family of Generalized Distributions with Application

    Directory of Open Access Journals (Sweden)

    Mohamed Ali Ahmed

    2015-08-01

    Full Text Available Finding the best fitted distribution for data set becomes practically an important problem in world of data sets so that it is useful to use new families of distributions to fit more cases or get better fits than before.  In this paper, a new generating family of generalized distributions so called the Kumaraswamy - Kumaraswamy (KW-KW family is presented. Four important common families of distributions are illustrated as special cases from the KW KW family. Moments, probability weighted moments, moment generating function, quantile function, median, mean deviation, order statistics and moments of order statistics are obtained. Parameters estimation and variance covariance matrix are computed using maximum likelihood method. A real data set is used to illustrate the potentiality of the KW KW weibull distribution (which derived from the kw kw family compared with other distributions.

  8. DbarD and DD pair production at the LHCb in the parton Reggeization approach

    CERN Document Server

    Karpishkov, A V; Saleev, V A; Shipilova, A V

    2016-01-01

    We study the inclusive DbarD and DD pair production in proton-proton collisions at the LHC at lead- ing order of the parton Reggeization approach endowed with universal scale-depended fragmen- tation functions for c-quark to D-meson and for gluon to D-meson transitions. We have described DbarD and DD distributions in azimuthal angle, as well as transverse momentum, rapidity distance, and invariant mass measured in the region of large rapidity 2 < y < 4 by the LHCb Collabora- tion at the LHC without free parameters. We have used Reggeized amplitudes for the processes RR - gg and RR - c barc which are obtained accordingly to Feynman rules of the L.N. Lipatov effective theory of Reggeized partons, and Kimber-Martin-Ryskin model for unintegrated gluon distribution function in a proton with Martin-Stirling-Thorne-Watt collinear parton distributions as inputs.

  9. VNI-3.1 MC-simulation program to study high-energy particle collisions in QCD by space-time evolution of parton-cascades and parton-hadron conversion

    CERN Document Server

    Kinder-Geiger, Klaus

    1997-01-01

    VNI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. On the basis of renormalization-group improved parton description and quantum-kinetic theory, it uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme that is governed by the dynamics itself. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time-development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position-space, momentum-space and color-space. The parton-evolution is described in terms of a space-time generalization of the familiar momentum-space description of multipl (semi) hard interactions in QCD, involving 2 -> 2 parton collisions, 2 -> 1 parton fusion processes, and 1 -> 2 radiation processes. The formation of color-singlet pre-hadronic...

  10. Stability of a Generalized Quadratic Functional Equation in Schwartz Distributions

    Institute of Scientific and Technical Information of China (English)

    Jae-Young CHUNG

    2009-01-01

    We consider the Hyers-Ulam stability problem of the generalized quadratic functional equation u(o)A+v(o)B-2w(o)P1-2k(o)P2=0, which is a distributional version of the classical generalized quadratic functional equation f(x + y) + g(x - y) - 2h(x) - 2k(y) = 0.

  11. Gyrokinetic simulations with a general equilibrium distribution function

    Science.gov (United States)

    Wilkie, George; Highcock, Edmund; Abel, Ian; Dorland, William

    2013-10-01

    Applying the gyrokinetic framework to study the dynamics of fast particles requires a transport-scale equilibrium distribution that is not Maxwellian, and whose functional form may not be known a priori. The GS2 gyrokinetics code has been modified to accommodate an arbitrary equilibrium distribution and this capability has been validated. The need to resolve the tail of the distribution for fast particles introduces numerical challenges that are resolved by implementing a generalized quadrature scheme that retains spectral accuracy of velocity-space integrals. Preliminary simulation results are presented.

  12. A generalization of the half-normal distribution

    Institute of Scientific and Technical Information of China (English)

    Yolanda M Gomez; Ignacio Vidal

    2016-01-01

    In this paper we introduce an extension of the half-normal distribution in order to model a great variety of non-negative data. Its hazard rate function can be decreasing or increasing, depending on its parameters. Some properties of this new distribution are presented. For example, we give a general expression for the moments and a stochastic representation. Also, the cumulative distribution function, the hazard rate function, the survival function and the quantile function can be easily evaluated. Maximum likelihood estimators can be computed by using numerical procedures. Finally, a real-life dataset has been presented to illustrate its applicability.

  13. Influence of Generalized (r, q) Distribution Function on Electrostatic Waves

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping ofelectron plasma (Langmuir) waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized (r, q) distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.

  14. A generalization of the power law distribution with nonlinear exponent

    Science.gov (United States)

    Prieto, Faustino; Sarabia, José María

    2017-01-01

    The power law distribution is usually used to fit data in the upper tail of the distribution. However, commonly it is not valid to model data in all the range. In this paper, we present a new family of distributions, the so-called Generalized Power Law (GPL), which can be useful for modeling data in all the range and possess power law tails. To do that, we model the exponent of the power law using a non-linear function which depends on data and two parameters. Then, we provide some basic properties and some specific models of that new family of distributions. After that, we study a relevant model of the family, with special emphasis on the quantile and hazard functions, and the corresponding estimation and testing methods. Finally, as an empirical evidence, we study how the debt is distributed across municipalities in Spain. We check that power law model is only valid in the upper tail; we show analytically and graphically the competence of the new model with municipal debt data in the whole range; and we compare the new distribution with other well-known distributions including the Lognormal, the Generalized Pareto, the Fisk, the Burr type XII and the Dagum models.

  15. Intrinsic charm in a matched general-mass scheme

    Directory of Open Access Journals (Sweden)

    Richard D. Ball

    2016-03-01

    Full Text Available The FONLL general-mass variable-flavour number scheme provides a framework for the matching of a calculation in which a heavy quark is treated as a massless parton to one in which the mass dependence is retained throughout. We describe how the usual formulation of FONLL can be extended in such a way that the heavy quark parton distribution functions are freely parameterized at some initial scale, rather than being generated entirely perturbatively. We specifically consider the case of deep-inelastic scattering, in view of applications to PDF determination, and the possible impact of a fitted charm quark distribution on F2c is assessed.

  16. Search for optimal conditions for exploring double-parton scattering in four-jet production: $k_t$-factorization approach

    CERN Document Server

    Kutak, Krzysztof; Serino, Mirko; Szczurek, Antoni; van Hameren, Andreas

    2016-01-01

    In the present paper we discuss how to maximize the double-parton scattering (DPS) contribution in four-jet production. Here both single-parton and double-parton scattering effects are calculated in the $k_t$-factorization approach, following our recent developments of relevant methods and tools. Several differential distributions are shown and discussed in the context of future searches for DPS effects, such as rapidity of jets, rapidity distance, and azimuthal correlations between jets. The dependences of the relative DPS amount is studied as function of those observables. The regions with an enhanced DPS contribution are identified. Future experimental explorations could extract more precise values of $\\sigma_{eff}$.

  17. A generalized Dirichlet distribution accounting for singularities of the variables

    DEFF Research Database (Denmark)

    Lewy, Peter

    1996-01-01

    A multivariate generalized Dirichlet distribution has been formulated for the case where the stochastic variables are allowed to have singularities at 0 and 1. Small sample properties of the estimates of moments of the variables based on maximum likelihood estimates of the parameters have been co...

  18. Distributed Systems of Generalizing as the Basis of Workplace Learning

    Science.gov (United States)

    Virkkunen, Jaakko; Pihlaja, Juha

    2004-01-01

    This article proposes a new way of conceptualizing workplace learning as distributed systems of appropriation, development and the use of practice-relevant generalizations fixed within mediational artifacts. This article maintains that these systems change historically as technology and increasingly sophisticated forms of production develop.…

  19. A Comparison of new MC-adapted Parton Densities

    CERN Document Server

    Kasemets, Tomas

    2010-01-01

    A selection of the latest and most frequently used parton distribution functions (PDFs) is incorporated in Pythia8, including the Monte Carlo-adapted PDFs from the MSTW and CTEQ collaborations. This article examines the differences in PDFs as well as the effect they have on results of simulations and compare with data collected by the CDF experiment. Monte Carlo-adapted PDFs do a better job than leading- and next-to-leading order PDFs for many observables, but there is room for further improvements.

  20. APFELgrid: a high performance tool for parton density determinations

    CERN Document Server

    Bertone, Valerio; Hartland, Nathan P

    2016-01-01

    We present a new software package designed to reduce the computational burden of hadron collider measurements in Parton Distribution Function (PDF) fits. The APFELgrid package converts interpolated weight tables provided by APPLgrid files into a more efficient format for PDF fitting by the combination with PDF and $\\alpha_s$ evolution factors provided by APFEL. This combination significantly reduces the number of operations required to perform the calculation of hadronic observables in PDF fits and simplifies the structure of the calculation into a readily optimised scalar product. We demonstrate that our technique can lead to a substantial speed improvement when compared to existing methods without any reduction in numerical accuracy.

  1. APFELgrid : A high performance tool for parton density determinations

    Science.gov (United States)

    Bertone, Valerio; Carrazza, Stefano; Hartland, Nathan P.

    2017-03-01

    We present a new software package designed to reduce the computational burden of hadron collider measurements in Parton Distribution Function (PDF) fits. The APFELgrid package converts interpolated weight tables provided by APPLgrid files into a more efficient format for PDF fitting by the combination with PDF and αs evolution factors provided by APFEL. This combination significantly reduces the number of operations required to perform the calculation of hadronic observables in PDF fits and simplifies the structure of the calculation into a readily optimised scalar product. We demonstrate that our technique can lead to a substantial speed improvement when compared to existing methods without any reduction in numerical accuracy.

  2. Three-Parton Contributions to B --> M_1 M_2 Annihilation at Leading Order

    CERN Document Server

    Arnesen, C M; Stewart, I W; Arnesen, Christian M.; Rothstein, Ira Z.; Stewart, Iain W.

    2006-01-01

    We compute annihilation amplitudes for charmless B decays that are proportional to the three-parton twist-3 light meson distribution amplitude phi_{3M}(x1,x2) with an active gluon. Due to an enhancement from a quark propagator at the scale p^2 ~ mb\\Lambda_QCD these terms occur at the same parametric order in alpha_s(mb) and 1/mb as the known leading order annihilation involving fB and twist-2 meson distributions. With our calculation the leading order annihilation amplitude is now complete. At lowest order in alpha_s the amplitudes are real and only O_{5-8} contribute. Using simple models we find that the three-parton and two-parton terms are of comparable size.

  3. Electroweakino pair production at the LHC: NLO SUSY-QCD corrections and parton-shower effects

    CERN Document Server

    Baglio, Julien; Kesenheimer, Matthias

    2016-01-01

    We present a set of NLO SUSY-QCD calculations for the pair production of neutralinos and charginos at the LHC, and their matching to parton-shower programs in the framework of the POWHEG-BOX program package. The code we have developed provides a SUSY Les Houches Accord interface for setting supersymmetric input parameters. Decays of the neutralinos and charginos and parton-shower effects can be simulated with PYTHIA. To illustrate the capabilities of our program, we present phenomenological results for a representative SUSY parameter point. We find that NLO-QCD corrections increase the production rates for neutralinos and charginos significantly. The impact of parton-shower effects on distributions of the weakinos is small, but non-negligible for jet distributions.

  4. Measurement of parton shower observables with OPAL

    Science.gov (United States)

    Fischer, N.; Gieseke, S.; Kluth, S.; Plätzer, S.; Skands, P.

    2016-07-01

    A study of QCD coherence is presented based on a sample of about 397,000 e+e- hadronic annihilation events collected at √s = 91 GeV with the OPAL detector at LEP. The study is based on four recently proposed observables that are sensitive to coherence effects in the perturbative regime. The measurement of these observables is presented, along with a comparison with the predictions of different parton shower models. The models include both conventional parton shower models and dipole antenna models. Different ordering variables are used to investigate their influence on the predictions.

  5. Measurement of parton shower observables with OPAL

    Directory of Open Access Journals (Sweden)

    Fischer N.

    2016-01-01

    Full Text Available A study of QCD coherence is presented based on a sample of about 397,000 e+e- hadronic annihilation events collected at √s = 91 GeV with the OPAL detector at LEP. The study is based on four recently proposed observables that are sensitive to coherence effects in the perturbative regime. The measurement of these observables is presented, along with a comparison with the predictions of different parton shower models. The models include both conventional parton shower models and dipole antenna models. Different ordering variables are used to investigate their influence on the predictions.

  6. Parton-to-Pion Fragmentation Reloaded

    CERN Document Server

    de Florian, D; Epele, M; Hernandez-Pinto, R J; Stratmann, M

    2014-01-01

    We present a new, comprehensive global analysis of parton-to-pion fragmentation functions at next-to-leading order accuracy in QCD. The obtained results are based on the latest experimental information on single-inclusive pion production in electron-positron annihilation, lepton-nucleon deep-inelastic scattering, and proton-proton collisions. An excellent description of all data sets is achieved, and the remaining uncertainties in parton-to-pion fragmentation functions are estimated based on the Hessian method. Extensive comparisons to the results from our previous global analysis are performed.

  7. Parton Propagation and Fragmentation in QCD Matter

    Energy Technology Data Exchange (ETDEWEB)

    Alberto Accardi, Francois Arleo, William Brooks, David D' Enterria, Valeria Muccifora

    2009-12-01

    We review recent progress in the study of parton propagation, interaction and fragmentation in both cold and hot strongly interacting matter. Experimental highlights on high-energy hadron production in deep inelastic lepton-nucleus scattering, proton-nucleus and heavy-ion collisions, as well as Drell-Yan processes in hadron-nucleus collisions are presented. The existing theoretical frameworks for describing the in-medium interaction of energetic partons and the space-time evolution of their fragmentation into hadrons are discussed and confronted to experimental data. We conclude with a list of theoretical and experimental open issues, and a brief description of future relevant experiments and facilities.

  8. Stress-strength reliability for general bivariate distributions

    Directory of Open Access Journals (Sweden)

    Alaa H. Abdel-Hamid

    2016-10-01

    Full Text Available An expression for the stress-strength reliability R=P(X1general bivariate distribution. Such distribution includes bivariate compound Weibull, bivariate compound Gompertz, bivariate compound Pareto, among others. In the parametric case, the maximum likelihood estimates of the parameters and reliability function R are obtained. In the non-parametric case, point and interval estimates of R are developed using Govindarajulu's asymptotic distribution-free method when X1 and X2 are dependent. An example is given when the population distribution is bivariate compound Weibull. Simulation is performed, based on different sample sizes to study the performance of estimates.

  9. Inversion of generalized relaxation time distributions with optimized damping parameter

    Science.gov (United States)

    Florsch, Nicolas; Revil, André; Camerlynck, Christian

    2014-10-01

    Retrieving the Relaxation Time Distribution (RDT), the Grains Size Distribution (GSD) or the Pore Size Distribution (PSD) from low-frequency impedance spectra is a major goal in geophysics. The “Generalized RTD” generalizes parametric models like Cole-Cole and many others, but remains tricky to invert since this inverse problem is ill-posed. We propose to use generalized relaxation basis function (for instance by decomposing the spectra on basis of generalized Cole-Cole relaxation elements instead of the classical Debye basis) and to use the L-curve approach to optimize the damping parameter required to get smooth and realistic inverse solutions. We apply our algorithm to three examples, one synthetic and two real data sets, and the program includes the possibility of converting the RTD into GSD or PSD by choosing the value of the constant connecting the relaxation time to the characteristic polarization size of interest. A high frequencies (typically above 1 kHz), a dielectric term in taken into account in the model. The code is provided as an open Matlab source as a supplementary file associated with this paper.

  10. A New Effect in the QCD Fusion of Nuclear Partons

    Institute of Scientific and Technical Information of China (English)

    RUAN Jian-Hong; ZHU Wei; LI Guang-Lie

    2001-01-01

    The parton fusion in nucleus at the leading order of recombination is investigated based on perturbative QCD. We compute various cut diagrams including the nuclear parton fusion, and find that the parton-fusion effects depend on the nuclear QCD structure.``

  11. Systematic Improvement of QCD Parton Showers

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Jan; /CERN; Hoeche, Stefan; /SLAC; Hoeth, Hendrik; Krauss, Frank; Schonherr, Marek; Zapp, Korinna; /Durham U., IPPP; Schumann, Steffen; /Gottingen U., II. Phys. Inst.; Siegert, Frank; /Freiburg U.

    2012-05-17

    In this contribution, we will give a brief overview of the progress that has been achieved in the field of combining matrix elements and parton showers. We exemplify this by focusing on the case of electron-positron collisions and by reporting on recent developments as accomplished within the SHERPA event generation framework.

  12. Studies of double parton scattering in ATLAS

    CERN Document Server

    Lobodzinska, Ewelina Maria; The ATLAS collaboration

    2017-01-01

    In this contribution, Double Parton Scattering processes observed with the ATLAS detector at LHC are discussed. Results of five analyses are presented: production of W boson in association with 2 jets, production of $J/\\psi$ meson in association with W boson, $J/\\psi$ production with Z boson, $J/\\psi$ pair production and four jet events.

  13. Parton model in Lorentz invariant noncommutative space

    Science.gov (United States)

    Haghighat, M.; Ettefaghi, M. M.

    2004-08-01

    We consider the Lorentz invariant noncommutative QED and complete the Feynman rules for the theory up to the order θ2. In the Lorentz invariant version of the noncommutative QED the particles with fractional charges can be also considered. We show that in the parton model, even at the lowest order, the Bjorken scaling violates as ˜θ2Q4.

  14. The generalized method of moments as applied to the generalized gamma distribution

    Science.gov (United States)

    Ashkar, F.; Bobée, B.; Leroux, D.; Morisette, D.

    1988-09-01

    The generalized gamma (GG) distribution has a density function that can take on many possible forms commonly encountered in hydrologic applications. This fact has led many authors to study the properties of the distribution and to propose various estimation techniques (method of moments, mixed moments, maximum likelihood etc.). We discuss some of the most important properties of this flexible distribution and present a flexible method of parameter estimation, called the “generalized method of moments” (GMM) which combines any three moments of the GG distribution. The main advantage of this general method is that it has many of the previously proposed methods of estimation as special cases. We also give a general formula for the variance of the T-year event X T obtained by the GMM along with a general formula for the parameter estimates and also for the covariances and correlation coefficients between any pair of such estimates. By applying the GMM and carefully choosing the order of the moments that are used in the estimation one can significantly reduce the variance of T-year events for the range of return periods that are of interest.

  15. D-meson production according to the parton model and their detection in ALICE

    CERN Document Server

    Kalliokoski, Tuomo; Trzaska, Wladyslaw

    2007-01-01

    Modern understanding in particle physics is constructed over lay- ers and layers of work. Most of the work was done during last century, starting from the quantum mechanics. Modern theoretical basis is the parton model, which is constructed from three independent parts: distribution of momentum to partons inside hadron, partonic cross-sections from QCD and from fragmentation of parton to hadrons. All of these parts are discussed in this work. Future experiments are aiming for higher energies and/or greater number of intresting events than what previous experiments were capable to gain. Main example of this is LHC and ALICE-experiment on it in CERN. While simulations have benefited greatly from fast increase of computing power during last few decades. With the following assumptions, p$_t$ $>$ 1 GeV, fixed QCD scale Q = 5 GeV, massless quarks and only gluon-gluon channel in partonic cross-section and $\\delta$-function fragmentation, the lowest order simulations for production of D-meson with midrapidity y = 0 a...

  16. On Parameters Estimation of Lomax Distribution under General Progressive Censoring

    Directory of Open Access Journals (Sweden)

    Bander Al-Zahrani

    2013-01-01

    Full Text Available We consider the estimation problem of the probability S=P(Ydistribution based on general progressive censored data. The maximum likelihood estimator and Bayes estimators are obtained using the symmetric and asymmetric balanced loss functions. The Markov chain Monte Carlo (MCMC methods are used to accomplish some complex calculations. Comparisons are made between Bayesian and maximum likelihood estimators via Monte Carlo simulation study.

  17. Parton Rescattering Effect on the Charged Hadron Forward-Backward Multiplicity Correlation in pp Collisions at √s = 200 GeV*

    Institute of Scientific and Technical Information of China (English)

    闫玉良; 董保国; 周代梅; 李笑梅; 马海亮; 萨本豪

    2012-01-01

    The parton rescattering effect on the charged hadron forward-backward multiplicity correlation in pp collisions at √s =200 GeV is studied by a parton and hadron cascade model, PACIAE, based on the PYTHIA model. The calculated multiplicity and pseudorapidity distribution of the final state charged hadrons are well compared with the experimental data. It is found that the final state charged hadron pseudorapidity distribution is different from the initial state charged partons. The parton rescattering effect on the charged hadron forward-backward multiplicity correlation increases with the increasing parton rescattering strength in the center pseudorapidity region (|η| 〈 1). However, this effect becomes weaker in the outer pseudorapidity region (|η| 〉 1).

  18. Citation distribution profile in Brazilian journals of general medicine.

    Science.gov (United States)

    Lustosa, Luiggi Araujo; Chalco, Mario Edmundo Pastrana; Borba, Cecília de Melo; Higa, André Eizo; Almeida, Renan Moritz Varnier Rodrigues

    2012-01-01

    Impact factors are currently the bibliometric index most used for evaluating scientific journals. However, the way in which they are used, for instance concerning the study or journal types analyzed, can markedly interfere with estimate reliability. This study aimed to analyze the citation distribution pattern in three Brazilian journals of general medicine. This was a descriptive study based on numbers of citations of scientific studies published by three Brazilian journals of general medicine. The journals analyzed were São Paulo Medical Journal, Clinics and Revista da Associação Médica Brasileira. This survey used data available from the Institute for Scientific Information (ISI) platform, from which the total number of papers published in each journal in 2007-2008 and the number of citations of these papers in 2009 were obtained. From these data, the citation distribution was derived and journal impact factors (average number of citations) were estimated. These factors were then compared with those directly available from the ISI Journal of Citation Reports (JCR). Respectively, 134, 203 and 192 papers were published by these journals during the period analyzed. The observed citation distributions were highly skewed, such that many papers had few citations and a small percentage had many citations. It was not possible to identify any specific pattern for the most cited papers or to exactly reproduce the JCR impact factors. Use of measures like "impact factors", which characterize citations through averages, does not adequately represent the citation distribution in the journals analyzed.

  19. New simpler method of matching NLO corrections with parton shower Monte Carlo

    CERN Document Server

    Jadach, S; Sapeta, S; Siodmok, A; Skrzypek, M

    2016-01-01

    Next steps in development of the KrkNLO method of implementing NLO QCD corrections to hard processes in parton shower Monte Carlo programs are presented. This new method is a simpler alternative to other well-known approaches, such as MC@NLO and POWHEG. The KrkNLO method owns its simplicity to the use of parton distribution functions (PDFs) in a new, so-called Monte Carlo (MC), factorization scheme which was recently fully defined for the first time. Preliminary numerical results for the Higgs-boson production process are also presented.

  20. Similarity of the parton and the hadron spectra in chromodynamic jets

    Energy Technology Data Exchange (ETDEWEB)

    Azimov, Ya.I.; Dokshitser, Yu.L.; Troyan, S.I.; Khoze, V.A.

    1984-11-01

    A possible existence of local correspondence between parton and hadron distributions in hard processes( a local parton-hadron duality) is discussed. To test the local duality, prelimnary comparison with the data at the available energies have been performed. It is shown, in particular, that beyond the framework of the double-logarithmic approximation of the QCD perturbation theory the theoretical parton spectrum provides a reasonable description of ..pi../sup + -/ spectra in e/sup +/e/sup -/ annihilation at W > or approximately 20 GeV. A similarity is found for spectra of pions, kaons and protons. Further tests of the local duality, as well as chromodynamic coherent effects in jets, are proposed.

  1. Dijet azimuthal decorrelations at the LHC in the parton Reggeization approach

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, M.A. [Samarskij Gosudarstvennyj Univ., Samara (Russian Federation); Saleev, V.A.; Shipilova, A.V. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Samarskij Gosudarstvennyj Univ., Samara (Russian Federation)

    2013-04-15

    We study inclusive dijet azimuthal decorrelations in proton-proton collisions at the CERN LHC invoking the hypothesis of parton Reggeization in t-channel exchanges at high energies. In the parton Reggeization approach, the main contribution to the azimuthal angle difference between the two most energetic jets is due to the Reggeon-Reggeon-Particle-Particle scattering, when the fusion of two Reggeized gluons into a pair of Yang-Mills gluons dominates. Using a high-energy factorization scheme with the Kimber-Martin-Ryskin unintegrated parton distribution functions and the Fadin-Lipatov effective vertices we obtain good agreement of our calculations with recent measurements by the ATLAS and CMS Collaborations at the CERN LHC.

  2. Dijet azimuthal decorrelations at the LHC in the parton Reggeization approach

    Energy Technology Data Exchange (ETDEWEB)

    Nefedov, M.A. [Samarskij Gosudarstvennyj Univ., Samara (Russian Federation); Saleev, V.A.; Shipilova, A.V. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Samarskij Gosudarstvennyj Univ., Samara (Russian Federation)

    2013-04-15

    We study inclusive dijet azimuthal decorrelations in proton-proton collisions at the CERN LHC invoking the hypothesis of parton Reggeization in t-channel exchanges at high energies. In the parton Reggeization approach, the main contribution to the azimuthal angle difference between the two most energetic jets is due to the Reggeon-Reggeon-Particle-Particle scattering, when the fusion of two Reggeized gluons into a pair of Yang-Mills gluons dominates. Using a high-energy factorization scheme with the Kimber-Martin-Ryskin unintegrated parton distribution functions and the Fadin-Lipatov effective vertices we obtain good agreement of our calculations with recent measurements by the ATLAS and CMS Collaborations at the CERN LHC.

  3. Web-client based distributed generalization and geoprocessing

    Science.gov (United States)

    Wolf, E.B.; Howe, K.

    2009-01-01

    Generalization and geoprocessing operations on geospatial information were once the domain of complex software running on high-performance workstations. Currently, these computationally intensive processes are the domain of desktop applications. Recent efforts have been made to move geoprocessing operations server-side in a distributed, web accessible environment. This paper initiates research into portable client-side generalization and geoprocessing operations as part of a larger effort in user-centered design for the US Geological Survey's The National Map. An implementation of the Ramer-Douglas-Peucker (RDP) line simplification algorithm was created in the open source OpenLayers geoweb client. This algorithm implementation was benchmarked using differing data structures and browser platforms. The implementation and results of the benchmarks are discussed in the general context of client-side geoprocessing. (Abstract).

  4. Effects produced by multi-parton interactions and color reconnection in small systems

    Science.gov (United States)

    Cuautle, Eleazar; Ortiz, Antonio; Paić, Guy

    2016-12-01

    Multi-parton interactions and color reconnection can produce QGP-like effects in small systems, specifically, radial flow-like patterns. For pp collisions simulated with Pythia 8.212, in this work we investigate their effects on different observables like event multiplicity, event shapes and transverse momentum distributions.

  5. Development of plotting position for the general extreme value distribution

    Science.gov (United States)

    Kim, Sooyoung; Shin, Hongjoon; Joo, Kyoungwon; Heo, Jun-Haeng

    2012-12-01

    SummaryProbability plotting positions are used to graphically display the annual maximum rainfall or flood and to estimate the exceedance probabilities of those values. Therefore, the graphical approach using plotting positions has been applied in many hydrology and water resource engineering fields. The definition of unbiased plotting positions by Cunnane (1978) as the mean of the order statistics from reduced variates has influenced researchers to develop the plotting position of the probability distribution containing shape parameters. In this study, the plotting position formula for the general extreme value (GEV) distribution was derived by using the theoretical reduced variates of the GEV distribution for various sample sizes and shape parameters. To choose an appropriate plotting position formula, we examined eight plotting position formula types containing coefficients of skewness or squared coefficients of skewness in the numerator and/or denominator. In addition, the parameters of the plotting position formula for the GEV distribution were estimated by using a genetic optimization method known as the real-coded genetic algorithm (RGA). The accuracy of the derived plotting position formula for the GEV distribution was examined on the basis of the root mean square errors and relative bias between the theoretical reduced variates and those calculated from the derived and existing plotting position formulas. The derived plotting formula was found to be useful if the range of the shape parameter was within ±0.2.

  6. Generalized quantum counting algorithm for non-uniform amplitude distribution

    Science.gov (United States)

    Tan, Jianing; Ruan, Yue; Li, Xi; Chen, Hanwu

    2017-03-01

    We give generalized quantum counting algorithm to increase universality of quantum counting algorithm. Non-uniform initial amplitude distribution is possible due to the diversity of situations on counting problems or external noise in the amplitude initialization procedure. We give the reason why quantum counting algorithm is invalid on this situation. By modeling in three-dimensional space spanned by unmarked state, marked state and free state to the entire Hilbert space of n qubits, we find Grover iteration can be regarded as improper rotation in the space. This allows us to give formula to solve counting problem. Furthermore, we express initial amplitude distribution in the eigenvector basis of improper rotation matrix. This is necessary to obtain mathematical analysis of counting problem on various situations. Finally, we design four simulation experiments, the results of which show that compared with original quantum counting algorithm, generalized quantum counting algorithm wins great satisfaction from three aspects: (1) Whether initial amplitude distribution is uniform; (2) the diversity of situations on counting problems; and (3) whether phase estimation technique can get phase exactly.

  7. k-Generalized Statistics in Personal Income Distribution

    CERN Document Server

    Clementi, F; Kaniadakis, G

    2006-01-01

    The survival function $P_{>}(x)=\\exp_{\\kappa}(-\\beta x^{\\alpha})$, being $\\exp_{\\kappa}(x)=(\\sqrt{1+\\kappa^{2}x^{2}}+\\kappa x)^{1/\\kappa}$ the $\\kappa$-exponential function, with $x\\in\\mathbb{R}^{+}$, $\\alpha,\\beta>0$, and $\\kappa\\in[0,1)$, is considered in order to analyze the data on personal income distribution for Germany, Italy, and the United Kingdom. The above defined distribution is a continuous one-parameter deformation of the stretched exponential function $P_{>}(x)=\\exp(-\\beta x^{\\alpha})$\\textemdash to which reduces as $\\kappa$ approaches zero\\textemdash behaving in very different way in the $x\\to0$ and $x\\to\\infty$ regions. Its bulk is very close to the stretched exponential one, whereas its tail decays following the power-law $P_{>}(x)=(2\\kappa\\beta)^{-1/\\kappa}x^{-\\alpha/\\kappa}$. This makes the $\\kappa$-generalized function particularly suitable to describe simultaneously the income distribution among both the richest part and the vast majority of the population, generally fitting different cu...

  8. A Generalized Cauchy Distribution Framework for Problems Requiring Robust Behavior

    Science.gov (United States)

    Carrillo, Rafael E.; Aysal, Tuncer C.; Barner, Kenneth E.

    2010-12-01

    Statistical modeling is at the heart of many engineering problems. The importance of statistical modeling emanates not only from the desire to accurately characterize stochastic events, but also from the fact that distributions are the central models utilized to derive sample processing theories and methods. The generalized Cauchy distribution (GCD) family has a closed-form pdf expression across the whole family as well as algebraic tails, which makes it suitable for modeling many real-life impulsive processes. This paper develops a GCD theory-based approach that allows challenging problems to be formulated in a robust fashion. Notably, the proposed framework subsumes generalized Gaussian distribution (GGD) family-based developments, thereby guaranteeing performance improvements over traditional GCD-based problem formulation techniques. This robust framework can be adapted to a variety of applications in signal processing. As examples, we formulate four practical applications under this framework: (1) filtering for power line communications, (2) estimation in sensor networks with noisy channels, (3) reconstruction methods for compressed sensing, and (4) fuzzy clustering.

  9. A Generalized Cauchy Distribution Framework for Problems Requiring Robust Behavior

    Directory of Open Access Journals (Sweden)

    Carrillo RafaelE

    2010-01-01

    Full Text Available Statistical modeling is at the heart of many engineering problems. The importance of statistical modeling emanates not only from the desire to accurately characterize stochastic events, but also from the fact that distributions are the central models utilized to derive sample processing theories and methods. The generalized Cauchy distribution (GCD family has a closed-form pdf expression across the whole family as well as algebraic tails, which makes it suitable for modeling many real-life impulsive processes. This paper develops a GCD theory-based approach that allows challenging problems to be formulated in a robust fashion. Notably, the proposed framework subsumes generalized Gaussian distribution (GGD family-based developments, thereby guaranteeing performance improvements over traditional GCD-based problem formulation techniques. This robust framework can be adapted to a variety of applications in signal processing. As examples, we formulate four practical applications under this framework: (1 filtering for power line communications, (2 estimation in sensor networks with noisy channels, (3 reconstruction methods for compressed sensing, and (4 fuzzy clustering.

  10. VNI-4.1 Simulation of space-time evolution of $e^{+}e^{-}$.... A+B collisions with parton-cascades, parton-hadron conversion, final-state hadron cascades

    CERN Document Server

    Kinder-Geiger, Klaus; Srivastava, D K; Geiger, Klaus; Longacre, Ron; Srivastava, Dinesh K.

    1997-01-01

    VNI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. It uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme, as well as the development of hadron cascades after hadronization. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time-development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position-space, momentum-space and color-space. The parton-evolution is described in terms of a space-time generalization of the familiar momentum-space description of multiple (semi)hard interactions in QCD, involving 2 -> 2 parton collisions, 2 -> 1 parton fusion processes, and 1 -> 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is trea...

  11. Generalized Exponential Distribution in Flood Frequency Analysis for Polish Rivers

    Science.gov (United States)

    Markiewicz, Iwona; Strupczewski, Witold G.; Bogdanowicz, Ewa; Kochanek, Krzysztof

    2015-01-01

    Many distributions have been used in flood frequency analysis (FFA) for fitting the flood extremes data. However, as shown in the paper, the scatter of Polish data plotted on the moment ratio diagram shows that there is still room for a new model. In the paper, we study the usefulness of the generalized exponential (GE) distribution in flood frequency analysis for Polish Rivers. We investigate the fit of GE distribution to the Polish data of the maximum flows in comparison with the inverse Gaussian (IG) distribution, which in our previous studies showed the best fitting among several models commonly used in FFA. Since the use of a discrimination procedure without the knowledge of its performance for the considered probability density functions may lead to erroneous conclusions, we compare the probability of correct selection for the GE and IG distributions along with the analysis of the asymptotic model error in respect to the upper quantile values. As an application, both GE and IG distributions are alternatively assumed for describing the annual peak flows for several gauging stations of Polish Rivers. To find the best fitting model, four discrimination procedures are used. In turn, they are based on the maximized logarithm of the likelihood function (K procedure), on the density function of the scale transformation maximal invariant (QK procedure), on the Kolmogorov-Smirnov statistics (KS procedure) and the fourth procedure based on the differences between the ML estimate of 1% quantile and its value assessed by the method of moments and linear moments, in sequence (R procedure). Due to the uncertainty of choosing the best model, the method of aggregation is applied to estimate of the maximum flow quantiles. PMID:26657239

  12. Selecting series size where the generalized Pareto distribution best fits

    Science.gov (United States)

    Ben-Zvi, Arie

    2016-10-01

    Rates of arrival and magnitudes of hydrologic variables are frequently described by the Poisson and the generalized Pareto (GP) distributions. Variations of their goodness-of-fit to nested series are studied here. The variable employed is depth of rainfall events at five stations of the Israel Meteorological Service. Series sizes range from about 50 (number of years on records) to about 1000 (total number of recorded events). The goodness-of-fit is assessed by the Anderson-Darling test. Three versions of this test are applied here. These are the regular two-sided test (of which the statistic is designated here by A2), the upper one-sided test (UA2) and the adaptation to the Poisson distribution (PA2). Very good fits, with rejection significance levels higher than 0.5 for A2 and higher than 0.25 for PA2, are found for many series of different sizes. Values of the shape parameter of the GP distribution and of the predicted rainfall depths widely vary with series size. Small coefficients of variation are found, at each station, for the 100-year rainfall depths, predicted through the series with very good fit of the GP distribution. Therefore, predictions through series of very good fit appear more consistent than through other selections of series size. Variations of UA2, with series size, are found narrower than those of A2. Therefore, it is advisable to predict through the series of low UA2. Very good fits of the Poisson distribution to arrival rates are found for series with low UA2. But, a reversed relation is not found here. Thus, the model of Poissonian arrival rates and GP distribution of magnitudes suits here series with low UA2. It is recommended to predict through the series, to which the lowest UA2 is obtained.

  13. Generalized Exponential Distribution in Flood Frequency Analysis for Polish Rivers.

    Science.gov (United States)

    Markiewicz, Iwona; Strupczewski, Witold G; Bogdanowicz, Ewa; Kochanek, Krzysztof

    2015-01-01

    Many distributions have been used in flood frequency analysis (FFA) for fitting the flood extremes data. However, as shown in the paper, the scatter of Polish data plotted on the moment ratio diagram shows that there is still room for a new model. In the paper, we study the usefulness of the generalized exponential (GE) distribution in flood frequency analysis for Polish Rivers. We investigate the fit of GE distribution to the Polish data of the maximum flows in comparison with the inverse Gaussian (IG) distribution, which in our previous studies showed the best fitting among several models commonly used in FFA. Since the use of a discrimination procedure without the knowledge of its performance for the considered probability density functions may lead to erroneous conclusions, we compare the probability of correct selection for the GE and IG distributions along with the analysis of the asymptotic model error in respect to the upper quantile values. As an application, both GE and IG distributions are alternatively assumed for describing the annual peak flows for several gauging stations of Polish Rivers. To find the best fitting model, four discrimination procedures are used. In turn, they are based on the maximized logarithm of the likelihood function (K procedure), on the density function of the scale transformation maximal invariant (QK procedure), on the Kolmogorov-Smirnov statistics (KS procedure) and the fourth procedure based on the differences between the ML estimate of 1% quantile and its value assessed by the method of moments and linear moments, in sequence (R procedure). Due to the uncertainty of choosing the best model, the method of aggregation is applied to estimate of the maximum flow quantiles.

  14. Proper definition and evolution of generalized transverse momentum dependent distributions

    Directory of Open Access Journals (Sweden)

    Miguel G. Echevarria

    2016-08-01

    Full Text Available We consider one of the most fundamental sets of hadronic matrix elements, namely the generalized transverse momentum dependent distributions (GTMDs, and argue that their existing definitions lack proper evolution properties. By exploiting the similarity of GTMDs with the much better understood transverse momentum distributions, we argue that the existing definitions of GTMDs have to include an additional dependence on soft gluon radiation in order to render them properly defined. With this, we manage to obtain the evolution kernel of all (unpolarized quark and gluon GTMDs, which turns out to be spin independent. As a byproduct, all large logarithms can be resummed up to next-to-next-to-leading-logarithmic accuracy with the currently known perturbative ingredients.

  15. Proper definition and evolution of generalized transverse momentum dependent distributions

    Energy Technology Data Exchange (ETDEWEB)

    Echevarria, Miguel G., E-mail: mgechevarria@icc.ub.edu [Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Idilbi, Ahmad, E-mail: ahmad.idilbi@wayne.edu [Department of Physics, Wayne State University, Detroit, MI, 48202 (United States); Kanazawa, Koichi, E-mail: koichi.kanazawa@temple.edu [Department of Physics, SERC, Temple University, Philadelphia, PA 19122 (United States); Lorcé, Cédric, E-mail: cedric.lorce@polytechnique.edu [Centre de Physique Théorique, École polytechnique, CNRS, Université Paris-Saclay, F-91128 Palaiseau (France); Metz, Andreas, E-mail: metza@temple.edu [Department of Physics, SERC, Temple University, Philadelphia, PA 19122 (United States); Pasquini, Barbara, E-mail: barbara.pasquini@pv.infn.it [Dipartimento di Fisica, Università degli Studi di Pavia, I-27100 Pavia (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, I-27100 Pavia (Italy); Schlegel, Marc, E-mail: marc.schlegel@uni-tuebingen.de [Institute for Theoretical Physics, Tübingen University, Auf der Morgenstelle 14, 72076 Tübingen (Germany)

    2016-08-10

    We consider one of the most fundamental sets of hadronic matrix elements, namely the generalized transverse momentum dependent distributions (GTMDs), and argue that their existing definitions lack proper evolution properties. By exploiting the similarity of GTMDs with the much better understood transverse momentum distributions, we argue that the existing definitions of GTMDs have to include an additional dependence on soft gluon radiation in order to render them properly defined. With this, we manage to obtain the evolution kernel of all (un)polarized quark and gluon GTMDs, which turns out to be spin independent. As a byproduct, all large logarithms can be resummed up to next-to-next-to-leading-logarithmic accuracy with the currently known perturbative ingredients.

  16. On the Limit Distribution of Lower Extreme Generalized Order Statistics

    Indian Academy of Sciences (India)

    H M Barakat; Magdy E El-Adll

    2012-05-01

    In a wide subclass of generalized order statistics $(gOs)$, which contains most of the known and important models of ordered random variables, weak convergence of lower extremes are developed. A recent result of extreme value theory of $m-gOs$ (as well as the classical extreme value theory of ordinary order statistics) yields three types of limit distributions that are possible in case of linear normalization. In this paper a similar classification of limit distributions holds for extreme $gOs$, where the parameters $_j,j=1,\\ldots,n$, are assumed to be pairwise different. Two illustrative examples are given to demonstrate the practical importance for some of the obtained results.

  17. Citation distribution profile in Brazilian journals of general medicine

    Directory of Open Access Journals (Sweden)

    Luiggi Araujo Lustosa

    Full Text Available CONTEXT AND OBJECTIVE: Impact factors are currently the bibliometric index most used for evaluating scientific journals. However, the way in which they are used, for instance concerning the study or journal types analyzed, can markedly interfere with estimate reliability. This study aimed to analyze the citation distribution pattern in three Brazilian journals of general medicine. DESIGN AND SETTING: This was a descriptive study based on numbers of citations of scientific studies published by three Brazilian journals of general medicine. METHODS: The journals analyzed were São Paulo Medical Journal, Clinics and Revista da Associação Médica Brasileira. This survey used data available from the Institute for Scientific Information (ISI platform, from which the total number of papers published in each journal in 2007-2008 and the number of citations of these papers in 2009 were obtained. From these data, the citation distribution was derived and journal impact factors (average number of citations were estimated. These factors were then compared with those directly available from the ISI Journal of Citation Reports (JCR. RESULTS: Respectively, 134, 203 and 192 papers were published by these journals during the period analyzed. The observed citation distributions were highly skewed, such that many papers had few citations and a small percentage had many citations. It was not possible to identify any specific pattern for the most cited papers or to exactly reproduce the JCR impact factors. CONCLUSION: Use of measures like "impact factors", which characterize citations through averages, does not adequately represent the citation distribution in the journals analyzed.

  18. Topology Identification of General Dynamical Network with Distributed Time Delays

    Institute of Scientific and Technical Information of China (English)

    WU Zhao-Yan; FU Xin-Chu

    2009-01-01

    General dynamical networks with distributed time delays are studied. The topology of the networks are viewed as unknown parameters, which need to be identified. Some auxiliary systems (also called the network estimators)are designed to achieve this goal. Both linear feedback control and adaptive strategy are applied in designing these network estimators. Based on linear matrix inequalities and the Lyapunov function method, the sufficient condition for the achievement of topology identification is obtained. This method can also better monitor the switching topology of dynamical networks. Illustrative examples are provided to show the effectiveness of this method.

  19. Modeling the brain morphology distribution in the general aging population

    Science.gov (United States)

    Huizinga, W.; Poot, D. H. J.; Roshchupkin, G.; Bron, E. E.; Ikram, M. A.; Vernooij, M. W.; Rueckert, D.; Niessen, W. J.; Klein, S.

    2016-03-01

    Both normal aging and neurodegenerative diseases such as Alzheimer's disease cause morphological changes of the brain. To better distinguish between normal and abnormal cases, it is necessary to model changes in brain morphology owing to normal aging. To this end, we developed a method for analyzing and visualizing these changes for the entire brain morphology distribution in the general aging population. The method is applied to 1000 subjects from a large population imaging study in the elderly, from which 900 were used to train the model and 100 were used for testing. The results of the 100 test subjects show that the model generalizes to subjects outside the model population. Smooth percentile curves showing the brain morphology changes as a function of age and spatiotemporal atlases derived from the model population are publicly available via an interactive web application at agingbrain.bigr.nl.

  20. Double parton correlations in Light-Front constituent quark models

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2015-01-01

    Full Text Available Double parton distribution functions (dPDF represent a tool to explore the 3D proton structure. They can be measured in high energy proton-proton and proton nucleus collisions and encode information on how partons inside a proton are correlated among each other. dPFDs are studied here in the valence quark region, by means of a constituent quark model, where two particle correlations are present without any additional prescription. This framework allows to understand the dynamical origin of the correlations and to clarify which, among the features of the results, are model independent. Use will be made of a relativistic light-front scheme, able to overcome some drawbacks of the previous calculation. Transverse momentum correlations, due to the exact treatment of the boosts, are predicted and analyzed. The role of spin correlations is also shown. Due to the covariance of the approach, some symmetries of the dPDFs are seen unambigously. For the valence sector, also the study of the QCD evolution of the model results, which can be performed safely thanks to the property of good support, has been also completed.

  1. CMS Underlying Event and Double Parton Scattering Monte Carlo Tunes

    CERN Document Server

    AUTHOR|(CDS)2079608

    2016-01-01

    Three new PYTHIA 8 underlying event (UE) tunes are presented, one using the CTEQ6L1 parton distribution function (PDF), one using HERAPDF1.5LO, and one using the NNPDF2.3LO PDF; two new PYTHIA 6 UE tunes, one for the CTEQ6L1 PDF and one for the HERAPDF1.5LO, and one new HERWIG++ UE tune for the CTEQ6L1 PDF are also available. Simultaneous fits to CDF UE data at center-of-mass energies of 0.3, 0.9, and 1.96 TeV, together with CMS UE data at 7 TeV, check the UE models and constrain their parameters, providing thereby more precise predictions for proton-proton collisions at 13 TeV. In addition, several new double parton scattering (DPS) tunes are examined in order to investigate if the values of the parameters from fits to UE observables are consistent with the values determined from fitting DPS-sensitive observables. It is also examined how well the new UE tunes predict minimum bias (MB) events, jet, and Drell-Yan observables, as well as MB and UE observables at 13 TeV.

  2. Parton Cascade Description of Heavy-Ion Collisions at CERN?

    CERN Document Server

    Kinder-Geiger, Klaus

    1998-01-01

    There seems to be a general consensus now that a first glimpse of a QGP-like effect has become visible in the beautiful NA50 data on J/\\psi production and the `anomalous supression' phenomenon. On the other hand, it is still widely believed that the dynamics of heavy-ion collisions at CERN SPS energy is predominantly governed by soft, non-perturbative physics. This is ironic: after all, it is unlikely that a QGP could be formed if the underlying dynamics were essentyially soft, rather than that it requires intense quark-gluon production with sufficient cascade-like reinteractions which drive the matter to large density and equilibrium. Therefore, I advocate in this contribution that for ultra-relativistic nucleus-nucleus collisions a description based on the pQCD interactions and cascade evolution of involved partons can and should be used, owing to the claim that short-range parton interactions play an important role at sufficiently high beam energies, including CERN energy sqrt(s) = 20 A GeV. Here mini-jet ...

  3. Bayesian inference and life testing plans for generalized exponential distribution

    Institute of Scientific and Technical Information of China (English)

    KUNDU; Debasis; PRADHAN; Biswabrata

    2009-01-01

    Recently generalized exponential distribution has received considerable attentions.In this paper,we deal with the Bayesian inference of the unknown parameters of the progressively censored generalized exponential distribution.It is assumed that the scale and the shape parameters have independent gamma priors.The Bayes estimates of the unknown parameters cannot be obtained in the closed form.Lindley’s approximation and importance sampling technique have been suggested to compute the approximate Bayes estimates.Markov Chain Monte Carlo method has been used to compute the approximate Bayes estimates and also to construct the highest posterior density credible intervals.We also provide different criteria to compare two different sampling schemes and hence to ?nd the optimal sampling schemes.It is observed that ?nding the optimum censoring procedure is a computationally expensive process.And we have recommended to use the sub-optimal censoring procedure,which can be obtained very easily.Monte Carlo simulations are performed to compare the performances of the different methods and one data analysis has been performed for illustrative purposes.

  4. Tolerating Correlated Failures for Generalized Cartesian Distributions via Bipartite Matching

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Nawab; Krishnamoorthy, Sriram; Halappanavar, Mahantesh; Daily, Jeffrey A.

    2011-05-05

    Faults are expected to play an increasingly important role in how algorithms and applications are designed to run on future extreme-scale systems. A key ingredient of any approach to fault tolerance is effective support for fault tolerant data storage. A typical application execution consists of phases in which certain data structures are modified while others are read-only. Often, read-only data structures constitute a large fraction of total memory consumed. Fault tolerance for read-only data can be ensured through the use of checksums or parities, without resorting to expensive in-memory duplication or checkpointing to secondary storage. In this paper, we present a graph-matching approach to compute and store parity data for read-only matrices that are compatible with fault tolerant linear algebra (FTLA). Typical approaches only support blocked data distributions with each process holding one block with the parity located on additional processes. The matrices are assumed to be blocked by a cartesian grid with each block assigned to a process. We consider a generalized distribution in which each process can be assigned arbitrary blocks. We also account for the fact that multiple processes might be part of the same failure unit, say an SMP node. The flexibility enabled by our novel application of graph matching extends fault tolerance support to data distributions beyond those supported by prior work. We evaluate the matching implementations and cost to compute the parity and recover lost data, demonstrating the low overhead incurred by our approach.

  5. A Comparison of Generalized Hyperbolic Distribution Models for Equity Returns

    Directory of Open Access Journals (Sweden)

    Virginie Konlack Socgnia

    2014-01-01

    Full Text Available We discuss the calibration of the univariate and multivariate generalized hyperbolic distributions, as well as their hyperbolic, variance gamma, normal inverse Gaussian, and skew Student’s t-distribution subclasses for the daily log-returns of seven of the most liquid mining stocks listed on the Johannesburg Stocks Exchange. To estimate the model parameters from historic distributions, we use an expectation maximization based algorithm for the univariate case and a multicycle expectation conditional maximization estimation algorithm for the multivariate case. We assess the goodness of fit statistics using the log-likelihood, the Akaike information criterion, and the Kolmogorov-Smirnov distance. Finally, we inspect the temporal stability of parameters and note implications as criteria for distinguishing between models. To better understand the dependence structure of the stocks, we fit the MGHD and subclasses to both the stock returns and the two leading principal components derived from the price data. While the MGHD could fit both data subsets, we observed that the multivariate normality of the stock return residuals, computed by removing shared components, suggests that the departure from normality can be explained by the structure in the common factors.

  6. Generalized Poisson-Lindely Distribution in Promotion Time Cure Model

    Directory of Open Access Journals (Sweden)

    Ahmad Reza Baghestani

    2014-12-01

    Full Text Available 1024x768 Long-term survival analysis has been improved in the last decade and most of the models concentrate on the promotion time cure model that proposed by Chen (1999. These models are based on the distribution of latent variable N, number of initiated node cells. In this paper we proposed a Generalized Poisson-Lindely distribution that is another option instead of Negative Binomial distribution when there is overdispersion. The results indicated a better fitness compared to others, because of its more flexibility. Parameter estimation has been done by Bayesian approach, in a real data set and a simulation study has shown the advantages of proposed model. Normal 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

  7. Parton cascade description of relativistic heavy-ion collisions at CERN SPS energies?

    CERN Document Server

    Kinder-Geiger, Klaus; Geiger, Klaus; Srivastava, Dinesh Kumar

    1997-01-01

    We examine Pb+Pb collisions at CERN SPS energy 158 A GeV, by employing the earlier developed and recently refined parton-cascade/cluster-hadronization model and its Monte Carlo implementation. This space-time model involves the dynamical interplay of perturbative QCD parton production and evolution, with non-perturbative parton-cluster formation and hadron production through cluster decays. Using computer simulations, we are able to follow the entwined time-evolution of parton and hadron degrees of freedom in both position and momentum space, from the instant of nuclear overlap to the final yield of particles. We present and discuss results for the multiplicity distributions, which agree well with the measured data from the CERN SPS, including those for K mesons. The transverse momentum distributions of the produced hadrons are also found to be in good agreement with the preliminary data measured by the NA49 and the WA98 collaboration for the collision of lead nuclei at the CERN SPS. The analysis of the time ...

  8. Partonic Energy Loss and the Drell-Yan Process

    OpenAIRE

    2002-01-01

    We examine the current status of the extraction of the rate of partonic energy loss in nuclei from A dependent data. The advantages and difficulties of using the Drell-Yan process to measure the energy loss of a parton traversing a cold nuclear medium are discussed. The prospects of using relatively low energy proton beams for a definitive measurement of partonic energy loss are presented.

  9. Real-time dynamics of parton-hadron conversion

    CERN Document Server

    Ellis, Jonathan Richard; Ellis, John; Geiger, Klaus

    1995-01-01

    We propose a new and universal approach to the hadronization problem that incorporates both perturbative QCD and effective field theory in their respective domains of validity and that models the transition between them in analogy to the finite temperature QCD phase transition. Using techniques of quantum kinetic theory, we formulate a real-time description in momentum and position space. The approach is applied to the evolution of fragmenting q\\bar q and gg jets as the system evolves from the initial 2-jet, via parton multiplication and cluster formation, to the final yield of hadrons. We investigate time scale of the transition, energy dependence, cluster size and mass distributions, and compare our results for particle production and Bose-Einstein correlations with experimental data for e^+e^-\\rightarrow hadrons. An interesting possibility to extract the space-time evolution of the system from Bose enhancement measurements is suggested.

  10. Nucleon sea parton densities. Differences for neutrinos and muons

    Energy Technology Data Exchange (ETDEWEB)

    Barone, V. (Dipt. di Fisica, Univ. di Perugia (Italy) Ist. Nazionale di Fisica Nucleare, Perugia (Italy)); Genovese, M.; Predazzi, E. (Dipt. di Fisica Teorica, Univ. Turin (Italy) Ist. Nazionale di Fisica Nucleare, Turin (Italy)); Nikolaev, N.N. (Dipt. di Fisica Teorica, Univ. Turin (Italy) Ist. Nazionale di Fisica Nucleare, Turin (Italy) European Branch of L.D. Landau Inst., ISI Foundation, Turin (Italy)); Zakharov, B.G. (Inst. of Nuclear Research, Moscow State Univ. (Russia))

    1991-10-10

    The nucleon sea parton distributions probed by muons and neutrinos are different since excitation of santi s, canti c pairs by muons and canti s, santi c pairs by neutrinos have different mass thresholds. Natural starting points for the structure functions are c{sub {nu}}(x, Q{sup 2}) {approx equal} s{sub {nu}}(x, Q{sup 2}), in {nu} (anti {nu}) interactions and c{sub {mu}}(x, Q{sup 2})<

  11. Improved Parton Showers at Large Transverse Momenta

    CERN Document Server

    Corke, Richard

    2010-01-01

    Several methods to improve the parton-shower description of hard processes by an injection of matrix-element-based information have been presented over the years. In this article we study (re)weighting schemes for the first/hardest emission. One objective is to provide a consistent matching of the POWHEG next-to-leading order generator to the Pythia shower algorithms. Another is to correct the default behaviour of these showers at large transverse momenta, based on a comparison with real-emission matrix elements.

  12. Study of non-collinear parton dynamics in the prompt photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Lipatov, A.V.; Zotov, N.P. [Lomonosov Moscow State Univ. (Russian Federation). Skobeltsyn Inst. of Nuclear Physics

    2010-04-15

    We investigate the prompt photon photoproduction at HERA within the framework of k{sub T} - factorization QCD approach. Our consideration is based on the off-shell matrix elements for the underlying partonic subprocesses. The unintegrated parton densities in a proton and in a photon are determined using the Kimber-Martin-Ryskin (KMR) prescription. Additionally, we use the CCFM-evolved unintegrated gluon as well as valence and sea quark distributions in a proton. A conservative error analysis is performed. Both inclusive and associated with the hadronic jet production rates are investigated. The theoretical results are compared with the recent experimental data taken by the H1 and ZEUS collaborations. We study also the specific kinematical properties of the photon-jet system which are strongly sensitive to the transverse momentum of incoming partons. Using the KMR scheme, the contribution from the quarks emerging from the earlier steps of the parton evolution is estimated and found to be of 15 - 20% approximately. (orig.)

  13. Broadening of Transverse Momentum of Partons Propagating through a Medium

    CERN Document Server

    Johnson, M B; Tarasov, A V

    2001-01-01

    Broadening of the transverse momentum of a parton propagating through a medium is treated using the color dipole formalism, which has the advantage of being a well developed phenomenology in deep-inelastic scattering and soft processes. Within this approach, nuclear broadening should be treated as color filtering, i.e. absorption of large-size dipoles leading to diminishing (enlarged) transverse separation (momentum). We also present a more intuitive derivation based on the classic scattering theory of Moli\\`ere. This derivation helps to understand the origin of the dipole cross section, part of which comes from attenuation of the quark, while another part is due to multiple interactions of the quark. It also demonstrates that the lowest-order rescattering term provides an A-dependence very different from the generally accepted A^{1/3} behavior. The effect of broadening increases with energy, and we evaluate it using different phenomenological models for the unintegrated gluon density. Although the process is...

  14. Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon

    CERN Document Server

    Kanazawa, K; Metz, A; Pasquini, B; Schlegel, M

    2014-01-01

    Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. Here we focus on two twist-2 GTMDs which are denoted by $F_{1,4}$ and $G_{1,1}$ in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of $F_{1,4}$ and $G_{1,1}$ has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the two GTMDs in the scalar diquark model and in the quark-target model, where we also explicitly check the relation to orbital angular momentum. In addition, we compute $F_{1,4}$ and $G_{1,1}$ at large transverse momentum in perturbative Quantum Chromodynamics and show that they are nonzero.

  15. Minijet Initial Conditions For Non-Equilibrium Parton Evolution at RHIC and LHC

    CERN Document Server

    Cooper, F; Nayak, G C

    2003-01-01

    An important ingredient for the non-equilibrium evolution of partons at RHIC and LHC is to have some physically reasonable initial conditions for the single particle phase space distribution functions for the partons. We consider several plausible parametrizations of initial conditions for the single particle distribution function f /sub i/ (x, p) and fix the parameters by matching integral f (x, p)p /sup mu / d sigma /sub mu / to the invariant momentum space semi-hard parton distributions obtained using perturbative QCD (pQCD), as well as fitting low order moments of the distribution function. We consider parametrizations of fi (x, p) with both boost invariant and boost non-invariant assumptions. We determine the initial number density, energy density and the corresponding (effective) temperature of the minijet plasma at RHIC and LHC energies. For a boost non- invariant minijet phase-space distribution function we obtain ~ 30 (140)/fm/sup 3/ as the initial number density, ~ 50(520) GeV/fm/sup 3 / as the init...

  16. Multivariate Generalizations of the Multiplicative Binomial Distribution: Introducing the MM Package

    OpenAIRE

    Altham, Pat M. E.; Robin K. S. Hankin

    2012-01-01

    We present two natural generalizations of the multinomial and multivariate binomial distributions, which arise from the multiplicative binomial distribution of Altham (1978). The resulting two distributions are discussed and we introduce an R package, MM, which includes associated functionality.

  17. Parton-hadron dynamics in heavy-ion collisions

    CERN Document Server

    Bratkovskaya, E L; Cassing, W; Konchakovski, V P; Linnyk, O; Marty, R; Berrehrah, H

    2013-01-01

    The dynamics of partons and hadrons in relativistic nucleus-nucleus collisions is analyzed within the novel Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model for the partonic phase (DQPM) including a dynamical hadronization scheme. The PHSD approach is applied to nucleus-nucleus collisions from low SPS to LHC energies. The traces of partonic interactions are found in particular in the elliptic flow of hadrons and in their transverse mass spectra. We investigate also the equilibrium properties of strongly-interacting infinite parton-hadron matter characterized by transport coefficients such as shear and bulk viscosities and the electric conductivity in comparison to lattice QCD results.

  18. Upsilonium Polarization as a Touchstone in Understanding the Parton Dynamics in QCD

    CERN Document Server

    Baranov, S P

    2008-01-01

    In the framework of the $k_T$-factorization approach, the production of Upsilon mesons at the Fermilab Tevatron is considered, and the comparisions of calculated $p_T$-distributions and spin alignment parameter $\\alpha$ with the D0 experimental data are shown. We argue that measuring the double cross section and the polarization of upsilonium states can serve as a crucial test discriminating two competing theoretical approaches to parton dynamics in QCD.

  19. Nuclear and partonic dynamics in the EMC effect at Next-to-Next-to-Leading order

    CERN Document Server

    Tehrani, S Atashbar

    2014-01-01

    We study in details the parameterizations of the nuclear parton distributions at the next-to-next-to-leading order (NNLO) of $\\alpha_s$. In low $x$ and $Q_0^2$, we observe negative gluon distribution at this order which signals the saturation condition or the quark-gluon plasma condition. Our study also shows the gluon distribution at (NNLO) is less than next-to-leading order (NLO) of $\\alpha_s$, and the sea quark distribution at (NNLO) is larger than (NLO).

  20. A generalization information management system applied to electrical distribution

    Energy Technology Data Exchange (ETDEWEB)

    Geisler, K.I.; Neumann, S.A.; Nielsen, T.D.; Bower, P.K. (Empros Systems International (US)); Hughes, B.A.

    1990-07-01

    This article presents a system solution approach that meets the requirements being imposed by industry trends and the electric utility customer. Specifically, the solution addresses electric distribution management systems. Electrical distribution management is a particularly well suited area of application because it involves a high diversity of tasks, which are currently supported by a proliferation of automated islands. Islands of automation which currently exist include (among others) distribution operations, load management, automated mapping, facility management, work order processing, and planning.

  1. WW Same-Sign Double Parton Scattering

    CERN Document Server

    Fascione, Eleanor

    2016-01-01

    Data collected by the CMS detector of 13 TeV centre of mass proton-proton collisions, provided during run 2 of the LHC, constitutes an integrated luminosity of $12.9\\,\\mathrm{fb}^{-1}$. This provides a tool to probe a previously unmeasured process, double parton scattering (DPS) in same-sign WW. Leptonic decay to a muon and associated neutrino was selected for each W boson. In this manner complicated backgrounds were all but negated. A BDT was trained against the most kinematically similar background, and appropriate statistical measures were used to estimate the contribution of fake leptons from W+jets and, to a lesser extent, ttbar. An expected uncertainty on the signal of 52\\% was extracted, or $2 \\sigma$ significance. An in-progress analysis will determine a limit on the production cross section.

  2. Dijet cross sections and parton densities in diffractive DIS at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Aktas, A. [DESY, Hamburg (Germany); Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)

    2007-08-15

    Differential dijet cross sections in diffractive deep-inelastic scattering are measured with the H1 detector at HERA using an integrated luminosity of 51.5 pb{sup -1}. The selected events are of the type ep {yields} eXY, where the system X contains at least two jets and is well separated in rapidity from the low mass proton dissociation system Y. The dijet data are compared with QCD predictions at next-to-leading order based on diffractive parton distribution functions previously extracted from measurements of inclusive diffractive deepinelastic scattering. The prediction describes the dijet data well at low and intermediate z{sub P} (the fraction of the momentum of the diffractive exchange carried by the parton entering the hard interaction) where the gluon density is well determined from the inclusive diffractive data, supporting QCD factorisation. A new set of diffractive parton distribution functions is obtained through a simultaneous fit to the diffractive inclusive and dijet cross sections. This allows for a precise determination of both the diffractive quark and gluon distributions in the range 0.05

  3. Transverse-Distance Dependent Parton Densities in the Large-$x$ Regime

    CERN Document Server

    Cherednikov, I O

    2014-01-01

    QCD factorization approach in the field-theoretic description of the semi-inclusive hadronic processes in the large Bjorken $x$ approximation implies extraction of the three-dimensional parton distribution functions as a convolution of a collinear jet function and soft transverse-distance dependent (TDD) function defined as a vacuum average of a partially light-like Wilson loop. The soft function can be interpreted, therefore, as an element of generalized loop space. A class of classically conformal-invariant transformations of the elements of this space is generated by the non-local area derivative operator which corresponds to a diffeomorphism in the loop space and determines equations of motion, the latter being associated with the rapidity evolution of the soft TDD functions. We propose a large-$x$ TDD factorization framework and discuss practical applications of this approach to the phenomenology of the TDDs accessible in future experimental programs at the Jefferson Lab 12 GeV and the Electron-Ion Colli...

  4. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED "GLOBAL ANALYSIS OF POLARIZED PARTON DESTRIBUTIONS IN THE RHIC ERA" (VOLUME 86).

    Energy Technology Data Exchange (ETDEWEB)

    DESHPANDE,A.; VOGELSANG, W.

    2007-10-08

    The determination of the polarized gluon distribution is a central goal of the RHIC spin program. Recent achievements in polarization and luminosity of the proton beams in RHIC, has enabled the RHIC experiments to acquire substantial amounts of high quality data with polarized proton beams at 200 and 62.4 GeV center of mass energy, allowing a first glimpse of the polarized gluon distribution at RHIC. Short test operation at 500 GeV center of mass energy has also been successful, indicating absence of any fundamental roadblocks for measurements of polarized quark and anti-quark distributions planned at that energy in a couple of years. With this background, it has now become high time to consider how all these data sets may be employed most effectively to determine the polarized parton distributions in the nucleon, in general, and the polarized gluon distribution, in particular. A global analysis of the polarized DIS data from the past and present fixed target experiments jointly with the present and anticipated RHIC Spin data is needed.

  5. Slepton pair production in association with a jet: NLO-QCD corrections and parton-shower effects

    CERN Document Server

    Jager, Barbara; Thier, Stephan

    2014-01-01

    We present a calculation of the next-to-leading order QCD corrections to slepton pair production in association with a jet at the LHC together with their implementation in the POWHEG BOX. For the simulation of parton-shower effects and the decays of the sleptons we employ the multi-purpose Monte-Carlo program PYTHIA. We discuss the impact of next-to-leading order QCD corrections on experimentally accessible distributions and illustrate how the parton shower can modify observables that are sensitive to QCD radiation effects. Having full control on the hard jet in the process, we provide precise predictions also for monojet analyses.

  6. Double parton scattering: A study of the effective cross section within a Light-Front quark model

    Directory of Open Access Journals (Sweden)

    Matteo Rinaldi

    2016-01-01

    Full Text Available We present a calculation of the effective cross section σeff, an important ingredient in the description of double parton scattering in proton–proton collisions. Our theoretical approach makes use of a Light-Front quark model as a framework to calculate the double parton distribution functions at low-resolution scale. QCD evolution is implemented to reach the experimental scale. The obtained values of σeff in the valence region are consistent with the present experimental scenario, in particular with the sets of data which include the same kinematical range. However the result of the complete calculation shows a dependence of σeff on xi, a feature not easily seen in the available data, probably because of their low accuracy. Measurements of σeff in restricted xi regions are addressed to obtain indications on double parton correlations, a novel and interesting aspect of the three dimensional structure of the nucleon.

  7. An analytic parton shower. Algorithms, implementation and validation

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Sebastian

    2012-06-15

    The realistic simulation of particle collisions is an indispensable tool to interpret the data measured at high-energy colliders, for example the now running Large Hadron Collider at CERN. These collisions at these colliders are usually simulated in the form of exclusive events. This thesis focuses on the perturbative QCD part involved in the simulation of these events, particularly parton showers and the consistent combination of parton showers and matrix elements. We present an existing parton shower algorithm for emissions off final state partons along with some major improvements. Moreover, we present a new parton shower algorithm for emissions off incoming partons. The aim of these particular algorithms, called analytic parton shower algorithms, is to be able to calculate the probabilities for branchings and for whole events after the event has been generated. This allows a reweighting procedure to be applied after the events have been simulated. We show a detailed description of the algorithms, their implementation and the interfaces to the event generator WHIZARD. Moreover we discuss the implementation of a MLM-type matching procedure and an interface to the shower and hadronization routines from PYTHIA. Finally, we compare several predictions by our implementation to experimental measurements at LEP, Tevatron and LHC, as well as to predictions obtained using PYTHIA. (orig.)

  8. 26 CFR 1.661(a)-1 - Estates and trusts accumulating income or distributing corpus; general.

    Science.gov (United States)

    2010-04-01

    ... distributing corpus; general. 1.661(a)-1 Section 1.661(a)-1 Internal Revenue INTERNAL REVENUE SERVICE... Accumulate Income Or Which Distribute Corpus § 1.661(a)-1 Estates and trusts accumulating income or distributing corpus; general. Subpart C, part I, subchapter J, chapter 1 of the Code, is applicable to...

  9. 46 CFR 113.25-8 - Distribution of general emergency alarm system feeders and branch circuits.

    Science.gov (United States)

    2010-10-01

    ... Systems § 113.25-8 Distribution of general emergency alarm system feeders and branch circuits. (a) Each... alarm signal. (e) Each system must have one or more branch circuit distribution panels for each zone... 46 Shipping 4 2010-10-01 2010-10-01 false Distribution of general emergency alarm system...

  10. Parton Model from Bi-local Solitonic Picture of the Baryon in two-dimensions

    CERN Document Server

    John, V; Rajeev, S G

    2000-01-01

    We study a previously introduced bi-local gauge invariant reformulation of two dimensional QCD, called 2d HadronDynamics. The baryon arises as a topological soliton in HadronDynamics. We derive an interacting parton model from the soliton model, thus reconciling these two seemingly different points of view. The valence quark model is obtained as a variational approximation to HadronDynamics. A succession of better approximations to the soliton picture are obtained. The next simplest case corresponds to a system of interacting valence, `sea' and anti-quarks. We also obtain this `embellished' parton model directly from the valence quark system through a unitary transformation. Using the solitonic point of view, we estimate the quark and anti-quark distributions of 2d QCD. Possible applications to Deep Inelastic Structure Functions are pointed out.

  11. Real-time description of parton-hadron conversion and confinement dynamics

    CERN Document Server

    Ellis, Jonathan Richard; Ellis, John; Geiger, Klaus

    1995-01-01

    We propose a new and universal approach to the hadronization problem that incorporates both partonic and hadronic degrees of freedom in their respective domains of relevance, and that describes the conversion between them within a kinetic field theory formulation in real time and full 7-dimensional phase space. We construct a scale-dependent effective theory that reduces to perturbative QCD with its scale and chiral symmetry properties at short space-time distances, but at large distances (r > 1 fm) yields symmetry breaking gluon and quark condensates plus hadronic excitations. The approach is applied to the evolution of fragmenting qq~ and gg jet pairs as the system evolves from the initial 2-jet configuration, via parton showering and cluster formation, to the final yield of hadrons. The phenomenological implications for e+e- -> hadrons are investigated, such as the time scale of the transition, and its energy dependence, cluster size and mass distributions. We compare our results for particle production an...

  12. Double parton scattering in pair-production of $J/\\psi$ mesons at the LHC revisited

    CERN Document Server

    Borschensky, Christoph

    2016-01-01

    Double parton scattering (DPS) is studied at the example of $J/\\psi$ pair-production in the LHCb and ATLAS experiments of the Large Hadron Collider (LHC) at centre-of-mass energies of $\\sqrt{S}=$ 7, 8, and 13 TeV. We report theoretical predictions delivered to the LHCb and ATLAS collaborations adjusted for the fiducial volumes of the corresponding measurements during Run I and provide new predictions at 13 TeV collision energy. It is shown that DPS can lead to noticeable contributions in the distributions of longitudinal variables of the di-$J/\\psi$ system, especially at 13 TeV. The increased DPS rate in double $J/\\psi$ production at high energies will open up more possibilities for the separation of single parton scattering (SPS) and DPS contributions in future studies.

  13. Accessing the quark orbital angular momentum with Wigner distributions

    CERN Document Server

    Cedric, Lorce

    2012-01-01

    The quark orbital angular momentum (OAM) has been recognized as an important piece of the proton spin puzzle. A lot of effort has been invested in trying to extract it quantitatively from the generalized parton distributions (GPDs) and the transverse-momentum dependent parton distributions (TMDs), which are accessed in high-energy processes and provide three-dimensional pictures of the nucleon. Recently, we have shown that it is more natural to access the quark OAM from the phase-space or Wigner distributions. We discuss the concept of Wigner distributions in the context of quantum field theory and show how they are related to the GPDs and the TMDs. We summarize the different definitions discussed in the literature for the quark OAM and show how they can in principle be extracted from the Wigner distributions.

  14. Dijet Cross Sections and Parton Densities in Diffractive DIS at HERA

    CERN Document Server

    Aktas, A.; Andreev, V.; Anthonis, T.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R.C.W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martisikova, M.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Polifka, R.; Povh, B.; Preda, T.; Prideaux, P.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Sloan, T.; Smiljanic, Ivan; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Staykova, Z.; Steder, M.; Stella, B.; Stiewe, J.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Utkin, D.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2007-01-01

    Differential dijet cross sections in diffractive deep-inelastic scattering are measured with the H1 detector at HERA using an integrated luminosity of 51.5 pb-1. The selected events are of the type ep --> eXY, where the system X contains at least two jets and is well separated in rapidity from the low mass proton dissociation system Y. The dijet data are compared with QCD predictions at next-to-leading order based on diffractive parton distribution functions previously extracted from measurements of inclusive diffractive deep-inelastic scattering. The prediction describes the dijet data well at low and intermediate zpom (the fraction of the momentum of the diffractive exchange carried by the parton entering the hard interaction) where the gluon density is well determined from the inclusive diffractive data, supporting QCD factorisation. A new set of diffractive parton distribution functions is obtained through a simultaneous fit to the diffractive inclusive and dijet cross sections. This allows for a precise ...

  15. Dijet Cross Sections and Parton Densities in Diffractive DIS at HERA

    CERN Document Server

    Alexa, C; Anthonis, T; Antunovic, B; Aplin, S; Asmone, A; Astvatsatourov, A; Backovic, S; Baghdasaryan, A; Baranov, P; Barrelet, E; Bartel, Wulfrin; Baudrand, S; Beckingham, M; Begzsuren, K; Behnke, O; Behrendt, O; Belousov, A; Berger, N; Bizot, J C; Boenig, M O; Boudry, V; Bozovic-Jelisavcic, I; Bracinik, J; Brandt, G; Brinkmann, M; Brisson, V; Bruncko, D; Büsser, F W; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Cantun Avila, K B; Cassol-Brunner, F; Cerny, K; Cerny, V; Chekelian, V; Cholewa, A; Contreras, J G; Coughlan, J A; Cozzika, G; Cvach, J; Dainton, J B; Daum, K; Deák, M; De Boer, Y; Delcourt, B; Del Degan, M; Delvax, J; de Roeck, A; De Wolf, E A; Diaconu, C; Dodonov, V; Dubak, A; Eckerlin, G; Efremenko, V; Egli, S; Eichler, R; Eisele, F; Eliseev, A; Elsen, E; Essenov, S; Falkiewicz, A; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Feltesse, J; Ferencei, J; Finke, L; Fleischer, M; Fomenko, A; Franke, G; Frisson, T; Gabathuler, E; Gayler, J; Ghazaryan, S; Ginzburgskaya, S; Glazov, A; Glushkov, I; Görlich, L; Goettlich, M; Gogitidze, N; Gorbounov, S; Gouzevitch, M; Grab, C; Greenshaw, T; Grell, B R; Grindhammer, G; Habib, S; Haidt, D; Hansson, M; Heinzelmann, G; Helebrant, C; Henderson, R C W; Henschel, H; Herrera-Corral, G; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R; Hovhannisyan, A; Hreus, T; Jacquet, M; Janssen, M E; Janssen, X; Jemanov, V; Jönsson, L B; Johnson, D P; Jung, A W; Jung, H; Kapichine, M; Katzy, J; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Klimkovich, T; Kluge, T; Knutsson, A; Korbel, V; Kostka, P; Krämer, M; Krastev, K; Kretzschmar, J; Kropivnitskaya, A; Krüger, K; Landon, M P J; Lange, W; Lastoviicka-Medin, G; Laycock, P; Lebedev, A; Leibenguth, G; Lendermann, V; Levonian, S; Li, G; Lindfeld, L; Lipka, K; Liptaj, A; List, B; List, J; Loktionova, N; López-Fernandez, R; Lubimov, V; Lucaci-Timoce, A I; Lytkin, L; Makankine, A; Malinovskii, E I; Marage, P; Marti, L; Martisikova, M; Martyn, H U; Maxfield, S J; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, H; Meyer, J; Michels, V; Mikocki, S; Milcewicz-Mika, I; Mohamed, A; Moreau, F; Morozov, A; Morris, J V; Mozer, M U; Müller, K; Murn, P; Nankov, K; Naroska, B; Naumann, T; Newman, P R; Niebuhr, C; Nikiforov, A; Nowak, G; Nowak, K; Nozicka, M; Oganezov, R; Olivier, B; Olsson, J E; Osman, S; Ozerov, D; Palichik, V; Panagoulias, I; Pandurovic, M; Papadopoulou, T; Pascaud, C; Patel, G D; Peng, H; Pérez, E; Perez-Astudillo, D; Perieanu, A; Petrukhin, A; Picuric, I; Piec, S; Pitzl, D; Placakyte, R; Polifka, R; Povh, B; Preda, T; Prideaux, P; Radescu, V; Rahmat, A J; Raicevic, N; Ravdandorj, T; Reimer, P; Risler, C; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rurikova, Z; Rusakov, S; Salvaire, F; Sankey, D P C; Sauter, M; Sauvan, E; Schmidt, S; Schmitt, S; Schmitz, C; Schoeffel, L; Schöning, A; Schultz-Coulon, H C; Sefkow, F; Shaw-West, R N; Shevyakov, I; Shtarkov, L N; Sloan, T; Smiljanic, I; Smirnov, P; Soloviev, Yu; South, D; Spaskov, V; Specka, A; Staykova, Z; Steder, M; Stella, B; Stiewe, J; Straumann, U; Sunar, D; Sykora, T; Tchoulakov, V; Thompson, G; Thompson, P D; Toll, T; Tomasz, F; Tran, T H; Traynor, D; Trinh, T N; Truöl, P; Tsakov, I; Tseepeldorj, B; Tsipolitis, G; Tsurin, I; Turnau, J; Tzamariudaki, E; Urban, K; Utkin, D; Valkárová, A; Vallée, C; Van Mechelen, P; Vargas-Trevino, A; Vazdik, Ya; Vinokurova, S; Volchinski, V; Weber, G; Weber, R; Wegener, D; Werner, C; Wessels, M; Wissing, C; Wolf, R; Wünsch, E; Xella, S; Yeganov, V; Zácek, J; Zaleisak, J; Zhang, Z; Zhelezov, A; Zhokin, A; Zhu, Y C; Zimmermann, T; Zohrabyan, H; Zomer, F

    2007-01-01

    Differential dijet cross sections in diffractive deep-inelastic scattering are measured with the H1 detector at HERA using an integrated luminosity of 51.5 pb-1. The selected events are of the type ep --> eXY, where the system X contains at least two jets and is well separated in rapidity from the low mass proton dissociation system Y. The dijet data are compared with QCD predictions at next-to-leading order based on diffractive parton distribution functions previously extracted from measurements of inclusive diffractive deep-inelastic scattering. The prediction describes the dijet data well at low and intermediate zpom (the fraction of the momentum of the diffractive exchange carried by the parton entering the hard interaction) where the gluon density is well determined from the inclusive diffractive data, supporting QCD factorisation. A new set of diffractive parton distribution functions is obtained through a simultaneous fit to the diffractive inclusive and dijet cross sections. This allows for a precise ...

  16. Double parton scattering in the ultraviolet. Addressing the double counting problem

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gaunt, Jonathan R. [Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Amsterdam (Netherlands); Vrije Univ. Amsterdam (Netherlands)

    2016-03-15

    In proton-proton collisions there is a smooth transition between the regime of double parton scattering, initiated by two pairs of partons at a large relative distance, and the regime where a single parton splits into a parton pair in one or both protons. We present a scheme for computing both contributions in a consistent and practicable way.

  17. Bioclimatic distribution of vegetation for general circulation model studies

    Science.gov (United States)

    Prentice, Katharine Culbertson

    1990-01-01

    Four global bioclimatic schemes which qualify climates on the basis of the distribution of vegetation, including the Holdridge (1947), Thornthwaite (1948), Koeppen (1936), and Troll and Paffen (1964) schemes, were applied to two global climate data sets to produce maps of global vegetation distribution: the Rand set described by Schutz and Gates (1971, 1973, and 1974) and the Shea (1986) data set. The results show that only 38 to 40 percent of the observed land surface, mapped as 31 vegetation types, could be replicated by applying the four schemes to these data sets. The simulations were significantly improved by further subdividing and regrouping the climates defined by the schemes and by regrouping the observed vegetation types. With these alterations, 77 percent of the predicted vegetative landscape coresponded with the observed distribution of vegetation.

  18. Parton-Hadron-String Dynamics at Relativistic Collider Energies

    CERN Document Server

    Bratkovskaya, E L; Konchakovski, V P; Linnyk, O

    2011-01-01

    The novel Parton-Hadron-String Dynamics (PHSD) transport approach is applied to nucleus-nucleus collisions at RHIC energies with respect to differential hadronic spectra in comparison to available data. The PHSD approach is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results from the Wuppertal-Budapest group in thermodynamic equilibrium. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark-antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy-momentum conservation. Our dynamical studies for heavy-ion collisions at relativistic collider energies are compared to earlier results from the Hadron-String Dynamics (HSD) approach - incorporating no explicit dynamical partonic phase - as well as to experimental data from the STAR, PHENIX, BRAHMS and PHOBOS collaborations for Au+Au collisions at the top RHIC energy...

  19. Multiple parton interactions in photoproduction at HERA/H1

    Energy Technology Data Exchange (ETDEWEB)

    Magro, Lluis Marti

    2009-02-15

    Photoproduction data of HERA-I are analysed by requiring dijets with transverse momenta of at least 5 GeV. The two jets define in azimuth a towards region (leading jet), an away region (usually the 2nd jet) and transverse regions between them. The charged particle and jet with low transverse momentum multiplicity, so called minijets, are measured in these regions as a function of the variables x{sup obs}{sub {gamma}} and P{sup Jet{sub 1T}} (leading jet). The measurement is compared to predictions including parton showers and matrix elements at leading order in {alpha}{sub s}. Some predictions include contributions from multiple parton interactions and use different parton evolution equations. It was found that existing MC programs do not fully describe the measurements but the description can be improved by including multiple parton interactions. (orig.)

  20. Prediction in Partial Duration Series With Generalized Pareto-Distributed Exceedances

    DEFF Research Database (Denmark)

    Rosbjerg, Dan; Madsen, Henrik; Rasmussen, Peter Funder

    1992-01-01

    As a generalization of the common assumption of exponential distribution of the exceedances in Partial duration series the generalized Pareto distribution has been adopted. Estimators for the parameters are presented using estimation by both method of moments and probability-weighted moments......-weighted moments. Maintaining the generalized Pareto distribution as the parent exceedance distribution the T-year event is estimated assuming the exceedances to be exponentially distributed. For moderately long-tailed exceedance distributions and small to moderate sample sizes it is found, by comparing mean...... square errors of the T-year event estimators, that the exponential distribution is preferable to the correct generalized Pareto distribution despite the introduced model error and despite a possible rejection of the exponential hypothesis by a test of significance. For moderately short-tailed exceedance...

  1. Measurement of the muon charge asymmetry in inclusive $pp \\to W+X$ production at $\\sqrt s$ = 7 TeV and an improved determination of light parton distribution functions

    OpenAIRE

    Chatrchyan, S.; Khachatryan, Vardan; Fruehwirth, Rudolf; Zaganidis, Nicolas; Varela, Joao; Vischia, Pietro; Bunin, Pavel; Golutvin, Igor; Gorbunov, Ilya; Kamenev, Alexey; Karjavin, Vladimir; Konoplyanikov, Viktor; Kozlov, Guennady; Lanev, Alexander; Basegmez, Suzan

    2014-01-01

    Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI. Measurements of the muon charge asymmetry in inclusive pp → W + X production at root s= 7 TeV are presented. The data sample corresponds to an integrated luminosity of 4.7 fb−1 recorded with the CMS detector at the LHC. With a sample of more ...

  2. Reweighting QCD matrix-element and parton-shower calculations

    Science.gov (United States)

    Bothmann, Enrico; Schönherr, Marek; Schumann, Steffen

    2016-11-01

    We present the implementation and validation of the techniques used to efficiently evaluate parametric and perturbative theoretical uncertainties in matrix-element plus parton-shower simulations within the Sherpa event-generator framework. By tracing the full α _s and PDF dependences, including the parton-shower component, as well as the fixed-order scale uncertainties, we compute variational event weights on-the-fly, thereby greatly reducing the computational costs to obtain theoretical-uncertainty estimates.

  3. Reweighting QCD matrix-element and parton-shower calculations

    CERN Document Server

    Bothmann, Enrico; Schumann, Steffen

    2016-01-01

    We present the implementation and validation of the techniques used to efficiently evaluate parametric and perturbative theoretical uncertainties in matrix-element plus parton-shower simulations within the Sherpa event-generator framework. By tracing the full $\\alpha_s$ and PDF dependences, including the parton-shower component, as well as the fixed-order scale uncertainties, we compute variational event weights on-the-fly, thereby greatly reducing the computational costs to obtain theoretical-uncertainty estimates.

  4. Reweighting QCD matrix-element and parton-shower calculations

    Energy Technology Data Exchange (ETDEWEB)

    Bothmann, Enrico; Schumann, Steffen [Universitaet Goettingen, II. Physikalisches Institut, Goettingen (Germany); Schoenherr, Marek [Universitaet Zuerich, Physik-Institut, Zuerich (Switzerland)

    2016-11-15

    We present the implementation and validation of the techniques used to efficiently evaluate parametric and perturbative theoretical uncertainties in matrix-element plus parton-shower simulations within the Sherpa event-generator framework. By tracing the full α{sub s} and PDF dependences, including the parton-shower component, as well as the fixed-order scale uncertainties, we compute variational event weights on-the-fly, thereby greatly reducing the computational costs to obtain theoretical-uncertainty estimates. (orig.)

  5. Color-dressed recursive relations for multi-parton amplitudes

    CERN Document Server

    Duhr, C; Maltoni, F; Duhr, Claude; Hoeche, Stefan; Maltoni, Fabio

    2006-01-01

    Remarkable progress inspired by twistors has lead to very simple analytic expressions and to new recursive relations for multi-parton color-ordered amplitudes. We show how such relations can be extended to include color and present the corresponding color-dressed formulation for the Berends-Giele, BCF and a new kind of CSW recursive relations. A detailed comparison of the numerical efficiency of the different approaches to the calculation of multi-parton cross sections is performed.

  6. Generalized Load Sharing for Homogeneous Networks of Distributed Environment

    Directory of Open Access Journals (Sweden)

    A. Satheesh

    2008-01-01

    Full Text Available We propose a method for job migration policies by considering effective usage of global memory in addition to CPU load sharing in distributed systems. When a node is identified for lacking sufficient memory space to serve jobs, one or more jobs of the node will be migrated to remote nodes with low memory allocations. If the memory space is sufficiently large, the jobs will be scheduled by a CPU-based load sharing policy. Following the principle of sharing both CPU and memory resources, we present several load sharing alternatives. Our objective is to reduce the number of page faults caused by unbalanced memory allocations for jobs among distributed nodes, so that overall performance of a distributed system can be significantly improved. We have conducted trace-driven simulations to compare CPU-based load sharing policies with our policies. We show that our load sharing policies not only improve performance of memory bound jobs, but also maintain the same load sharing quality as the CPU-based policies for CPU-bound jobs. Regarding remote execution and preemptive migration strategies, our experiments indicate that a strategy selection in load sharing is dependent on the amount of memory demand of jobs, remote execution is more effective for memory-bound jobs, and preemptive migration is more effective for CPU-bound jobs. Our CPU-memory-based policy using either high performance or high throughput approach and using the remote execution strategy performs the best for both CPU-bound and memory-bound job in homogeneous networks of distributed environment.

  7. Multiple parton interactions in high-density QCD matter

    CERN Document Server

    Srivastava, D K; Srivastava, Dinesh K.; Geiger, Klaus

    1999-01-01

    Multiple interactions of quarks and gluons in high-energy heavy-ion collisions may give rise to interesting phemomena of color charges propagating in high-density QCD matter. We study the dynamics of multi-parton systems produced in nucleus-nucleus collisions at energies corresponding the the CERN SPS and the future BNL RHIC experiments. Due to the complexity of the multi-particle dynamics we choose to employ the parton cascade model in order to simulate the development of multiple parton scatterings and associated stimulated emision processes. Our results indicate a non-linear increase with nuclear mass A of, e.g., parton multiplicity, energy density, strangeness, and contrast a linear A-scaling as in Glauber-type approaches. If multiple interactions are suppressed and only single parton scatterings (no re-interactions) are considered, we recover such a linear behavior. It remains to be studied whether these results on the parton level can be experimentally seen in final-state observables, such as the charge...

  8. Parton densities from LHC vector boson production at small and large transverse momenta

    Science.gov (United States)

    Klasen, Michael; Brandt, Matthias

    2013-09-01

    The parton densities of the proton are of fundamental importance not only for our description of hadronic and nuclear structure, but also for reliable predictions for new heavy-particle searches at colliders. At the large partonic momentum fractions required for the production of these particles, the parton distribution functions—in particular, that of the gluon—are unfortunately still badly constrained. In this paper, we investigate the possibility to improve on their determination with new data coming from electroweak vector boson production at large transverse momenta at the LHC with center-of-mass energies of 7, 8, or 14 TeV. We demonstrate that this process is dominated by quark-gluon scattering, that theoretical predictions can be reliably made on the basis of next-to-leading order perturbation theory and its resummation, and that these data should thus be used in global fits. We also point out that the nonperturbative parameters determined from Tevatron Run 1 Z-boson data at low pT describe very well the new LHC data at s=7TeV.

  9. Parton densities from LHC vector boson production at small and large transverse momenta

    CERN Document Server

    Brandt, M

    2013-01-01

    The parton densities of the proton are of fundamental importance not only for our description of hadronic and nuclear structure, but also for reliable predictions for new heavy particle searches at colliders. At the large partonic momentum fractions required for the production of these particles, the parton distribution functions, in particular the one of the gluon, are unfortunately still badly constrained. In this paper, we investigate the possibility to improve on their determination with new data coming from electroweak vector boson production at large transverse momenta at the LHC with center-of-mass energies of 7, 8 or 14 TeV. We demonstrate that this process is dominated by quark-gluon scattering, that theoretical predictions can be reliably made on the basis of next-to-leading order perturbation theory and its resummation, and that these data should thus be used in global fits. We also point out that the non-perturbative parameters determined from Tevatron run-1 Z-boson data at low p_T describe very w...

  10. Generalized binomial multiplicative cascade processes and asymmetrical multifractal distributions

    Science.gov (United States)

    Cheng, Q.

    2014-04-01

    The concepts and models of multifractals have been employed in various fields in the geosciences to characterize singular fields caused by nonlinear geoprocesses. Several indices involved in multifractal models, i.e., asymmetry, multifractality, and range of singularity, are commonly used to characterize nonlinear properties of multifractal fields. An understanding of how these indices are related to the processes involved in the generation of multifractal fields is essential for multifractal modeling. In this paper, a five-parameter binomial multiplicative cascade model is proposed based on the anisotropic partition processes. Each partition divides the unit set (1-D length or 2-D area) into h equal subsets (segments or subareas) and m1 of them receive d1 (> 0) and m2 receive d2 (> 0) proportion of the mass in the previous subset, respectively, where m1+m2 ≤ h. The model is demonstrated via several examples published in the literature with asymmetrical fractal dimension spectra. This model demonstrates the various properties of asymmetrical multifractal distributions and multifractal indices with explicit functions, thus providing insight into and an understanding of the properties of asymmetrical binomial multifractal distributions.

  11. Studies of the underlying-event properties and of hard double parton scattering with the ATLAS detector

    CERN Document Server

    Kuprash, Oleg; The ATLAS collaboration

    2017-01-01

    A correct modelling of the underlying event in proton-proton collisions at Large Hadron Collider is important for the proper simulation of kinematic distributions of final state objects. The ATLAS collaboration performed a study at 13~TeV, measuring the number and transverse-momentum sum of charged particles in different regions with respect to the direction of the reconstructed leading track. These measurements are sensitive to the underlying-event activity. The results are compared to predictions of several Monte Carlo generators. Inclusive four-jet events produced in proton-proton collisions at a centre-of-mass energy of 7~TeV in the ATLAS detector have been analysed for the presence of hard double parton scattering. The fraction of events originating from hard double parton scattering has been extracted, and used to measure the effective proton cross section. Distributions sensitive to the presence of double parton scattering were unfolded to the parton level and compared to various tunes of a selected Mo...

  12. Systematics of parton fragmentation in $e^+$-$e^-$ and nuclear collisions

    CERN Document Server

    Trainor, Thomas A

    2009-01-01

    Parametrizations of fragmentation functions (FFs) from $e^+$-$e^-$ and p-\\=p collisions are combined with a parton spectrum model in a pQCD folding integral to produce minimum-bias {\\em fragment distributions}. A model of in-medium FF modification is included. Calculated fragment distributions are compared with {\\em hard components} from p-p and Au-Au $p_t$ spectra. Data are well described by pQCD over a large kinematic region for a range of Au-Au centralities.

  13. Testing the parton evolution with the use of two-body final states

    CERN Document Server

    Baranov, S P; Lipatov, A V; Malyshev, M A

    2016-01-01

    We consider the production of $b\\bar b$ quarks and Drell-Yan lepton pairs at LHC conditions focusing attention on the total transverse momentum of the produced pair and on the azimuthal angle between the momenta of the outgoing particles. Plotting the corresponding distributions in bins of the final state invariant mass, one can reconstruct the full map of the transverse momentum dependent parton densities in a proton. We give examples of how can these distributions can look like at the LHC energies.

  14. The distribution of zeros of general q-polynomials

    Science.gov (United States)

    Álvarez-Nodarse, R.; Buendía, E.; Dehesa, J. S.

    1997-10-01

    A general system of q-orthogonal polynomials is defined by means of its three-term recurrence relation. This system encompasses many of the known families of q-polynomials, among them the q-analogue of the classical orthogonal polynomials. The asymptotic density of zeros of the system is shown to be a simple and compact expression of the parameters which characterize the asymptotic behaviour of the coefficients of the recurrence relation. This result is applied to specific classes of polynomials known by the names q-Hahn, q-Kravchuk, q-Racah, q-Askey and Wilson, Al Salam - Carlitz and the celebrated little and big q-Jacobi.

  15. Light field distribution of general function photonic crystals

    CERN Document Server

    Wu, Xiang-Yao; Liu, Xiao-Jing; Zhang, Si-Qi; Wang, Jing; Ba, Nuo; Xiao, Li; Li, Hong

    2012-01-01

    In this paper, We have presented a new general function photonic crystals (GFPCs), which refractive indexes are line functions of space position in two mediums $A$ and $B$, and obtain new results: (1) when the line function of refractive indexes is up or down, the transmissivity can be far larger or smaller than 1. (2) when the refractive indexes function increase or decrease along the direction of incident light, the light intensity should be magnified or weaken, which can be made optical magnifier or attenuator. (3) The GFPCs can be made optical diode when the light positive and negative incident the GFPCs.

  16. General Course of Failure Distributions at Complex Machineries

    Directory of Open Access Journals (Sweden)

    Naqib Daneshjo

    2017-02-01

    Full Text Available In the process of maintenance management of machinery and devices there is necessity to keep in the mind "construction technologicity” (ability of construction technology. This term is used in evaluating of machinery construction, their groups and components in terms of production. The aim of management and planning maintenance of machinery is the failure-free operation in the application process. The range of machinery maintenance machines from routine one and inspection to general repairs is important to organize in a way to prevent unplanned idle time and failures or very likely to accidents.

  17. Parton/hadron dynamics in heavy-ion collisions at FAIR energies

    Directory of Open Access Journals (Sweden)

    Cassing W.

    2015-01-01

    Full Text Available Recent STAR data for the directed flow of protons, antiprotons and charged pions obtained within the beam energy scan program are analyzed within the Parton-Hadron-String-Dynamics (PHSD/HSD transport models. Both versions of the kinetic approach are used to clarify the role of partonic degrees of freedom. The PHSD results, simulating a partonic phase and its coexistence with a hadronic one, are roughly consistent with the STAR data. Generally, the semi-qualitative agreement between the measured data and model results supports the idea of a crossover type of quark-hadron transition which softens the nuclear EoS but shows no indication of a first-order phase transition. Furthermore, the directed flow of kaons and antikaons is evaluated in the PHSD/HSD approachesfrom √sNN ≈ 3 - 200 GeV which shows a high sensitivity to hadronic potentials in the FAIR/NICA energy regime √sNN ≤ 8 GeV.

  18. Parton/hadron dynamics in heavy-ion collisions at FAIR energies

    CERN Document Server

    Cassing, W; Palmese, A; Toneev, V D; Bratkovskaya, E L

    2014-01-01

    Recent STAR data for the directed flow of protons, antiprotons and charged pions obtained within the beam energy scan program are analyzed within the Parton-Hadron-String-Dynamics (PHSD/HSD) transport models. Both versions of the kinetic approach are used to clarify the role of partonic degrees of freedom. The PHSD results, simulating a partonic phase and its coexistence with a hadronic one, are roughly consistent with the STAR data. Generally, the semi-qualitative agreement between the measured data and model results supports the idea of a crossover type of quark-hadron transition which softens the nuclear EoS but shows no indication of a first-order phase transition. Furthermore, the directed flow of kaons and antikaons is evaluated in the PHSD/HSD approachesfrom $\\sqrt{s_{NN}} \\approx$ 3 - 200 GeV which shows a high sensitivity to hadronic potentials in the FAIR/NICA energy regime $\\sqrt{s_{NN}} \\le$ 8 GeV.

  19. Distributed GIS oriented generalized image pyramid and its practice

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Gaussian pyramid framework (GPF) and Laplacian pyramid framework (LPF) are the two main frameworks used for transmission and structure of spatial image and geometric data.LPF is the main approach for progressive transmission of spatial image data.This paper discusses the issues in structure,transmission and storage efficiency of spatial data in the current spatially distributed visualization system.Later in the paper a novel approach is introduced to structure and store spatial data based on the LPF.This new approach builds (spatial) index for transformed frequency data within different ranges based on splitting high-frequency and low-frequency data by biorthogonal transformation.This approach decreases the storage consumption and network data traffic for transmission while enables the progressive transmission of spatial image.

  20. Ultrawide Bandwidth Receiver Based on a Multivariate Generalized Gaussian Distribution

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2015-04-01

    Multivariate generalized Gaussian density (MGGD) is used to approximate the multiple access interference (MAI) and additive white Gaussian noise in pulse-based ultrawide bandwidth (UWB) system. The MGGD probability density function (pdf) is shown to be a better approximation of a UWB system as compared to multivariate Gaussian, multivariate Laplacian and multivariate Gaussian-Laplacian mixture (GLM). The similarity between the simulated and the approximated pdf is measured with the help of modified Kullback-Leibler distance (KLD). It is also shown that MGGD has the smallest KLD as compared to Gaussian, Laplacian and GLM densities. A receiver based on the principles of minimum bit error rate is designed for the MGGD pdf. As the requirement is stringent, the adaptive implementation of the receiver is also carried out in this paper. Training sequence of the desired user is the only requirement when implementing the detector adaptively. © 2002-2012 IEEE.

  1. Transition state theory: a generalization to nonequilibrium systems with power-law distributions

    CERN Document Server

    Jiulin, Du

    2011-01-01

    Transition state theory (TST) is generalized for the nonequilibrium system with power-law distributions. The stochastic dynamics that gives rise to the power-law distributions for the reaction coordinate and momentum is modeled by the Langevin equations and corresponding Fokker-Planck equations. It is assumed that the system far away from equilibrium has not to relax to a thermal equilibrium state with Boltzmann-Gibbs distribution, but asymptotically approaches to a nonequilibrium stationary-state with power-law distributions. Thus, we obtain a generalization of TST rates to nonequilibrium systems with power-law distributions. Furthermore, we derive the generalized TST rate constants for one-dimension and n-dimension Hamiltonian systems away from equilibrium, and receive a generalized Arrhenius rate for the system with power-law distributions.

  2. Explicit expressions of the Pietra index for the generalized function for the size distribution of income

    Science.gov (United States)

    Sarabia, José María; Jordá, Vanesa

    2014-12-01

    The importance of the Pietra index in socioeconomic systems and econophysics has been highlighted by Eliazar and Sokolov (2010). In this paper, we obtain closed expressions for the Pietra index for the generalized function for the size of income proposed by McDonald (1984). This family is composed of three classes of distributions: the generalized gamma distribution (GG), the generalized beta of the first kind (GB1) and the generalized beta of the second kind (GB2). For the different distributions, we obtain closed and simple expressions of the Pietra index, which can be easily computed. We also obtain the Pietra index for other relevant income models including finite mixtures of distributions and the κ-generalized distribution (Clementi et al., 2008). Finally, two empirical applications with real income data are given.

  3. A generalized AZ-non-Maxwellian velocity distribution function for space plasmas

    Science.gov (United States)

    Abid, A. A.; Khan, M. Z.; Lu, Quanming; Yap, S. L.

    2017-03-01

    A more generalized form of the non-Maxwellian distribution function, i.e., the AZ-distribution function is presented. Its fundamental properties are numerically observed by the variation of three parameters: α (rate of energetic particles on the shoulder), r (energetic particles on a broad shoulder), and q (superthermality on the tail of the velocity distribution curve of the plasma species). It has been observed that (i) the A Z - distribution function reduces to the ( r , q ) - distribution for α → 0 ; (ii) the A Z - distribution function reduces to the q - distribution for α → 0 , and r → 0 ; (iii) the A Z -distribution reduces to Cairns-distribution function for r → 0 , and q → ∞ ; (iv) the AZ-distribution reduces to Vasyliunas Cairns distribution for r → 0 , and q = κ + 1 ; (v) the AZ-distribution reduces to kappa distribution for α → 0 , r → 0 , and q = κ + 1 ; and (vi) finally, the AZ-distribution reduces to Maxwellian distribution for α → 0 , r → 0 , and q → ∞ . The uses of this more generalized A Z - distribution function in various space plasmas are briefly discussed.

  4. Spectra of produced particles at CERN SPS heavy-ion collisions from a parton-cascade model

    CERN Document Server

    Srivastava, D K; Srivastava, Dinesh Kumar; Geiger, Klaus

    1998-01-01

    We evaluate the spectra of produced particles (pions, kaons, antiprotons) from partonic cascades which may develop in the wake of heavy-ion collisions at CERN SPS energies and which may hadronize by formation of clusters which decay into hadrons. Using the experimental data obtained by NA35 and NA44 collaborations for S+S and Pb+Pb collisions, we conclude that the Monte Carlo implementation of the recently developed parton-cascade/cluster-hadronization model provides a reasonable description of the distributions of the particles produced in such collisions. While the rapidity distribution of the mid-rapidity protons is described reasonably well, their transverse momentum distribution falls too rapidly compared to the experimental values, implying a significant effect of final state scattering among the produced hadrons neglected so far.

  5. VBFNLO: A parton level Monte Carlo for processes with electroweak bosons

    Science.gov (United States)

    Arnold, K.; Bähr, M.; Bozzi, G.; Campanario, F.; Englert, C.; Figy, T.; Greiner, N.; Hackstein, C.; Hankele, V.; Jäger, B.; Klämke, G.; Kubocz, M.; Oleari, C.; Plätzer, S.; Prestel, S.; Worek, M.; Zeppenfeld, D.

    2009-09-01

    VBFNLO is a fully flexible parton level Monte Carlo program for the simulation of vector boson fusion, double and triple vector boson production in hadronic collisions at next-to-leading order in the strong coupling constant. VBFNLO includes Higgs and vector boson decays with full spin correlations and all off-shell effects. In addition, VBFNLO implements CP-even and CP-odd Higgs boson via gluon fusion, associated with two jets, at the leading-order one-loop level with the full top- and bottom-quark mass dependence in a generic two-Higgs-doublet model. A variety of effects arising from beyond the Standard Model physics are implemented for selected processes. This includes anomalous couplings of Higgs and vector bosons and a Warped Higgsless extra dimension model. The program offers the possibility to generate Les Houches Accord event files for all processes available at leading order. Program summaryProgram title:VBFNLO Catalogue identifier: AEDO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL version 2 No. of lines in distributed program, including test data, etc.: 339 218 No. of bytes in distributed program, including test data, etc.: 2 620 847 Distribution format: tar.gz Programming language: Fortran, parts in C++ Computer: All Operating system: Linux, should also work on other systems Classification: 11.1, 11.2 External routines: Optionally Les Houches Accord PDF Interface library and the GNU Scientific library Nature of problem: To resolve the large scale dependence inherent in leading order calculations and to quantify the cross section error induced by uncertainties in the determination of parton distribution functions, it is necessary to include NLO corrections. Moreover, whenever stringent cuts are required on decay products and/or identified jets the question arises whether the scale dependence and a k-factor, defined

  6. Intrinsic parton motion and the longitudinal spin asymmetry A_LL in high energy pp -> pi X

    CERN Document Server

    Anselmino, M; D'Alesio, U; Leader, E; Melis, S; Murgia, F

    2007-01-01

    The longitudinal double spin asymmetry A_LL in the reaction pp -> pi X has been measured at RHIC with extremely interesting consequences. If the gluon polarization in a proton were as big as needed to resolve the famous "spin crisis" then A_LL would be large and positive. Early RHIC results suggested that A_LL might even be negative, which is impossible in the simple collinear parton model. Later results indicate very small positive values. Recently, for the first time, we derived expressions for the general partonic structure for all hadron spin asymmetries with inclusion of all transverse motion of the partons in a hadron and of the hadrons in a fragmenting parton. Besides the standard soft functions that are present in the collinear treatment, several new spin and k_T dependent soft functions appear and contribute to the cross sections and to spin asymmetries, both transverse and longitudinal. We examine the influence of k_T and of the new terms on A_LL, and in particular whether they could alter the concl...

  7. Towards a consistent description of in-medium parton branching

    CERN Document Server

    Apolinário, Liliana; Milhano, Guilherme; Salgado, Carlos A

    2015-01-01

    Ultra-relativistic heavy-ion collisions are a window of opportunity to study QCD matter under extreme conditions of temperature and density, such as the quark-gluon plasma. Among the several possibilities, the study of jet quenching - generic name given to in-medium energy loss modifications of the parton branching - is a powerful tool to assess the properties of this new state of matter. The description of the parton shower is very well understood in vacuum (controlled reference) and medium-induced modifications of this process can be experimentally accessed through jet measurements. Current experimental data, however, cannot be entirely described only with energy loss phenomena. Transverse momentum broadening and decoherence effects, both theoretically established by now, and their interplay are essential to build a consistent picture of the medium-modifications of the parton branching and to achieve a correct description of the current experimental data. In this write-up, we will present the latest develop...

  8. Polarized 3 parton production in inclusive DIS at small x

    Science.gov (United States)

    Ayala, Alejandro; Hentschinski, Martin; Jalilian-Marian, Jamal; Tejeda-Yeomans, Maria Elena

    2016-10-01

    Azimuthal angular correlations between produced hadrons/jets in high energy collisions are a sensitive probe of the dynamics of QCD at small x. Here we derive the triple differential cross section for inclusive production of 3 polarized partons in DIS at small x. The target proton or nucleus is described using the Color Glass Condensate (CGC) formalism. The resulting expressions are used to study azimuthal angular correlations between produced partons in order to probe the gluon structure of the target hadron or nucleus. Our analytic expressions can also be used to calculate the real part of the Next to Leading Order (NLO) corrections to di-hadron production in DIS by integrating out one of the three final state partons.

  9. Polarized 3 parton production in inclusive DIS at small x

    CERN Document Server

    Ayala, A; Jalilian-Marian, J; Tejeda-Yeomans, M E

    2016-01-01

    Azimuthal angular correlations between produced hadrons/jets in high energy collisions are a sensitive probe of the dynamics of QCD at small x. Here we derive the triple differential cross section for inclusive production of 3 polarized partons in DIS at small x using the spinor helicity formalism. The target proton or nucleus is described using the Color Glass Condensate (CGC) formalism. The resulting expressions are used to study azimuthal angular correlations between produced partons in order to probe the gluon structure of the target hadron or nucleus. Our analytic expressions can also be used to calculate the real part of the Next to Leading Order (NLO) corrections to di-hadron production in DIS by integrating out one of the three final state partons.

  10. A Generalized Model for Electrical Power Distribution Feeders’ Contributions to System Reliability Indices

    Directory of Open Access Journals (Sweden)

    Ganiyu A. Ajenikoko

    2014-01-01

    Full Text Available Reliability indices are parametric quantities used to assess the performance levels of electrical power distribution systems. In this work, a generalized quadratic model is developed for electrical power distribution system contributions to system reliability indices using Ikeja, Port-Harcourt, Kaduna and Kano distribution system feeders as case studies. The mean System Average Interruption Duration Index (SAIDI, System Average Interruption Frequency Index (SAIFI and Customer Average Interruption Duration Index (CAIDI contributions to system reliability indices for Ikeja, Port-Harcourt, Kaduna and Kano distribution systems were 0.0033, 0.0026, 0.0033 and 0.0018 respectively due to the fact that a prolonged period of interruptions was recorded on most of the feeders attached to Port-Harcourt and Kano distribution systems making them to be less reliable compared to Ikeja and Kaduna distribution systems. The generalized Quadratic model forms a basis for a good design, planning and maintenance of distribution systems at large.

  11. On the concept of local parton-hadron duality

    Energy Technology Data Exchange (ETDEWEB)

    Dokshitzer, Yu.L.; Khoze, V.A.; Troyan, S.I. (Lund Univ. (Sweden). Dept. of Theoretical Physics AN SSSR, Leningrad (USSR). Inst. Yadernoj Fiziki)

    1991-10-01

    In the last decade jet physics has been intensively studied at both e{sup +}e{sup -} and hadronic colliders. With the start of LEP activity a wealth of new data has become available. They show that the global features of hadronic jets systems (multiplicities, angular patterns of particle flows, inclusive energy spectra etc), calculated at the parton level, agree very well with the measured ones. This convincingly demonstrates the dominant role of the perturbative phase of jet evolution and strongly supports the hypothesis of local parton-hadron duality. (author).

  12. Controlling inclusive cross sections in parton shower + matrix element merging

    Energy Technology Data Exchange (ETDEWEB)

    Plaetzer, Simon

    2012-11-15

    We propose an extension of matrix element plus parton shower merging at tree level to preserve inclusive cross sections obtained from the merged and showered sample. Implementing this constraint generates approximate next-to-leading order (NLO) contributions similar to the LoopSim approach. We then show how full NLO, or in principle even higher order, corrections can be added consistently, including constraints on inclusive cross sections to account for yet missing parton shower accuracy at higher logarithmic order. We also show how NLO accuracy below the merging scale can be obtained.

  13. Some Computational and Theoretical Aspects of the Exponentiated Generalized Nadarajah-Haghighi Distribution

    OpenAIRE

    VedoVatto, T.; Nascimento, A. D. C.; Filho, W. R. Miranda; Lima, M. C. S.; Pinho, L. G. B.; Cordeiro, G. M.

    2016-01-01

    Real data from applications in the survival context have required the use of more flexible models. A new four-parameter model called the Exponentiated Generalized Nadarajah-Haghighi (EGNH) distribution has been introduced in order to verify this requirement.

  14. Generalized Shape and Gauge Decoupling Load Distribution Optimization Based on IGA for Tandem Cold Mill

    Institute of Scientific and Technical Information of China (English)

    PENG Peng; YANG Quan

    2009-01-01

    Load distribution is the foundation of shape control and gauge control, in which it is necessary to take into account the shape control ability of TCM (tandem cold mill) for strip shape and gauge quality. First, the objective function of generalized shape and gauge decoupling load distribution optimization was established, which considered the rolling force characteristics of the first and last stands in TCM, the relative power, and the TCM shape control ability. Then, IGA (immune genetic algorithm) was used to accomplish this multi-objective load distribution optimization for TCM. After simulation and comparison with the practical load distribution strategy in one tandem cold mill, general-ized shape and gauge decoupling load distribution optimization on the basis of IGA approved good ability of optimizing shape control and gauge control simultaneously.

  15. Ultrasonic backscattering in tissue: characterization through Nakagami-generalized inverse Gaussian distribution.

    Science.gov (United States)

    Agrawal, Rajeev; Karmeshu

    2007-02-01

    Ultrasonic tissue characterization through composite probability distributions such as Nakagami-lognormal, Nakagami-gamma, Nakagami-inverse Gaussian has been found to be useful. Such a probabilistic description also depicts heavy tails which arise from multiple scattering in tissue besides local and global variations in scattering cross-sections. A new composite probability distribution, viz. Nakagami-generalized inverse Gaussian distribution (NGIGD) with four parameters is proposed which under different limiting conditions results in approximating the known distributions. A salient aspect of the new distribution is that the probability density function (pdf) of NGIGD variate is available in closed form and is analytically tractable.

  16. A Sequence of Escort Distributions and Generalizations of Expectations on q-Exponential Family

    Directory of Open Access Journals (Sweden)

    Hiroshi Matsuzoe

    2016-12-01

    Full Text Available In the theory of complex systems, long tailed probability distributions are often discussed. For such a probability distribution, a deformed expectation with respect to an escort distribution is more useful than the standard expectation. In this paper, by generalizing such escort distributions, a sequence of escort distributions is introduced. As a consequence, it is shown that deformed expectations with respect to sequential escort distributions effectively work for anomalous statistics. In particular, it is shown that a Fisher metric on a q-exponential family can be obtained from the escort expectation with respect to the second escort distribution, and a cubic form (or an Amari–Chentsov tensor field, equivalently is obtained from the escort expectation with respect to the third escort distribution.

  17. A general purpose subroutine for fast fourier transform on a distributed memory parallel machine

    Science.gov (United States)

    Dubey, A.; Zubair, M.; Grosch, C. E.

    1992-01-01

    One issue which is central in developing a general purpose Fast Fourier Transform (FFT) subroutine on a distributed memory parallel machine is the data distribution. It is possible that different users would like to use the FFT routine with different data distributions. Thus, there is a need to design FFT schemes on distributed memory parallel machines which can support a variety of data distributions. An FFT implementation on a distributed memory parallel machine which works for a number of data distributions commonly encountered in scientific applications is presented. The problem of rearranging the data after computing the FFT is also addressed. The performance of the implementation on a distributed memory parallel machine Intel iPSC/860 is evaluated.

  18. On relativistically invariant method of constructing one- and two-parton density matrix

    CERN Document Server

    Shchelkachev, A V

    2001-01-01

    Hadron is considered as a system of one or two partons and a nucleus that contains many partons, but is described as a parton with variable mass. By integration over this mass the relativistically invariant density matrix is constructed. Using this method one can obtained simple relationships between the density matrix elements and to check or give a better interpretation of the hypotheses proposed by the parton models of various authors

  19. Generalization of the logistic distribution in the dynamic model of wind direction

    Science.gov (United States)

    Kaplya, E. V.

    2016-12-01

    Statistical regularity in the dynamics of wind direction has been found. The density distribution of the increment of the wind-direction angle has been approximated using a generalized advanced logistic distribution. The advanced logistic distribution involves an additional power-law parameter. The parameters of the approximation function have been computed from experimental data using the method of least squares. The consistency of the proposed function with meteorological data has been tested using Pearson's chisquared test and the Kolmogorov test.

  20. Inequitable distribution of general practitioners in Australia: estimating need through the Robin Hood Index.

    Science.gov (United States)

    Wilkinson, D; Symon, B

    2000-02-01

    From Census data, to document the distribution of general practitioners in Australia and to estimate the number of general practitioners needed to achieve an equitable distribution accounting for community health need. Data on location of general practitioners, population size and crude mortality by statistical division (SD) were obtained from the Australian Bureau of Statistics. The number of patients per general practitioner by SD was calculated and plotted. Using crude mortality to estimate community health need, a ratio of the number of general practitioners per person: mortality was calculated for all Australia and for each SD (the Robin Hood Index). From this, the number of general practitioners needed to achieve equity was calculated. In all, 26,290 general practitioners were identified in 57 SDs. The mean number of people per general practitioner is 707, ranging from 551 to 1887. Capital city SDs have most favourable ratios. The Robin Hood Index for Australia is 1, and ranges from 0.32 (relatively under-served) to 2.46 (relatively over-served). Twelve SDs (21%) including all capital cities and 65% of all Australians, have a Robin Hood Index > 1. To achieve equity per capita 2489 more general practitioners (10% of the current workforce) are needed. To achieve equity by the Robin Hood Index 3351 (13% of the current workforce) are needed. The distribution of general practitioners in Australia is skewed. Nonmetropolitan areas are relatively underserved. Census data and the Robin Hood Index could provide a simple means of identifying areas of need in Australia.

  1. Q2-evolution of parton densities at small x values

    CERN Document Server

    Kotikov, A V

    2016-01-01

    The Bessel-inspired behavior of parton densities at small x, obtained in the case of the flat initial conditions for DGLAP evolution equations, is used in the fixed flavor scheme to analyze precise H1+ZEUS combined data on the structure function F2.

  2. Underlying Event and Double Parton Scattering Measurements at CMS

    CERN Document Server

    Gupta, Rajat

    2017-01-01

    Recent results on the double parton scattering studies and measurement of the underlying event activity, performed using proton-proton collisions data collected using the CMS detector are presented. Comparisons to previous results at different center of mass energies are also reported.

  3. Studies of double parton scattering in ATLAS arXiv

    CERN Document Server

    Lobodzinska, E.M.

    In this contribution, Double Parton Scattering processes observed with the ATLAS detector at LHC are discussed. Results of five analyses are presented: production of W boson in association with 2 jets, production of J/psi meson in association with W boson, J/psi production with Z boson, J/psi pair production and four jet events.

  4. In-Medium Parton Branching Beyond Eikonal Approximation

    Science.gov (United States)

    Apolinário, Liliana

    2017-03-01

    The description of the in-medium modifications of partonic showers has been at the forefront of current theoretical and experimental efforts in heavy-ion collisions. It provides a unique laboratory to extend our knowledge frontier of the theory of the strong interactions, and to assess the properties of the hot and dense medium (QGP) that is produced in ultra-relativistic heavy-ion collisions at RHIC and the LHC. The theory of jet quenching, a commonly used alias for the modifications of the parton branching resulting from the interactions with the QGP, has been significantly developed over the last years. Within a weak coupling approach, several elementary processes that build up the parton shower evolution, such as single gluon emissions, interference effects between successive emissions and corrections to radiative energy loss of massive quarks, have been addressed both at eikonal accuracy and beyond by taking into account the Brownian motion that high-energy particles experience when traversing a hot and dense medium. In this work, by using the setup of single gluon emission from a color correlated quark-antiquark pair in a singlet state (qbar{q} antenna), we calculate the in-medium gluon radiation spectrum beyond the eikonal approximation. The results show that we are able to factorize broadening effects from the modifications of the radiation process itself. This constitutes the final proof that a probabilistic picture of the parton shower evolution holds even in the presence of a QGP.

  5. Reliability analysis of extended generalized inverted expo-nential distribution with applications

    Institute of Scientific and Technical Information of China (English)

    Arwa M.Alshangiti; M.Kayid; M. Almulhim

    2016-01-01

    A general version of the inverted exponential distri-bution is introduced, studied and analyzed. This generaliza-tion depends on the method of Marshal-Olkin to extend a family of distributions. Some statistical and reliability proper-ties of this family are studied. In addition, numerical estimation of the maximum likelihood estimate (MLE) parameters are discussed in details. As an application, some real data sets are analyzed and it is observed that the presented family provides a better fit than some other known distributions.

  6. Prediction in Partial Duration Series With Generalized Pareto-Distributed Exceedances

    DEFF Research Database (Denmark)

    Rosbjerg, Dan; Madsen, Henrik; Rasmussen, Peter Funder

    1992-01-01

    As a generalization of the common assumption of exponential distribution of the exceedances in Partial duration series the generalized Pareto distribution has been adopted. Estimators for the parameters are presented using estimation by both method of moments and probability-weighted moments....... The corresponding estimators for the T-year event are given and approximate expressions for bias and variance of the estimators are derived in both cases. Using the mean square error of the T-year event estimator as a performance index it is shown that the method of moments is preferable to the probability...... square errors of the T-year event estimators, that the exponential distribution is preferable to the correct generalized Pareto distribution despite the introduced model error and despite a possible rejection of the exponential hypothesis by a test of significance. For moderately short-tailed exceedance...

  7. Jet asymmetry and momentum imbalance from $2 \\to 2$ and $2 \\to 3$ partonic processes in relativistic heavy-ion collisions

    CERN Document Server

    Ayala, Alejandro; Jalilian-Marian, Jamal; Tejeda-Yeomans, Maria Elena

    2015-01-01

    We study momentum imbalance as a function of jet asymmetry in high-energy heavy-ion collisions. To implement parton production during the collision, we include all Leading Order (LO) $2\\to 2$ and $2\\to 3$ parton processes in pQCD. The produced partons lose energy within the quark gluon plasma and hadronize collinearly when they leave it. The energy and momentum deposited into the plasma is described using linear viscous hydrodynamics with a constant energy loss per unit length and a total energy loss given by a Gaussian probability centered around a mean value $\\bar{\\mathcal{E}}$ and a half-width $\\Delta{\\mathcal{E}}$. We argue that the shape of the asymmetry observed by the CERN-CMS Collaboration can indeed be attributed to parton energy loss in the medium and that a good description of data is achieved when one includes a slight enhancement coming from the contribution of $2\\to 3$ parton processes that modifies the asymmetry distribution of the dijet events. We compare our results to CMS data for the most c...

  8. 3D parton imaging of the nucleon in high-energy p p and p A collisions

    CERN Document Server

    Frankfurt, L; Weiss, C

    2004-01-01

    We discuss several examples of how the transverse spatial distribution of partons in the nucleon, as well as multiparton correlations, can be probed by observing hard processes (dijets) in high-energy pp(pp) and pA(dA) collisions. Such studies can complement the information gained from measurements of hard exclusive processes in ep scattering. The transverse spatial distribution of partons determines the distribution over pp impact parameters of events with hard dijet production. Correlations in the transverse positions of partons can be studied in multiple dijet production. We find that the correlation cross section measured by the CDF Collaboration, sigma//e //f//f = 14.5 plus or minus 1.7//-//2//.//3**+**1**.**7 mb, can be explained by "constituent quark" type quark-gluon correlations with r //q approximately equals r//N/3, as suggested by the instanton liquid model of the QCD vacuum. Longitudinal and transverse multiparton correlations can be separated in a model-independent way by comparing multiple dije...

  9. Whistler-Mode Waves Growth by a Generalized Relativistic Kappa-Type Distribution

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qing-Hua; JIANG Bin; SHI Xiang-Hua; LI Jun-Qiu

    2009-01-01

    The instability of field-aligned Whistler-mode waves in space plasmas is studied by using a recently developed generalized relativistic kappa-type (KT) distribution. Numerical calculations are performed for a direct compar-ison between the new KT distribution and the current kappa distribution. We show that the wave growth for the KT distribution tends to occur in the lower wave frequency (e.g., ω 0.1Ωe) due to a larger fractional num-ber of the resonant electrons ηrel (which controls the wave growth), while primarily locating in the higher wave frequency for the kappa distribution. Moreover, the relativistic anisotropy Arel by the KT distribution is found to be smaller than that by the kappa distribution, leading to a smaller peak of wave growth. The results present a further understanding of plasma wave instability particularly in those plasmas where relativistic electrons are present.

  10. A novel generalized normal distribution for human longevity and other negatively skewed data.

    Science.gov (United States)

    Robertson, Henry T; Allison, David B

    2012-01-01

    Negatively skewed data arise occasionally in statistical practice; perhaps the most familiar example is the distribution of human longevity. Although other generalizations of the normal distribution exist, we demonstrate a new alternative that apparently fits human longevity data better. We propose an alternative approach of a normal distribution whose scale parameter is conditioned on attained age. This approach is consistent with previous findings that longevity conditioned on survival to the modal age behaves like a normal distribution. We derive such a distribution and demonstrate its accuracy in modeling human longevity data from life tables. The new distribution is characterized by 1. An intuitively straightforward genesis; 2. Closed forms for the pdf, cdf, mode, quantile, and hazard functions; and 3. Accessibility to non-statisticians, based on its close relationship to the normal distribution.

  11. SOME IMPORTANT STATISTICAL PROPERTIES, INFORMATION MEASURES AND ESTIMATIONS OF SIZE BIASED GENERALIZED GAMMA DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    J. A. Reshi

    2014-12-01

    Full Text Available In this paper, a new class of Size-biased Generalized Gamma (SBGG distribution is defined. A Size-biased Generalized Gamma (SBGG distribution, a particular case of weighted Generalized Gamma distribution, taking the weights as the variate values has been defined. The important statistical properties including hazard functions, reverse hazard functions, mode, moment generating function, characteristic function, Shannon’s entropy, generalized entropy and Fisher’s information matrix of the new model have been derived and studied. Here, we also study SBGG entropy estimation, Akaike and Bayesian information criterion. A likelihood ratio test for size-biasedness is conducted. The estimation of parameters is obtained by employing the classical methods of estimation especially method of moments and maximum likelihood estimator.

  12. A general formalism for single and double spin asymmetries in inclusive hadron production

    CERN Document Server

    D'Alesio, U; Murgia, F

    2004-01-01

    We present a calculation of single and double spin asymmetries for inclusive hadron production in hadronic collisions. Our approach is based on Leading Order (LO) perturbative QCD and generalized factorization theorems, with full account of intrinsic parton momentum, k_T, effects. This leads to a new class of spin and k_T-dependent distribution and fragmentation functions. Limiting ourselves to consider leading twist functions, we show how they could play a relevant role in producing non-vanishing spin asymmetries.

  13. New single- and double-parton scattering mechanisms for double charmed meson production

    CERN Document Server

    Szczurek, Antoni; Saleev, Vladimir A; Shipilova, Alexandra V

    2016-01-01

    We discuss charm meson-meson pair production recently observed by the LHCb Collaboration at $\\sqrt{s}$ = 7 TeV in proton-proton scattering. We examine double-parton scattering (DPS) mechanisms of double $c \\bar c$ production and following $cc \\to D^{0}D^{0}$ hadronization as well as double $g$ and mixed $g c\\bar c $ production with $gg \\to D^{0}D^{0}$ and $gc \\to D^{0}D^{0}$ hadronization calculated with the help of the scale-dependent KKKS08 fragmentation functions. A new single-parton scattering (SPS) mechanism of $gg$ production is also taken into consideration. Calculated differential distributions as a function of transverse momentum $p_{T}$ of one of the $D^{0}$ mesons, pair invariant mass $M_{D^{0}D^{0}}$ and azimuthal angle $\\varphi_{D^{0}D^{0}}$ distributions are confronted with the measured ones. The manifestation of the new SPS mechanisms with $g \\to D^{0}$ fragmentation within the scale-dependent fragmentation scheme change the overall picture suitable for standard scale-independent fragmentation ...

  14. General-purpose event generators for LHC physics

    CERN Document Server

    Buckley, Andy; Gieseke, Stefan; Grellscheid, David; Hoche, Stefan; Hoeth, Hendrik; Krauss, Frank; Lonnblad, Leif; Nurse, Emily; Richardson, Peter; Schumann, Steffen; Seymour, Michael H; Sjostrand, Torbjorn; Skands, Peter; Webber, Bryan

    2011-01-01

    We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton-proton collisions at the Large Hadron Collider. Topics included are: the generation of hard-scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond-Standard-Model processes. We describe the principal features of the ARIADNE, Herwig++, PYTHIA 8 and SHERPA generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators ...

  15. Distributional Assumptions in Educational Assessments Analysis: Normal Distributions versus Generalized Beta Distribution in Modeling the Phenomenon of Learning

    Science.gov (United States)

    Campos, Jose Alejandro Gonzalez; Moraga, Paulina Saavedra; Del Pozo, Manuel Freire

    2013-01-01

    This paper introduces the generalized beta (GB) model as a new modeling tool in the educational assessment area and evaluation analysis, specifically. Unlike normal model, GB model allows us to capture some real characteristics of data and it is an important tool for understanding the phenomenon of learning. This paper develops a contrast with the…

  16. Distribution of the LR criterion Up,m,n as a marginal distribution of a generalized Dirichlet model

    Directory of Open Access Journals (Sweden)

    Seemon Thomas

    2013-05-01

    Full Text Available The density of the likelihood ratio criterion Up,m,n is expressed in terms of a marginal density of a generalized Dirichlet model having a specific set of parameters. The exact distribution of the likelihood ratio criterion so obtained has a very simple and general format for every p . It provides an easy and direct method of computation of the exact p -value of Up,m,n . Various types of properties and relations involving hypergeometric series are also established.

  17. KaTie: for parton-level event generation with k_T-dependent initial states

    CERN Document Server

    van Hameren, A

    2016-01-01

    KaTie is a parton-level event generator for hadron scattering processes that can deal with partonic initial-state momenta with an explicit transverse momentum dependence causing them to be space-like. Provided with the necessary transverse momentum dependent parton density functions, it calculates the off-shell matrix elements and performs the phase space importance sampling to produce weighted events, for example in the Les Houches Event File format. It can deal with arbitrary processes within the Standard Model, for up to four final-state particles and beyond. Furthermore, it can produce events for single-parton scattering as well as for multi-parton scattering.

  18. A New Insight into the Earthquake Recurrence Studies from the Three-parameter Generalized Exponential Distributions

    Science.gov (United States)

    Pasari, S.; Kundu, D.; Dikshit, O.

    2012-12-01

    Earthquake recurrence interval is one of the important ingredients towards probabilistic seismic hazard assessment (PSHA) for any location. Exponential, gamma, Weibull and lognormal distributions are quite established probability models in this recurrence interval estimation. However, they have certain shortcomings too. Thus, it is imperative to search for some alternative sophisticated distributions. In this paper, we introduce a three-parameter (location, scale and shape) exponentiated exponential distribution and investigate the scope of this distribution as an alternative of the afore-mentioned distributions in earthquake recurrence studies. This distribution is a particular member of the exponentiated Weibull distribution. Despite of its complicated form, it is widely accepted in medical and biological applications. Furthermore, it shares many physical properties with gamma and Weibull family. Unlike gamma distribution, the hazard function of generalized exponential distribution can be easily computed even if the shape parameter is not an integer. To contemplate the plausibility of this model, a complete and homogeneous earthquake catalogue of 20 events (M ≥ 7.0) spanning for the period 1846 to 1995 from North-East Himalayan region (20-32 deg N and 87-100 deg E) has been used. The model parameters are estimated using maximum likelihood estimator (MLE) and method of moment estimator (MOME). No geological or geophysical evidences have been considered in this calculation. The estimated conditional probability reaches quite high after about a decade for an elapsed time of 17 years (i.e. 2012). Moreover, this study shows that the generalized exponential distribution fits the above data events more closely compared to the conventional models and hence it is tentatively concluded that generalized exponential distribution can be effectively considered in earthquake recurrence studies.

  19. Nucleon partonic spin structure to be explored by the unpolarized Drell-Yan program of COMPASS experiment at CERN

    CERN Document Server

    Chang, Wen-Chen

    2016-01-01

    The observation of the violation of Lam-Tung relation in the $\\pi N$ Drell-Yan process triggered many theoretical speculations. The TMD Boer-Mulders functions characterizing the correlation of transverse momentum and transverse spin for partons in unpolarized hadrons could nicely account for the violation. The COMPASS experiment at CERN will measure the angular distributions of dimuons from the unpolarized Drell-Yan process over a wide kinematic region and study the beam particle dependence. Significant statistics is expected from a successful run in 2015 which will bring further understanding of the origin of the violation of Lam-Tung relation and of the partonic transverse spin structure of the nucleon.

  20. $\\kappa$-generalized models of income and wealth distributions: A survey

    CERN Document Server

    Clementi, F; Kaniadakis, G; Landini, S

    2016-01-01

    The paper provides a survey of results related to the "$\\kappa$-generalized distribution", a statistical model for the size distribution of income and wealth. Topics include, among others, discussion of basic analytical properties, interrelations with other statistical distributions as well as aspects that are of special interest in the income distribution field, such as the Gini index and the Lorenz curve. An extension of the basic model that is most able to accommodate the special features of wealth data is also reviewed. The survey of empirical applications given in this paper shows the $\\kappa$-generalized models of income and wealth to be in excellent agreement with the observed data in many cases.