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Sample records for nucleon generalized parton

  1. Insight into nucleon structure from generalized parton distributions

    International Nuclear Information System (INIS)

    J.W. Negele; R.C. Brower; P. Dreher; R. Edwards; G. Fleming; Ph. Hagler; Th. Lippert; A.V.Pochinsky; D.B. Renner; D. Richards; K. Schilling; W. Schroers

    2004-01-01

    The lowest three moments of generalized parton distributions are calculated in full QCD and provide new insight into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon

  2. Nucleon generalized parton distributions from full lattice QCD

    International Nuclear Information System (INIS)

    Haegler, P.; Schroers, W.; Bratt, J.; Negele, J.W.; Pochinsky, A.V.

    2007-07-01

    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 . (orig.)

  3. Chiral perturbation theory for nucleon generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Manashov, A. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik]|[Sankt-Petersburg State Univ. (Russian Federation). Dept. of Theoretical Physics; Schaefer, A. [Regensburg Univ. (Germany). Inst. fuer Physik 1 - Theoretische Physik

    2006-08-15

    We analyze the moments of the isosinglet generalized parton distributions H, E, H, E of the nucleon in one-loop order of heavy-baryon chiral perturbation theory. We discuss in detail the construction of the operators in the effective theory that are required to obtain all corrections to a given order in the chiral power counting. The results will serve to improve the extrapolation of lattice results to the chiral limit. (orig.)

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

    International Nuclear Information System (INIS)

    Diehl, Markus; Kroll, Peter; Regensburg Univ.

    2013-02-01

    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 μ=2 GeV to be J u v =0.230 +0.009 -0.024 and J d v =-0.004 +0.010 -0.016 .

  5. 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}.

  6. Moments of nucleon generalized parton distributions from lattice QCD

    International Nuclear Information System (INIS)

    Alexandrou, C.; Cyprus Institute, Nicosia; Carbonell, J.; Harraud, P.A.; Papinutto, M.; Constantinou, M.; Kallidonis, C.; Guichon, P.; Jansen, K.; Korzec, T.; Humboldt Univ. Berlin

    2011-07-01

    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 μ=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.)

  7. Nucleon parton distributions in chiral perturbation theory

    International Nuclear Information System (INIS)

    Moiseeva, Alena

    2013-01-01

    Properties of the chiral expansion of nucleon light-cone operators have been studied. In the framework of the chiral perturbation theory we have demonstrated that convergency of the chiral expansion of nucleon parton distributions strongly depends on the value of the variable x. Three regions in x with essentially different analytical properties of the resulting chiral expansion for parton distributions were found. For each of the regions we have elaborated special power counting rules corresponding to the partial resummation of the chiral series. The nonlocal effective operators for the vector and the axial nucleon parton distributions have been constructed at the zeroth and the first chiral order. Using the derived nonlocal operators and the derived power counting rules we have obtained the second order expressions for the nucleon GPDs H(x,ξ,Δ 2 ), H(x,ξ,Δ 2 ),E(x,ξ,Δ 2 ) valid in the region x>or similar a 2 χ .

  8. 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.

  9. Baryon form factors at high momentum transfer and generalized parton distributions

    International Nuclear Information System (INIS)

    Stoler, Paul

    2002-01-01

    Nucleon form factors at high momentum transfer t are treated in the framework of generalized parton distributions (GPD's). The possibility of obtaining information about parton high transverse momentum components by application of GPD's to form factors is discussed. This is illustrated by applying an ad hoc 2-body parton wave function to elastic nucleon form factors F 1 and F 2 , the N→Δ transition magnetic form factor G M * , and the wide angle Compton scattering form factor R 1

  10. Momentum transfer dependence of generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Neetika [Indian Institute of Science Education and Research Mohali, S.A.S. Nagar, Punjab (India)

    2016-11-15

    We revisit the model for parametrization of the momentum dependence of nucleon generalized parton distributions in the light of recent MRST measurements of parton distribution functions (A.D. Martin et al., Eur. Phys. J. C 63, 189 (2009)). Our parametrization method with a 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-quarks by decomposing the electromagnetic form factors for the 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 Kelly's distribution. (orig.)

  11. Study of generalized parton distributions and deeply virtual Compton scattering on the nucleon with the CLAS and CLAS12 detectors at the Jefferson Laboratory (Virginia, US)

    International Nuclear Information System (INIS)

    Guegan, B.

    2012-11-01

    The Generalized Parton Distributions (GPDs) provide a new description of the nucleon structure in terms of its elementary constituents, the quarks and the gluons. The GPDs give access to a unified picture of the nucleon, correlating the information obtained from the measurements of the Form Factors and the Parton Distribution Functions. They describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark of the nucleon eN → e'N'γ, is the most straightforward exclusive process allowing access to the GPDs. A dedicated experiment to study DVCS with the CLAS detector of Jefferson Lab has been carried out using a 5.883 GeV polarized electron beam and an unpolarized hydrogen target, allowing to collect DVCS events in the widest kinematic range ever explored in the valence region: 1 2 2 , 0.1 B 2 . In this work, we present the extraction of three different DVCS observables: the unpolarized cross section, the difference of polarized cross sections and the beam spin asymmetry. We present comparisons with GPD model. We show a preliminary extraction of the GPDs using the latest fitting code procedure on our data, and a preliminary interpretation of the results in terms of parton density. (author)

  12. 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.

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

    International Nuclear Information System (INIS)

    Gutsche, Thomas; Lyubovitskij, Valery E.; Schmidt, Ivan

    2017-01-01

    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_v(x) and δq_v(x). Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN). (orig.)

  14. 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.)

  15. 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.

  16. Experimental studies of generalized parton distributions

    International Nuclear Information System (INIS)

    Kabuss, E.M.

    2014-01-01

    Generalized parton distributions (GPD) provide a new way to study the nucleon structure. Experimentally they can be accessed using hard exclusive processes such as deeply virtual Compton scattering and meson production. First insights to GPDs were already obtained from measurements at DESY, JLAB and CERN, while new ambitious studies are planned at the upgraded JLAB at 12 GeV and at CERN. Here, some emphasis will be put onto the planned COMPASS II programme. (author)

  17. An introduction to the Generalized Parton Distributions

    International Nuclear Information System (INIS)

    Michel Garcon

    2002-01-01

    The concepts of Generalized Parton Distributions (GPD) are reviewed in an introductory and phenomenological fashion. These distributions provide a rich and unifying picture of the nucleon structure. Their physical meaning is discussed. The GPD are in principle measurable through exclusive deeply virtual production of photons (DVCS) or of mesons (DVMP). Experiments are starting to test the validity of these concepts. First results are discussed and new experimental projects presented, with an emphasis on this program at Jefferson Lab

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

    Indian Academy of Sciences (India)

    2016-01-12

    Jan 12, 2016 ... 1. Introduction. Generalized parton distributions (GPDs) are the important set of parameters that give us ... The AdS/CFT is the correspondence between the string theory on a higher-dimensional anti-de Sitter ... matching the soft-wall model of AdS/QCD and light-front QCD for EFFs of hadrons with arbitrary ...

  19. On chiral-odd Generalized Parton Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Wallon, Samuel [Laboratoire de Physique Theorique d' Orsay - LPT, Bat. 210, Univ. Paris-Sud 11, 91405 Orsay Cedex (France); UPMC Univ. Paris 6, Paris (France); Pire, Bernard [Centre de Physique Theorique - CPHT, UMR 7644, Ecole Polytechnique, Bat. 6, RDC, F91128 Palaiseau Cedex (France); Szymanowski, Lech [Soltan Institute for Nuclear Studies, Hoza 69, 00691, Warsaw (Poland)

    2010-07-01

    The chiral-odd transversity generalized parton distributions of the nucleon can be accessed experimentally through the exclusive photoproduction process {gamma} + N {yields} {pi} + {rho} + N', in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversally polarized state. Estimated counting rates show that the experiment is feasible with real or quasi real photon beams expected at JLab at 12 GeV and in the COMPASS experiment. (Phys Letters B688,154,2010) In addition, a consistent classification of the chiral-odd pion GPDs beyond the leading twist 2 is presented. Based on QCD equations of motion and on the invariance under rotation on the light-cone of any scattering amplitude involving such GPDs, we reduce the basis of these chiral-odd GPDs to a minimal set. (author)

  20. Helicity-dependent generalized parton distributions for nonzero skewness

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Chandan [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China)

    2017-09-15

    We investigate the helicity-dependent generalized parton distributions (GPDs) in momentum as well as transverse position (impact) spaces for the u and d quarks in a proton when the momentum transfer in both the transverse and the longitudinal directions are nonzero. The GPDs are evaluated using the light-front wave functions of a quark-diquark model for nucleon where the wave functions are constructed by the soft-wall AdS/QCD correspondence. We also express the GPDs in the boost-invariant longitudinal position space. (orig.)

  1. 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.)

  2. The multidimensional nucleon structure

    Directory of Open Access Journals (Sweden)

    Pasquini Barbara

    2016-01-01

    Full Text Available We discuss different kinds of parton distributions, which allow one to obtain a multidimensional picture of the internal structure of the nucleon. We use the concept of generalized transverse momentum dependent parton distributions and Wigner distributions, which combine the features of transverse-momentum dependent parton distributions and generalized parton distributions. We show examples of these functions within a phenomenological quark model, with focus on the role of the spin-spin and spin-orbit correlations of quarks.

  3. Generalized parton distribution for non zero skewness

    International Nuclear Information System (INIS)

    Kumar, Narinder; Dahiya, Harleen; Teryaev, Oleg

    2012-01-01

    In the theory of strong interactions the main open question is how the nucleon and other hadrons are built from quarks and gluons, the fundamental degrees of freedom in QCD. An essential tool to investigate hadron structure is the study of deep inelastic scattering processes, where individual quarks and gluons can be resolved. The parton densities extracted from such processes encode the distribution of longitudinal momentum and polarization carried by quarks, antiquarks and gluons within a fast moving hadron. They have provided much to shape the physical picture of hadron structure. In the recent years, it has become clear that appropriate exclusive scattering processes may provide such information encoded in the general parton distributions (GPDs). Here, we investigate the GPD for deep virtual compton scattering (DVCS) for the non zero skewness. The study has investigated the GPDs by expressing them in terms of overlaps of light front wave functions (LFWFs). The work represented a spin 1/2 system as a composite of spin 1/2 fermion and spin 1 boson with arbitrary masses

  4. Dynamical parton distributions of the nucleon and very small-x physics

    International Nuclear Information System (INIS)

    Glueck, M.; Jimenez-Delgado, P.; Reya, E.

    2008-01-01

    Utilizing recent DIS measurements (F 2,L ) and data on dilepton and high-E T jet production we determine the dynamical parton distributions of the nucleon generated radiatively from valence-like positive input distributions at optimally chosen low resolution scales. These are compared with 'standard' distributions generated from positive input distributions at some fixed and higher resolution scale. It is shown that up to the next-to-leading order NLO(MS, DIS) of perturbative QCD considered in this paper, the uncertainties of the dynamical distributions are, as expected, smaller than those of their standard counterparts. This holds true in particular in the presently unexplored extremely small-x region relevant for evaluating ultrahigh energy cross sections in astrophysical applications. It is noted that our new dynamical distributions are compatible, within the presently determined uncertainties, with previously determined dynamical parton distributions. (orig.)

  5. Moments of nucleon spin-dependent generalized parton distributions

    International Nuclear Information System (INIS)

    Schroers, W.; Brower, R.C.; Dreher, P.; Edwards, R.; Fleming, G.; Haegler, Ph.; Heller, U.M.; Lippert, Th.; Negele, J.W.; Pochinsky, A.V.; Renner, D.B.; Richards, D.; Schilling, K.

    2004-01-01

    We present a lattice measurement of the first two moments of the spin-dependent GPD H∼(x, ξ, t). From these we obtain the axial coupling constant and the second moment of the spin-dependent forward parton distribution. The measurements are done in full QCD using Wilson fermions. In addition, we also present results from a first exploratory study of full QCD using Asqtad sea and domain-wall valence fermions

  6. Universality of Generalized Parton Distributions in Light-Front Holographic QCD

    Science.gov (United States)

    de Téramond, Guy F.; Liu, Tianbo; Sufian, Raza Sabbir; Dosch, Hans Günter; Brodsky, Stanley J.; Deur, Alexandre; Hlfhs Collaboration

    2018-05-01

    The structure of generalized parton distributions is determined from light-front holographic QCD up to a universal reparametrization function w (x ) which incorporates Regge behavior at small x and inclusive counting rules at x →1 . A simple ansatz for w (x ) that fulfills these physics constraints with a single-parameter results in precise descriptions of both the nucleon and the pion quark distribution functions in comparison with global fits. The analytic structure of the amplitudes leads to a connection with the Veneziano model and hence to a nontrivial connection with Regge theory and the hadron spectrum.

  7. Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC

    Energy Technology Data Exchange (ETDEWEB)

    L. Frankfurt, M. Strikman, C. Weiss

    2011-03-01

    We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/\\gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process.

  8. Nuclear physics aspects in the parton model of Feynman

    International Nuclear Information System (INIS)

    Pauchy Hwang, W.Y.

    1995-01-01

    The basic fact that pions couple strongly to nucleons has dominated various nuclear physics thinkings since the birth of the field more than sixty years ago. The parton model of Feynman, in which the structure of a nucleon (or a hadron) is characterized by a set of parton distributions, was proposed originally in late 1960's to treat high energy deep inelastic scattering, and later many other high energy physics experiments involving hadrons. Introduction of the concept of parton distributions signifies the departure of particle physics from nuclear physics. Following the suggestion that the sea quark distributions in a nucleon, at low and moderate Q 2 (at least up to a few GeV 2 ), can be attributed primarily to the probability of finding such quarks or antiquarks in the mesons (or recoiling baryons) associated with the nucleon, the author examines how nuclear physics aspects offer quantitative understanding of several recent experimental results, including the observed violation of the Gotfried sum rule and the so-called open-quotes proton spin crisisclose quotes. These results suggest that determination of parton distributions of a hadron at Q 2 of a few GeV 2 (and at small x) must in general take into account nuclear physics aspects. Implication of these results for other high-energy reactions, such as semi-inclusive hadron production in deep inelastic scattering, are also discussed

  9. Study of the partonic structure of the helium nucleus

    International Nuclear Information System (INIS)

    Perrin, Y.

    2012-01-01

    The structure of the nucleons and of the nuclei was actively studied during the twentieth century through electron elastic scattering (measuring the electromagnetic form factors) and deep inelastic electron scattering (measuring the parton distributions). The formalism of generalized parton distributions (GPD) achieved the unification of the form factors and the parton distributions. This link gives a source of information about parton dynamics, such as the distribution of nuclear forces and orbital momentum inside hadrons. The easiest experimental access to the GPD is the deeply virtual Compton scattering (DVCS), which corresponds to the hard electroproduction of a real photon. While several experiments focussed on DVCS off the nucleon, only a few experiments studied DVCS off a nuclear target. This thesis deals with the study of the coherent channel of DVCS off helium 4, with the aim of extracting the real and imaginary parts of the Compton form factor thanks to the beam spin asymmetry. (author)

  10. 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...

  11. 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.

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

    International Nuclear Information System (INIS)

    Pire, B.; Semenov-Tian-Shansky, K.; Szymanowski, L.; Wallon, S.

    2014-01-01

    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.)

  13. 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.)

  14. Unbiased global determination of parton distributions and their uncertainties at NNLO and at LO

    NARCIS (Netherlands)

    Collaboration, The NNPDF; Ball, Richard D.; Bertone, Valerio; Cerutti, Francesco; Debbio, Luigi Del; Forte, Stefano; Guffanti, Alberto; Latorre, Jose I.; Rojo, Juan; Ubiali, Maria

    2012-01-01

    We present a determination of the parton distributions of the nucleon from a global set of hard scattering data using the NNPDF methodology at LO and NNLO in perturbative QCD, thereby generalizing to these orders the NNPDF2.1 NLO parton set. Heavy quark masses are included using the so-called FONLL

  15. Exclusive neutrino production of a charmed vector meson and transversity gluon generalized parton distributions

    Science.gov (United States)

    Pire, B.; Szymanowski, L.

    2017-12-01

    We calculate at the leading order in αs the QCD amplitude for exclusive neutrino production of a D* or Ds* charmed vector meson on a nucleon. We work in the framework of the collinear QCD approach where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We include O (mc) terms in the coefficient functions and the O (mD) term in the definition of heavy meson distribution amplitudes. The show that the analysis of the angular distribution of the decay D(s) *→D(s )π allows us to access the transversity gluon GPDs.

  16. Future exploration of the nucleon structure at COMPASS

    International Nuclear Information System (INIS)

    Marchand, Claude

    2011-01-01

    Up to now, COMPASS experiment essentially focussed, in it's program with muon beams, on studying aspects of the longitudinal momentum structure of the nucleon in the collinear approximation, like Δq(x) and ΔG/G(x). However, quarks can also have intrinsic transverse momentum in the nucleon, which give rise to a new class of Transverse Momentum Distribution (TMD) Parton Distribution Functions. As an example, Sievers function has been measured by both COMPASS and HERMES to be non zero on the proton, paving thus the way for more precise investigations. It is precisely the goal of the new COMPASS phase II proposal to investigate in more detail new transverse description of the nucleon structure. Deeply Virtual Compton Scattering (DVCS) will allow studies in the transverse space via Generalized Parton Distributions (GPDs). Transverse Mometum Dependent PDFs will essentially be studied in Drell-Yan (DY) reaction and SIDIS, and some universality arguments in QCD imply different signs for Sievers and Boer-Mulders functions in DY and SIDIS.

  17. Charge symmetry breaking in spin dependent parton distributions and the Bjorken sum rule

    International Nuclear Information System (INIS)

    Cloet, I.C.; Horsley, R.; Londergan, J.T.

    2012-04-01

    We present the rst determination of charge symmetry violation (CSV) in the spin-dependent parton distribution functions of the nucleon. This is done by determining the rst two Mellin moments of the spin-dependent parton distribution functions of the octet baryons from N f =2+1 lattice simulations. The results are compared with predictions from quark models of nucleon structure. We discuss the contribution of partonic spin CSV to the Bjorken sum rule, which is important because the CSV contributions represent the only partonic corrections to the Bjorken sum rule.

  18. Charge symmetry breaking in spin dependent parton distributions and the Bjorken sum rule

    Energy Technology Data Exchange (ETDEWEB)

    Cloet, I.C. [Adelaide Univ, SA (Australia). CSSM, School of Chemistry and Physics; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Londergan, J.T. [Indiana Univ., Bloomington, IN (US). Dept. of Physics and Center for Exploration of Energy and Matter] (and others)

    2012-04-15

    We present the rst determination of charge symmetry violation (CSV) in the spin-dependent parton distribution functions of the nucleon. This is done by determining the rst two Mellin moments of the spin-dependent parton distribution functions of the octet baryons from N{sub f}=2+1 lattice simulations. The results are compared with predictions from quark models of nucleon structure. We discuss the contribution of partonic spin CSV to the Bjorken sum rule, which is important because the CSV contributions represent the only partonic corrections to the Bjorken sum rule.

  19. Photoproduction of a πρT pair with a large invariant mass and transversity generalized parton distribution

    International Nuclear Information System (INIS)

    El Beiyad, M.; Pire, B.; Segond, M.; Szymanowski, L.; Wallon, S.

    2010-01-01

    The chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed experimentally through the exclusive photoproduction process γ+N→π+ρ+N ' , in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversally polarized state. We calculate perturbatively the scattering amplitude at leading order in α s . We build a simple model for the dominant transversity GPD H T (x,ξ,t) based on the concept of double distribution. We estimate the unpolarized differential cross section for this process in the kinematics of the Jlab and Compass experiments. Counting rates show that the experiment looks feasible with the real photon beam characteristics expected at JLab-12 GeV, and with the quasi real photon beam in the Compass experiment.

  20. Novel applications of Lattice QCD: Parton Distributions, proton charge radius and neutron electric dipole moment

    Directory of Open Access Journals (Sweden)

    Alexandrou Constantia

    2017-01-01

    Full Text Available We briefly discuss the current status of lattice QCD simulations and review selective results on nucleon observables focusing on recent developments in the lattice QCD evaluation of the nucleon form factors and radii, parton distribution functions and their moments, and the neutron electric dipole moment. Nucleon charges and moments of parton distribution functions are presented using simulations generated at physical values of the quark masses, while exploratory studies are performed for the parton distribution functions and the neutron electric dipole moment at heavier than physical value of the pion mass.

  1. Exclusive electroproduction of lepton pairs as a probe of nucleon structure

    International Nuclear Information System (INIS)

    Belitsky, A.V.; Mueller, D.

    2003-01-01

    We suggest the measurement of exclusive electroproduction of lepton pairs as a tool to study interparton correlations in the nucleon via generalized parton distributions in the kinematical region where this process is light-cone dominated. We demonstrate how the single beam-spin asymmetry allows one to perform such a kind of analysis and give a number of predictions for several experimental setups. We comment on other observables which allow for a clean separation of different species of generalized parton distributions

  2. Moments of nucleon's parton distribution for the sea and valence quarks from lattice QCD

    International Nuclear Information System (INIS)

    Deka, M.; Doi, T.; Dong, S. J.; Draper, T.; Liu, K. F.; Streuer, T.; Mathur, N.; Thomas, A. W.

    2009-01-01

    We extend the study of lowest moments, and 2 >, of the parton distribution function of the nucleon to include those of the sea quarks; this entails a disconnected insertion calculation in lattice QCD. This is carried out on a 16 3 x24 quenched lattice with Wilson fermion. The quark loops are calculated with Z 2 noise vectors and unbiased subtractions, and multiple nucleon sources are employed to reduce the statistical errors. We obtain 5σ signals for for the u, d, and s quarks, but 2 > is consistent with zero within errors. We provide results for both the connected and disconnected insertions. The perturbatively renormalized for the strange quark at μ=2 GeV is s+s =0.027±0.006 which is consistent with the experimental result. The ratio of for s vs u/d in the disconnected insertion with quark loops is calculated to be 0.88±0.07. This is about twice as large as the phenomenologically fitted ( s+s / u + d ) from experiments where u and d include both the connected and disconnected insertion parts. We discuss the source and implication of this difference.

  3. Form factors and other measures of strangeness in the nucleon

    International Nuclear Information System (INIS)

    Diehl, M.; Feldmann, T.; Kroll, P.

    2007-11-01

    We discuss the phenomenology of strange-quark dynamics in the nucleon, based on experimental and theoretical results for electroweak form factors and for parton densities. In particular, we construct a model for the generalized parton distribution that relates the asymmetry s(x)- anti s(x) between the longitudinal momentum distributions of strange quarks and antiquarks with the form factor F s 1 (t), which describes the distribution of strangeness in transverse position space. (orig.)

  4. Deeply virtual Compton scattering with the CLAS detector for the study of generalized parton distributions

    International Nuclear Information System (INIS)

    Girod, F.X.

    2006-12-01

    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 → epγ 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)

  5. New large-Nc relations among the nucleon and nucleon-to-Delta GPDs

    International Nuclear Information System (INIS)

    Marc Vanderhaeghen; Vladimir Pascalutsa

    2006-01-01

    We establish relations which express the generalized parton distributions (GPDs) describing the N → Δ transition in terms of the nucleon GPDs. These relations are based on the known large-N c relation between the N → Δ electric quadrupole moment and the neutron charge radius, and a newly derived large-N c relation between the electric quadrupole (E2) and Coulomb quadrupole (C2) transitions. Namely, in the large-N c limit we find C2=E2. The resulting relations among the nucleon and N → Δ GPDs provide predictions for the N → Δ electromagnetic form factors which are found to be in very good agreement with experiment for moderate momentum transfers

  6. Photoproduction of a pirho{sub T} pair with a large invariant mass and transversity generalized parton distribution

    Energy Technology Data Exchange (ETDEWEB)

    El Beiyad, M. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); LPT, Universite d' Orsay, CNRS, 91404 Orsay (France); Pire, B. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Segond, M. [Institut fuer Theoretische Physik, Universitaet Leipzig, D-04009 Leipzig (Germany); Szymanowski, L. [Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Soltan Institute for Nuclear Studies, Warsaw (Poland); Wallon, S., E-mail: Samuel.Wallon@th.u-psud.f [LPT, Universite d' Orsay, CNRS, 91404 Orsay (France); UPMC, Univ. Paris 06, Faculte de physique, 4 place Jussieu, 75252 Paris Cedex 05 (France)

    2010-05-03

    The chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed experimentally through the exclusive photoproduction process gamma+N->pi+rho+N{sup '}, in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversally polarized state. We calculate perturbatively the scattering amplitude at leading order in alpha{sub s}. We build a simple model for the dominant transversity GPD H{sub T}(x,xi,t) based on the concept of double distribution. We estimate the unpolarized differential cross section for this process in the kinematics of the Jlab and Compass experiments. Counting rates show that the experiment looks feasible with the real photon beam characteristics expected at JLab-12 GeV, and with the quasi real photon beam in the Compass experiment.

  7. Spin-dependent parton distributions in the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Cloet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, SA 5005 (Australia); Bentz, W. [Department of Physics, School of Science, Tokai University Hiratsuka-shi, Kanagawa 259-1292 (Japan); Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)

    2005-04-15

    Spin-dependent quark light-cone momentum distributions are calculated for a nucleon in the nuclear medium. We utilize a modified NJL model where the nucleon is described as a composite quark-diquark state. Scalar and vector mean fields are incorporated in the nuclear medium and these fields couple to the confined quarks in the nucleon. The effect of these fields on the spin-dependent distributions and consequently the axial charges is investigated. Our results for the 'spin-dependent EMC effect' are also discussed.

  8. Nucleon fragmentation into baryons in proton-nucleon interactions at 19 GeV/c compared with some quark-parton model predictions

    Energy Technology Data Exchange (ETDEWEB)

    Bakken, V.; Breivik, F.O.; Jacobsen, T. (Oslo Univ. (Norway). Fysisk Inst.)

    1983-06-21

    We present some new data on baryon production in pn interactions at 19 GeV/c obtained in a bubble chamber experiment. We determine the longitudinal-momentum spectra dsigma/dx of the baryon in the reaction pn->psub(F)+X, pn->psub(B)+X, pn->..delta..sub(F)/sup + +/(1232)+X and pn->..delta..sub(B)/sup + +/(1232)+X, where F(B) labels the forward (backward) c.m. hemisphere. The spectra of psub(F) and psub(B) are also given when the effects of diffraction and ..delta../sup + +/(1232) resonance production are substracted. These data, together with dsigma/dx of pp->..lambda../sup 0/+X at the same beam momentum, are compared with the predictions of some quark-parton models. Particle multiplicities of nucleons, ..delta../sup + +/(1232) and hyperons are found to be incompatible with the probabilistic quark model of Van Hove.

  9. Form factors and other measures of strangeness in the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Feldmann, T. [Siegen Univ. (Germany). Theoretische Physik I; Kroll, P. [Bergische Univ., Wuppertal (Germany). Fachbereich Physik

    2007-11-15

    We discuss the phenomenology of strange-quark dynamics in the nucleon, based on experimental and theoretical results for electroweak form factors and for parton densities. In particular, we construct a model for the generalized parton distribution that relates the asymmetry s(x)- anti s(x) between the longitudinal momentum distributions of strange quarks and antiquarks with the form factor F{sup s}{sub 1}(t), which describes the distribution of strangeness in transverse position space. (orig.)

  10. Generalized Parton Distributions and their Singularities

    Energy Technology Data Exchange (ETDEWEB)

    Anatoly Radyushkin

    2011-04-01

    A new approach to building models of generalized parton distributions (GPDs) is discussed that is based on the factorized DD (double distribution) Ansatz within the single-DD formalism. The latter was not used before, because reconstructing GPDs from the forward limit one should start in this case with a very singular function $f(\\beta)/\\beta$ rather than with the usual parton density $f(\\beta)$. This results in a non-integrable singularity at $\\beta=0$ exaggerated by the fact that $f(\\beta)$'s, on their own, have a singular $\\beta^{-a}$ Regge behavior for small $\\beta$. It is shown that the singularity is regulated within the GPD model of Szczepaniak et al., in which the Regge behavior is implanted through a subtracted dispersion relation for the hadron-parton scattering amplitude. It is demonstrated that using proper softening of the quark-hadron vertices in the regions of large parton virtualities results in model GPDs $H(x,\\xi)$ that are finite and continuous at the "border point'' $x=\\xi$. Using a simple input forward distribution, we illustrate the implementation of the new approach for explicit construction of model GPDs. As a further development, a more general method of regulating the $\\beta=0$ singularities is proposed that is based on the separation of the initial single DD $f(\\beta, \\alpha)$ into the "plus'' part $[f(\\beta,\\alpha)]_{+}$ and the $D$-term. It is demonstrated that the "DD+D'' separation method allows to (re)derive GPD sum rules that relate the difference between the forward distribution $f(x)=H(x,0)$ and the border function $H(x,x)$ with the $D$-term function $D(\\alpha)$.

  11. Diquark contributions to the nucleon deep inelastic structure functions

    International Nuclear Information System (INIS)

    Anselmino, M.; Leader, E.; Soares, J.

    1990-01-01

    The contributions of diquarks to the nucleon structure functions are discussed in the framework of the parton model and in the most general case of both vector and scalar diquarks inside unpolarized and polarized nucleons. The vector diquark anomalous magnetic moment and the scalar-vector and vector-scalar diquark transitions are also taken into account. The properties of the diquarks and of their form factors, required in order for the resulting scaling violations to be compatible with the observed ones, are discussed. (author)

  12. Quarks and partons

    International Nuclear Information System (INIS)

    Close, F.E.

    1976-01-01

    The studies of inelastic electron scattering at SLAC and of neutrino scattering at CERN have been widely interpreted as giving support to the idea that the nucleon is built from elementary constituents, called partons, and that these partons have the same quantum numbers as the quarks that are familiar in spectroscopy. In particular, a very simple regularity in the data, known as scale invariance or just 'scaling' was seen at least at moderate energies (2 2 > approximately 1 GeV) which is natural in the parton model. The data on e + e - annihilation also appear to be consistent with scaling when Esub(cm) approximately 5 GeV. These lectures are concerned with the scaling phenomena. One may expect the new hadronic degree of freedom to generate scaling violations in inelastic electron and neutrino scattering. These are mentioned briefly in these lectures. (Auth.)

  13. 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...... fraction of the proton. We also present collider PDF sets, constructed using only data from HERA, the Tevatron and the LHC, but find that this data set is neither precise nor complete enough for a competitive PDF determination....

  14. Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions

    Science.gov (United States)

    Jo, H. S.; Girod, F. X.; Avakian, H.; Burkert, V. D.; Garçon, M.; Guidal, M.; Kubarovsky, V.; Niccolai, S.; Stoler, P.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Compton, N.; 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.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Harrison, N.; Hattawy, M.; Hicks, K.; Hirlinger Saylor, N.; Ho, D.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; McKinnon, B.; Meziani, Z. E.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Movsisyan, A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Net, L. A.; Niculescu, G.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Park, K.; Pasyuk, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Simonyan, A.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.; CLAS Collaboration

    2015-11-01

    Unpolarized and beam-polarized fourfold cross sections (d4σ /d Q2d xBd t d ϕ ) for the e p →e'p'γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q2,xB,t ) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H , expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction xB.

  15. 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)

  16. Parton distributions with LHC data

    NARCIS (Netherlands)

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

    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

  17. The Jlab Upgrade - Nucleon Studies with CLAS12

    International Nuclear Information System (INIS)

    Volker Burkert

    2007-01-01

    An overview is presented on the program to study the nucleon structure at the 12 GeV Jlab Upgrade using the CLAS12 detector. The focus is on deeply virtual exclusive processes to access the generalized parton distributions, semi-inclusive processes to study transveresx momentum-dependent distributions functions, and inclusive spin structure functions and resonance transition form factors at high Q 2 and with high precision

  18. New ways to access the transverse spin content of the nucleon

    International Nuclear Information System (INIS)

    Beiyad, M El; Pire, B; Szymanowski, L; Wallon, S

    2011-01-01

    We first describe a new way to access the chiral odd transversity parton distribution in the proton through the photoproduction of lepton pairs. The basic ingredient is the interference of the usual Bethe-Heitler or Drell-Yan amplitudes with the amplitude of a process, where the photon couples to quarks through its chiral-odd distribution amplitude, which is normalized to the magnetic susceptibility of the QCD vacuum. We also show how the chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed experimentally through the exclusive electro - or photoproduction process of a meson pair with a large invariant mass and when the final nucleon has a small transverse momentum. We calculate perturbatively the scattering amplitude at leading order, both in the high energy domain which may be accessed in electron-ion colliders and in the medium energy range. Estimated rates are encouraging.

  19. Three-Dimensional parton structure of light nuclei

    Science.gov (United States)

    Scopetta, Sergio; Del Dotto, Alessio; Kaptari, Leonid; Pace, Emanuele; Rinaldi, Matteo; Salmè, Giovanni

    2018-03-01

    Two promising directions beyond inclusive deep inelastic scattering experiments, aimed at unveiling the three dimensional structure of the bound nucleon, are reviewed, considering in particular the 3He nuclear target. The 3D structure in coordinate space can be accessed through deep exclusive processes, whose non-perturbative part is encoded in generalized parton distributions. In this way, the distribution of partons in the transverse plane can be obtained. As an example of a deep exclusive process, coherent deeply virtual Compton scattering off 3He nuclei, important to access the neutron generalized parton distributions (GPDs), will be discussed. In Impulse Approximation (IA), the sum of the two leading twist, quark helicity conserving GPDs of 3He, H and E, at low momentum transfer, turns out to be dominated by the neutron contribution. Besides, a technique, able to take into account the nuclear effects included in the Impulse Approximation analysis, has been developed. The spin dependent GPD \\tilde H of 3He is also found to be largely dominated, at low momentum transfer, by the neutron contribution. The knowledge of the GPDs H,E and \\tilde H of 3He is relevant for the planning of coherent DVCS off 3He measurements. Semi-inclusive deep inelastic scattering processes access the momentum space 3D structure parameterized through transverse momentum dependent parton distributions. A distorted spin-dependent spectral function has been recently introduced for 3He, in a non-relativistic framework, to take care of the final state interaction between the observed pion and the remnant in semi-inclusive deep inelastic electron scattering off transversely polarized 3He. The calculation of the Sivers and Collins single spin asymmetries for 3He, and a straightforward procedure to effectively take into account nuclear dynamics and final state interactions, will be reviewed. The Light-front dynamics generalization of the analysis is also addressed.

  20. J/Ψ production in an equilibrating partonic system

    International Nuclear Information System (INIS)

    Xu, Xiao-Ming

    1999-01-01

    Any color singlet or octet cc-bar pair is created at short distances and then expands to a full size of J/Ψ. Such a dynamical evolution process is included here in calculations for the J/Ψ number distribution as a function of transverse momentum and rapidity in central Au-Au collisions at both RHIC and LHC energies. The cc-bar pairs are produced in the initial collision and in the partonic system during the prethermal and thermal stages through the partonic channels ab → cc-bar[ 2S+1 L J ] and ab → cc-bar[ 2S+1 L J ]x, and then they dissociate in the latter two stages. Dissociation of cc-bar in the medium occurs via two reactions: (a) color singlet cc-bar plus a gluon turns to color octet cc-bar, (b) color octet cc-bar plus a gluon persists as color octet. There are modest yields of cc-bar in the prethermal stage at RHIC energy and through the reactions ab → cc-bar[ 2S+1 L J ] at LHC energy for partons with large average momentum in the prethermal stage at both collider energies and in the thermal stage at LHC energy. Production from the partonic system competes with the suppression of the initial yield in the deconfined medium. Consequently, a bulge within -1.5 < y < 1.5 has been found for the J/Ψ number distribution and the ratio of J/Ψ number distributions for Au-Au collisions to nucleon-nucleon collisions. This bulge is caused by the partonic system and is thus an indicator of a deconfined partonic medium. Based on this result we suggest the rapidity region worth measuring in future experiments at RHIC and LHC to be -3 < y < 3

  1. Nucleon structure functions

    International Nuclear Information System (INIS)

    Virchaux, M.

    1992-11-01

    The present status of experimental measurements of the nucleon structure functions is reviewed. The results from nearly all deep inelastic experiments are in good mutual agreement. Principles of the analysis of these structure function data in the framework of QCD are described. The specific features of the perturbative QCD predictions are observed in the data. This provides quantitative tests of the validity of QCD as well as determinations of the various parton distributions in the nucleon and some of the most precise measurements of the strong coupling constant αs. The future of this field of experimental physics is sketched

  2. Parton self-energies for general momentum-space anisotropy

    Science.gov (United States)

    Kasmaei, Babak S.; Strickland, Michael

    2018-03-01

    We introduce an efficient general method for calculating the self-energies, collective modes, and dispersion relations of quarks and gluons in a momentum-anisotropic high-temperature quark-gluon plasma. The method introduced is applicable to the most general classes of deformed anisotropic momentum distributions and the resulting self-energies are expressed in terms of a series of hypergeometric basis functions which are valid in the entire complex phase-velocity plane. Comparing to direct numerical integration of the self-energies, the proposed method is orders of magnitude faster and provides results with similar or better accuracy. To extend previous studies and demonstrate the application of the proposed method, we present numerical results for the parton self-energies and dispersion relations of partonic collective excitations for the case of an ellipsoidal momentum-space anisotropy. Finally, we also present, for the first time, the gluon unstable mode growth rate for the case of an ellipsoidal momentum-space anisotropy.

  3. Nucleon Spin Structure: Longitudinal and Transverse

    International Nuclear Information System (INIS)

    Chen, Jian-Ping

    2011-01-01

    Inclusive Deep-Inelastic Scattering (DIS) experiments have provided us with the most extensive information on the unpolarized and longitudinal polarized parton (quark and gluon) distributions in the nucleon. It has becoming clear that transverse spin and transverse momentum dependent distributions (TMDs) study are crucial for a more complete understanding of the nucleon structure and the dynamics of the strong interaction. The transverse spin structure and the TMDs are the subject of increasingly intense theoretical and experimental study recently. With a high luminosity electron beam facility, JLab has played a major role in the worldwide effort to study both the longitudinal and transverse spin structure. Highlights of recent results will be presented. With 12-GeV energy upgrade, JLab will provide the most precise measurements in the valence quark region to close a chapter in longitudinal spin study. JLab will also perform a multi-dimensional mapping of the transverse spin structure and TMDs in the valence quark region through Semi-Inclusive DIS (SIDIS) experiments, providing a 3-d partonic picture of the nucleon in momentum space and extracting the u and d quark tensor charges of the nucleon. The precision mapping of TMDs will also allow a detailed study of the quark orbital motion and its dynamics.

  4. 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.

  5. Multi parton interactions and multi parton distributions in QCD

    International Nuclear Information System (INIS)

    Diehl, M.

    2012-01-01

    After a brief recapitulation of the general interest of parton densities, we discuss multiple hard interactions and multi parton distributions. We report on recent theoretical progress in their QCD description, on outstanding conceptual problems and on possibilities to use multi parton distributions as a laboratory to test and improve our understanding of hadron structure. (author)

  6. The QCD coupling and parton distributions at high precision

    International Nuclear Information System (INIS)

    Bluemlein, Johannes

    2010-07-01

    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 α s (M 2 Z ). We also discuss the impact of these quantities on precision observables at hadron colliders. (orig.)

  7. One-particle inclusive processes in deeply inelastic lepton-nucleon scattering

    CERN Document Server

    Graudenz, Dirk

    1994-01-01

    Abstract: The one-particle inclusive cross section in deeply inelastic lepton--nucleon scattering, expressed in terms of parton densities and fragmentation functions being differential in the invariant mass of the observed hadron and of the incoming nucleon, diverges if this invariant mass vanishes. This divergence can be traced back to the kinematical configuration where the parent parton of the observed hadron is emitted collinearly from the incoming parton of the QCD subprocess. By using the concept of ``fracture functions'', which has recently been introduced by Trentadue and Veneziano, it is possible to absorb this divergence in these new distribution functions as long as the observed hadron is not soft. This procedure allows the determination of a finite one-particle inclusive cross section in next-to-leading order QCD perturbation theory. We give details of the calculation and the explicit form of the bare fracture functions in terms of the renormalized ones.

  8. Nucleon Electromagnetic Form Factors

    Energy Technology Data Exchange (ETDEWEB)

    Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi

    2007-10-01

    There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.

  9. From quarks to nucleons in dark matter direct detection

    Science.gov (United States)

    Bishara, Fady; Brod, Joachim; Grinstein, Benjamin; Zupan, Jure

    2017-11-01

    We provide expressions for the nonperturbative matching of the effective field theory describing dark matter interactions with quarks and gluons to the effective theory of nonrelativistic dark matter interacting with nonrelativistic nucleons. We give expressions of leading and subleading order in chiral counting. In general, a single partonic operator matches onto several nonrelativistic operators already at leading order in chiral counting. Keeping only one operator at the time in the nonrelativistic effective theory thus does not properly describe the scattering in direct detection. The matching of the axial-axial partonic level operator, as well as the matching of the operators coupling DM to the QCD anomaly term, include naively momentum suppressed terms. However, these are still of leading chiral order due to pion poles and can be numerically important.

  10. 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.)

  11. Reweighting Parton Showers

    CERN Document Server

    Bellm, Johannes; Richardson, Peter; Siódmok, Andrzej; Webster, Stephen

    2016-01-01

    We report on the possibility of reweighting parton-shower Monte Carlo predictions for scale variations in the parton-shower algorithm. The method is based on a generalization of the Sudakov veto algorithm. We demonstrate the feasibility of this approach using example physical distributions. Implementations are available for both the parton-shower modules in the Herwig 7 event generator.

  12. Once more on the radiative corrections to the nucleon structure functions in QCD

    International Nuclear Information System (INIS)

    Stamenov, D.B.

    1994-09-01

    A new representation of the next to leading QCD corrections to the nucleon structure functions is given in terms of parton distributions. All O(α s ) corrections to the leading logarithmic approximation (LLA) are included. In contrast to the similar representations in the literature terms of order O(α 2 s ) do not attend in our expressions for the nucleon structure functions taken in the next to leading logarithmic approximation. This result is generalized for any order in α s beyond the LLA. Terms of order O(α n s ) which belong only tot he approximation in consideration are present in such a representation for the structure functions. (author). 11 refs

  13. Revealing Partons in Hadrons: From the ISR to the SPS Collider

    CERN Document Server

    Darriulat, Pierre

    2015-01-01

    Our understanding of the structure of hadrons has developed during the seventies and early eighties from a few vague ideas to a precise theory, Quantum Chromodynamics, that describes hadrons as made of elementary partons (quarks and gluons). Deep inelastic scattering of electrons and neutrinos on nucleons and electron–positron collisions have played a major role in this development. Less well known is the role played by hadron collisions in revealing the parton structure, studying the dynamic of interactions between partons and offering an exclusive laboratory for the direct study of gluon interactions. The present article recalls the decisive contributions made by the CERN Intersecting Storage Rings and, later, the proton–antiproton SPS Collider to this chapter of physics.

  14. Results on nucleon structure functions in quantum chromodynamics

    International Nuclear Information System (INIS)

    Martin, F.

    1979-01-01

    Gluon bremsstrahlung processes inside the nucleon are investigated using the standard renormalization-group analysis. A new method of inverting the moments is applied which leads to analytic results for the parton distributions near x = 1 and x = 0. The nucleon is considered as a bound state of three quarks subsequently ''renormalized'' by gluon bremsstrahlung and quark-antiquark pair production. An ''unrenormalized'' valance quark distribution peaked at x = 1/3, with a width related to the nucleon radius, leads to good agreement with deep-inelastic data. However, the gluon distribution obtained seems too steep near x = 0

  15. Spin structure at the partonic level. Pt. 2

    International Nuclear Information System (INIS)

    Leader, E.

    1983-01-01

    Knowledge of the spin and momentum distribution of partons inside a polarised nucleon, as deduced from lepton scattering, is combined with lowest order QCD to calculate spin dependent parameters in large psub(T) hadronic reactions. Clear predictions emerge in some cases and are in conflict with present experimental results. There is a real challenge to improve both theory and experiment. (orig.)

  16. Clan properties in parton showers

    International Nuclear Information System (INIS)

    Ugoccioni, R.; Giovannini, A.; Lupia, S.

    1994-01-01

    By considering clans as genuine elementary sub-processes, i.e., intermediate parton sources in the Simplified Parton Shower model, a generalized version of this model is defined. It predicts analytically clan properties at parton level in agreement with the general trends observed experimentally at hadronic level and in Monte Carlo simulations both at partonic and hadronic level. In particular the model shows a linear rising in rapidity of the average number of clans at fixed energy of the initial parton and its subsequent bending for rapidity intervals at the border of phase space, and approximate energy independence of the average number of clans in fixed rapidity intervals. The energy independence becomes stricter by properly normalizing the average number of clans (orig.)

  17. Clan properties in parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Ugoccioni, R. (Dipt. di Fisica Teorica, Univ. di Torino (Italy) INFN (Italy)); Giovannini, A. (Dipt. di Fisica Teorica, Univ. di Torino (Italy) INFN (Italy)); Lupia, S. (Dipt. di Fisica Teorica, Univ. di Torino (Italy) INFN (Italy))

    1994-11-01

    By considering clans as genuine elementary sub-processes, i.e., intermediate parton sources in the Simplified Parton Shower model, a generalized version of this model is defined. It predicts analytically clan properties at parton level in agreement with the general trends observed experimentally at hadronic level and in Monte Carlo simulations both at partonic and hadronic level. In particular the model shows a linear rising in rapidity of the average number of clans at fixed energy of the initial parton and its subsequent bending for rapidity intervals at the border of phase space, and approximate energy independence of the average number of clans in fixed rapidity intervals. The energy independence becomes stricter by properly normalizing the average number of clans (orig.)

  18. Unbiased determination of polarized parton distributions and their uncertainties

    CERN Document Server

    Ball, Richard D.; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

    2013-01-01

    We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, ...

  19. Internal spin structure of the nucleon

    International Nuclear Information System (INIS)

    Hughes, V.W.; Kuti, J.

    1983-01-01

    The study of the structure of the proton and neutron through deep inelastic scattering, initially with electrons but subsequently with muons and neutrinos as well, has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD). One important aspect of these theoretical and experimental developments is the two spin-dependent structure functions, which are independent of the two spin-averaged structure functions and define the internal spin structure of the nucleon. Since both quarks and gluons possess spin and the forces between them are spin dependent, we can expect important information on these forces and on nucleon structure to be obtained through the study of the spindependent aspects of the nucleon wave function, as has been the case before in atomic and nuclear physics

  20. EXPLORING THE POLARIZATION OF GLUONS IN THE NUCLEON.

    Energy Technology Data Exchange (ETDEWEB)

    STRATMANN,M.; VOGELSANG,W.

    2007-10-22

    We give an overview of the current status of investigations of the polarization of gluons in the nucleon. We describe some of the physics of the spin-dependent gluon parton distribution and its phenomenology in high-energy polarized hadronic scattering. We also review the recent experimental results.

  1. The spin structure of the nucleon

    International Nuclear Information System (INIS)

    Deur, A.

    2008-02-01

    This document describes the recent experimental results on the spin structure of the nucleon obtained with the electron accelerator Thomas Jefferson National Facility (Jefferson Lab), Virginia. We first discuss the goal of studying the nucleon spin structure and give the basis and phenomenology of high energy lepton scattering. Then, we discuss with some details a few sum rules concerning the spin structure of the nucleon. Those are important tools for studying the nucleon spin structure at Jefferson Lab. We then describe the present experimental situation and analyze the results. We have been able to determine an effective coupling constant for the strong interaction for any regime of quantum chromodynamics which proves that QCD is an approximately conformal theory. We conclude on the perspectives for this field of research, in particular with the 12 GeV energy upgrade of Jefferson Lab. The top priority will be the measurement of generalised parton distributions. The only issue that will stay misunderstood is the role of the very low x domain on the spin structure of the nucleon

  2. The problem of nucleon production in the quark parton model

    International Nuclear Information System (INIS)

    Ranft, J.; Ranft, G.

    1977-06-01

    Quark fragmentation into hadrons, esp. nucleons, is studied fitting empirical fragmentation functions to e + e - annihilation data. We find fragmentation functions deviating from counting rule predictions as well as from scaling due to the threshold in kaon and nucleon production. Using these fragmentation functions we study particle production ratios in ep and large transverse momentum hadronic reactions. In both cases we find the ratios p/π + and antip/π - to agree roughly in magnitude with the measured ratios. The model is however inconsistent with the transverse momentum -12 behaviour of large transverse momentum proton spectra. (author)

  3. Spin structure of the nucleon and polarization

    International Nuclear Information System (INIS)

    Prescott, C.Y.

    1994-09-01

    Recent experiments at CERN and SLAC have added new knowledge about the spin structure of the proton and the deuteron. A brief historical background is presented, the status of experiments is discussed, and progress in the understanding of the spin of the nucleon in the context of the quark parton model is summarized

  4. 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.

  5. 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.

  6. Proton-antiproton annihilation into a lambdaC-antiLambdaC pair within the generalized parton picture

    International Nuclear Information System (INIS)

    Goritschnig, A. T.

    2009-01-01

    The proton-antiproton annihilation into a LambdaC-AntiLambdaC pair is investigated within the handbag approach. It is shown that the dominant dynamical mechanism, characterized by the partonic subprocess anti-u u -> anti-c c, factorizes in the sense that only the subprocess contains highly virtual partons, a gluon to lowest order of perturbative QCD, while the hadronic matrix elements embody only soft scales and can be parameterized in terms of helicity flip and non-flip generalized parton distributions. Modelling these parton distributions by overlaps of light-cone wave functions for the involved baryons were able to predict cross sections and spin correlation parameters for the process of interest. (author) [de

  7. Spin effects in elastic scattering of nucleons and new approach to problem of account for spin structure of hadrons

    International Nuclear Information System (INIS)

    Babaev, Z.R.; Shchelkachev, A.V.

    1991-01-01

    Prospects of decribing polarization effects within the framework of quark-parton models (QPM) using a density matrix in order to describe the parton spin states in hadrons are discussed. Such an approach allows one to get rid of contradictions occuring when describing the QPM of reactions of hadrons polarized in perpendicular to the scattering plane in case of applying spin distribution functions. Different model predictions for the observed one- and two-spin correlations in elastic nucleon-nucleon scattering are analyzed. 12 refs., 2 tabs

  8. Deep inelastic processes. Phenomenology. Quark-parton model

    International Nuclear Information System (INIS)

    Ioffe, B.L.; Lipatov, L.N.; Khoze, V.A.

    1983-01-01

    Main theoretical approaches and experimental results related to deep inelastic processes are systematically outlined: electroproduction, neutrino scattering on nucleon, electron-positron pairs annihilation into hadron γγ collisions, production of lepton pairs in hadron collisions with a large effective mass or hadrons with large transverse momenta. Kinematics and phenomenology, space-time description of deep inelastic processes, sum rules, parton and quark-parton models are considered. The experiment is briefly discussed in the book. It is performed from the stand point of comparing it with the theory, experimental data are given as of June, 1982. Since the time of accomplishing the study on the manuscript a number of new experimental results not changing however the statements made in the book appeared. Principal consists in experiments with colliding proton-antiproton beams in CERN, which resulted in discovery of intermediate W-bozon

  9. Global study of nuclear modifications on parton distribution functions

    Directory of Open Access Journals (Sweden)

    Rong Wang

    2017-07-01

    Full Text Available 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 parameters from the global analysis, the nuclear modifications of parton distribution functions of unmeasured nuclei can be predicted in our model. Nuclear modification of deuteron is also predicted and shown with recent measurement at JLab.

  10. Parton degrees of freedom from the path-integral formalism

    International Nuclear Information System (INIS)

    Liu, Keh-Fei

    2000-01-01

    We formulate the hadronic tensor W μν of deep inelastic scattering in the path-integral formalism. It is shown that there are 3 gauge invariant and topologically distinct contributions. In addition to the valence contribution, there are two sources for the sea--one in the connected insertion and the other in the disconnected insertion. The operator product expansion is carried out in this formalism. The operator rescaling and mixing reveal that the connected sea partons evolve the same way as the valence; i.e., their evolution is decoupled from the disconnected sea and the gluon distribution functions. We explore the phenomenological consequences of this classification in terms of the small x behavior, Gottfried sum rule violation, and flavor dependence. In particular, we point out that in the nucleon u(bar sign) and d(bar sign) partons have both connected and disconnected sea contributions, whereas the s(bar sign) parton has only the disconnected sea contribution. This difference between u(bar sign)+d(bar sign) and s(bar sign), as far as we know, has not been taken into account in the fitting of parton distribution functions to experiments. (c) 2000 The American Physical Society

  11. A determination of parton distributions with faithful uncertainty estimation

    International Nuclear Information System (INIS)

    Ball, Richard D.; Del Debbio, Luigi; Forte, Stefano; Guffanti, Alberto; Latorre, Jose I.; Piccione, Andrea; Rojo, Juan; Ubiali, Maria

    2009-01-01

    We present the determination of a set of parton distributions of the nucleon, at next-to-leading order, from a global set of deep-inelastic scattering data: NNPDF1.0. The determination is based on a Monte Carlo approach, with neural networks used as unbiased interpolants. This method, previously discussed by us and applied to a determination of the nonsinglet quark distribution, is designed to provide a faithful and statistically sound representation of the uncertainty on parton distributions. We discuss our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the evolution equations and its benchmarking, and the method used to compute physical observables. We discuss the parametrization and fitting of neural networks, and the algorithm used to determine the optimal fit. We finally present our set of parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent parton sets. We use it to compute the benchmark W and Z cross sections at the LHC. We discuss issues of delivery and interfacing to commonly used packages such as LHAPDF

  12. Nucleon-nucleon correlations in dense nuclear matter

    International Nuclear Information System (INIS)

    Alm, T.

    1993-02-01

    In this thesis new results on the problematics of the formation of nucleon-nucleon correlations in nuclear matter could be presented. Starting from a general study of the two-particle problem in matter we studied the occurrence of a suprafluid phase (pair condensate of nucleons). The Gorkov decoupling by means of anomalous Green functions was generalized, so that also Cooper pairs with spin 1 (triplet pairing) can be described. A generalized gap equation resulted, which permits to determine the order parameters of the suprafluied phase in arbitrary channels of the nucleon-nucleon scattering states. This equation was solvd in the 1 S 0 -, in the 3 P 2 - 3 F 2 , and in the 3 S 1 - 3 D 1 channel under application of realistic nucleon-nucleon potentials. The behaviour of the resulting gap parameters in the single channels was studied as function of density and temperature. (orig.) [de

  13. Measurement of exclusive π(0) electroproduction structure functions and their relationship to transverse generalized parton distributions.

    Science.gov (United States)

    Bedlinskiy, I; Kubarovsky, V; Niccolai, S; Stoler, P; Adhikari, K P; Aghasyan, M; Amaryan, M J; Anghinolfi, M; Avakian, H; Baghdasaryan, H; Ball, J; Baltzell, N A; Battaglieri, M; Bennett, R P; Biselli, A S; Bookwalter, C; Boiarinov, S; Briscoe, W J; Brooks, W K; Burkert, V D; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Contalbrigo, M; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Fleming, J A; Forest, T A; Fradi, A; Garçon, M; Gevorgyan, N; Giovanetti, K L; Girod, F X; Gohn, W; Gothe, R W; Graham, L; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Heddle, D; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, F J; Koirala, S; Kubarovsky, A; Kuhn, S E; Kuleshov, S V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I J D; Mao, Y; Markov, N; Martinez, D; Mayer, M; McKinnon, B; Meyer, C A; Mineeva, T; Mirazita, M; Mokeev, V; Moutarde, H; Munevar, E; Munoz Camacho, C; Nadel-Turonski, P; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Pappalardo, L L; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Phelps, E; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Puckett, A J R; Raue, B A; Ricco, G; Rimal, D; Ripani, M; Rosner, G; Rossi, P; Sabatié, F; Saini, M S; Salgado, C; Saylor, N; Schott, D; Schumacher, R A; Seder, E; Seraydaryan, H; Sharabian, Y G; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tian, Ye; Tkachenko, S; Ungaro, M; Vineyard, M F; Vlassov, A; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Weinstein, L B; Weygand, D P; Wood, M H; Zachariou, N; Zhang, J; Zhao, Z W; Zonta, I

    2012-09-14

    Exclusive π(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 ϕ(π), 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 σ(T)+ϵσ(L), σ(TT), and σ(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 generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates σ(T)+ϵσ(L) and fails to account for σ(TT) and σ(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 nonflip processes. The results confirm that exclusive π(0) electroproduction offers direct experimental access to the transversity GPDs.

  14. Measurement of Exclusive π0 Electroproduction Structure Functions and their Relationship to Transverse Generalized Parton Distributions

    Science.gov (United States)

    Bedlinskiy, I.; Kubarovsky, V.; Niccolai, S.; Stoler, P.; Adhikari, K. P.; Aghasyan, M.; Amaryan, M. J.; Anghinolfi, M.; Avakian, H.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bennett, R. P.; Biselli, A. S.; Bookwalter, C.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Forest, T. A.; Fradi, A.; Garçon, M.; Gevorgyan, N.; Giovanetti, K. L.; Girod, F. X.; Gohn, W.; Gothe, R. W.; Graham, L.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Heddle, D.; Hicks, K.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kuhn, S. E.; Kuleshov, S. V.; Kvaltine, N. D.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mao, Y.; Markov, N.; Martinez, D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moutarde, H.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Anefalos Pereira, S.; Phelps, E.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Ricco, G.; Rimal, D.; Ripani, M.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Saylor, N.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Vineyard, M. F.; Vlassov, A.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2012-09-01

    Exclusive π0 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 Q2, xB, t, and ϕπ, in the Q2 range from 1.0 to 4.6GeV2, -t up to 2GeV2, and xB from 0.1 to 0.58. Structure functions σT+ɛσL, σTT, and σLT were extracted as functions of t for each of 17 combinations of Q2 and xB. The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates σT+ɛσL and fails to account for σTT and σLT, 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 nonflip processes. The results confirm that exclusive π0 electroproduction offers direct experimental access to the transversity GPDs.

  15. Longitudinal-Transverse Separation of Deep-Inelastic Scattering at Low Q² on Nucleons and Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Tvaskis, Vladas [Vrije Univ., Amsterdam (Netherlands)

    2004-12-06

    Since the early experiments at SLAC, which discovered the nucleon substructure and led to the development of the quark parton model, deep inelastic scattering (DIS) has been the most powerful tool to investigate the partonic substructure of the nucleon. After about 30 years of experiments with electron and muon beams the nucleon structure function F2(x,Q2) is known with high precision over about four orders of magnitude in x and Q2. In the region of Q2 > 1 (GeV/c)2 the results of the DIS measurements are interpreted in terms of partons (quarks and gluons). The theoretical framework is provided in this case by perturbative Quantum Chromo Dynamics (pQCD), which includes scaling violations, as described by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations. The description starts to fail when Q2 becomes of the order of 1 (GeV/c)2, where non-perturbative effects (higher-twist effects), which are still not fully understood, become important (non-pQCD). The sensitivity for order-n twist effects increases with decreasing Q2, since they include a factor 1/(Q2n) (n ≥ 1).

  16. Strange quark distribution and parton charge symmetry violation in a semi-inclusive process

    International Nuclear Information System (INIS)

    Kitagawa, Hisashi; Sakemi, Yasuhiro

    2000-01-01

    It is possible to observe a semi-inclusive reaction with tagged charged kaons using the RICH detector at DESY-HERA. Using the semi-inclusive process we study two kinds of parton properties in the nucleon. We study relations between cross sections and strange quark distributions, which are expected to be measured more precisely in such a process than in the process in which pions are tagged. We also investigate charge symmetry violation (CSV) in the nucleon, which appears in the region x ≤ 0.1. (author)

  17. Charge symmetry breaking in parton distribution functions from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Tsukuba Univ., Ibaraki (Japan). Center for Computational Sciences; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (Germany); Thomas, A.W.; Young, R.D. [Adelaide Univ. SA (Australia). School of Physics and Chemistry; Winter, F. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik

    2010-12-15

    By determining the quark momentum fractions of the octet baryons from N{sub f}=2+1 lattice simulations, we are able to predict the degree of charge symmetry violation in the parton distribution functions of the nucleon. This is of importance, not only as a probe of our understanding of the non-perturbative structure of the proton but also because such a violation constrains the accuracy of global ts to parton distribution functions and hence the accuracy with which, for example, cross sections at the LHC can be predicted. A violation of charge symmetry may also be critical in cases where symmetries are used to guide the search for physics beyond the Standard Model. (orig.)

  18. Charge symmetry breaking in parton distribution functions from lattice QCD

    International Nuclear Information System (INIS)

    Horsley, R.; Zanotti, J.M.; Rakow, P.E.L.; Stueben, H.; Thomas, A.W.; Young, R.D.; Winter, F.; Regensburg Univ.

    2010-12-01

    By determining the quark momentum fractions of the octet baryons from N f =2+1 lattice simulations, we are able to predict the degree of charge symmetry violation in the parton distribution functions of the nucleon. This is of importance, not only as a probe of our understanding of the non-perturbative structure of the proton but also because such a violation constrains the accuracy of global ts to parton distribution functions and hence the accuracy with which, for example, cross sections at the LHC can be predicted. A violation of charge symmetry may also be critical in cases where symmetries are used to guide the search for physics beyond the Standard Model. (orig.)

  19. 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...

  20. Fermi-Dirac statistics plus liquid description of quark partons

    International Nuclear Information System (INIS)

    Buccella, F.; Migliore, G.; Tibullo, V.

    1995-01-01

    A previous approach with Fermi-Dirac distributions for fermion partons is here improved to comply with the expected low x behaviour of structure functions. We are so able to get a fair description of the unpolarized and polarized structure functions of the nucleons as well as of neutrino data. We cannot reach definite conclusions, but confirm our suspicion of a relationship between the defects in Gottfried and spin sum rules. (orig.)

  1. CT14 intrinsic charm parton distribution functions from CTEQ-TEA global analysis

    Science.gov (United States)

    Hou, Tie-Jiun; Dulat, Sayipjamal; Gao, Jun; Guzzi, Marco; Huston, Joey; Nadolsky, Pavel; Schmidt, Carl; Winter, Jan; Xie, Keping; Yuan, C.-P.

    2018-02-01

    We investigate the possibility of a (sizable) nonperturbative contribution to the charm parton distribution function (PDF) in a nucleon, theoretical issues arising in its interpretation, and its potential impact on LHC scattering processes. The "fitted charm" PDF obtained in various QCD analyses contains a process-dependent component that is partly traced to power-suppressed radiative contributions in DIS and is generally different at the LHC. We discuss separation of the universal component of the nonperturbative charm from the rest of the radiative contributions and estimate its magnitude in the CT14 global QCD analysis at the next-to-next-to leading order in the QCD coupling strength, including the latest experimental data from HERA and the Large Hadron Collider. Models for the nonperturbative charm PDF are examined as a function of the charm quark mass and other parameters. The prospects for testing these models in the associated production of a Z boson and a charm jet at the LHC are studied under realistic assumptions, including effects of the final-state parton showering.

  2. Transverse momentum distributions inside the nucleon from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Musch, Bernhard Ulrich

    2009-05-29

    Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)

  3. Unbiased determination of polarized parton distributions and their uncertainties

    Energy Technology Data Exchange (ETDEWEB)

    Ball, Richard D. [Tait Institute, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh EH9 3JZ, Scotland (United Kingdom); Forte, Stefano, E-mail: forte@mi.infn.it [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Guffanti, Alberto [The Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Nocera, Emanuele R. [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Genova (Italy); Rojo, Juan [PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland)

    2013-09-01

    We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations.

  4. Unbiased determination of polarized parton distributions and their uncertainties

    International Nuclear Information System (INIS)

    Ball, Richard D.; Forte, Stefano; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

    2013-01-01

    We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations

  5. Nuclear and partonic dynamics in high energy elastic nucleus-nucleus scattering

    International Nuclear Information System (INIS)

    Malecki, A.

    1991-01-01

    A hybrid description of diffraction which combines a geometrical modelling of multiple scattering with many-channel effects resulting from intrinsic dynamics on nuclear and sub-nuclear level is presented. The application to the 4 He- 4 He elastic scattering is very satisfactory. Our analysis suggests that at large momentum transfers the parton constituents of nucleons immersed in nuclei are deconfined. (author)

  6. ABM11 parton distributions and benchmarks

    International Nuclear Information System (INIS)

    Alekhin, Sergey; Bluemlein, Johannes; Moch, Sven-Olaf

    2012-08-01

    We present a determination of the nucleon parton distribution functions (PDFs) and of the strong coupling constant α 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 f =3,4,5 and uses the MS scheme for α 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.

  7. 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.

  8. A Lattice Calculation of Parton Distributions

    International Nuclear Information System (INIS)

    Alexandrou, Constantia; Cichy, Krzysztof; Poznan Univ.; Drach, Vincent; Univ. of Southern Denmark, Odense; Garcia-Ramos, Elena; Humboldt-Universitaet, Berlin; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian

    2015-04-01

    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 N 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.

  9. General operator form of the non-local three-nucleon force

    Energy Technology Data Exchange (ETDEWEB)

    Topolnicki, K. [Jagiellonian University, M. Smoluchowski Institute of Physics, Krakow (Poland)

    2017-09-15

    This paper describes a procedure to obtain the general form of the three-nucleon force. The result is an operator form where the momentum space matrix element of the three-nucleon potential is written as a linear combination of 320 isospin-spin-momentum operators and scalar functions of momenta. Any spatial and isospin rotation invariant three-nucleon force can be written in this way and in order for the potential to be Hermitian, symmetric under parity inversion, time reversal and particle exchange, the scalar functions must have definite transformation properties under these discrete operations. A complete list of the isospin-spin-momentum operators and scalar function transformation properties is given. (orig.)

  10. Transverse Momentum Dependent Parton Distribution/Fragmentation Functions at an Electron-Ion Collider

    International Nuclear Information System (INIS)

    Anselmino, M.; Avakian, H.; Boer, D.; 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, P.; Soffer, J.; Sulkosky, V.; Wang, Y.; 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 correlation functions, were discussed extensively at the Duke workshop. In this paper, we summarize first the theoretical issues concerning the study of partonic structure of hadrons at a future electron-ion collider (EIC) with emphasis on the TMDs. We then present simulation results on experimental studies of TMDs through measurements of single spin asymmetries (SSA) from semi-inclusive deep-inelastic scattering (SIDIS) processes with an EIC, and discuss the requirement of the detector for SIDIS measurements. The dynamics of parton correlations in the nucleon is further explored via a study of SSA in D ((bar D)) production at large transverse momenta with the aim of accessing the unexplored tri-gluon correlation functions. The workshop participants identified the SSA measurements in SIDIS as a golden program to study TMDs in both the sea and valence quark regions and to study the role of gluons, with the Sivers asymmetry measurements as examples. Such measurements will lead to major advancement in our understanding of TMDs in the valence quark region, and more importantly also allow for the investigation of TMDs in the sea quark region along with a study of their evolution.

  11. Correlations in double parton distributions: perturbative and non-perturbative effects

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi, Matteo; Scopetta, Sergio [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia andIstituto Nazionale di Fisica Nucleare, Sezione di Perugia, via A. Pascoli, I-06123 Perugia (Italy); Traini, Marco [Institut de Physique Théorique CEA-Saclay, F-91191 Gif-sur-Yvette (France); INFN - TIFPA, Dipartimento di Fisica, Università degli Studi di Trento,Via Sommarive 14, I-38123 Povo (Trento) (Italy); Vento, Vicente [Departament de Física Teòrica, Universitat de València and Institut de Física Corpuscular,Consejo Superior de Investigaciones Científicas, 46100 Carrer del Dr. Moliner 50 València (Spain)

    2016-10-12

    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 Poincaré 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, finding that, in some cases, they are strongly suppressed at low longitudinal momenta, while for other distributions they can be sizeable. For example, the effect of gluon-gluon correlations can be as large as 20 %. We have shown that these behaviors can be understood in terms of a delicate interference of non-perturbative correlations, generated by the dynamics of the model, and perturbative ones, generated by the model independent evolution procedure. Our analysis shows that at LHC kinematics two-parton correlations can be relevant in DPS, and therefore we address the possibility to study them experimentally.

  12. Orbital angular momentum parton distributions in quark models

    International Nuclear Information System (INIS)

    Scopetta, S.; Vento, V.

    2000-01-01

    At the low energy, hadronic, scale we calculate Orbital Angular Momentum (OAM) twist-two parton distributions for the relativistic MIT bag model and for nonrelativistic quark models. We reach the scale of the data by leading order evolution in perturbative QCD. We confirm that the contribution of quarks and gluons OAM to the nucleon spin grows with Q 2 , and it can be relevant at the experimental scale, even if it is negligible at the hadronic scale, irrespective of the model used. The sign and shape of the quark OAM distribution at high Q 2 may depend strongly on the relative size of the OAM and spin distributions at the hadronic scale. Sizeable quark OAM distributions at the hadronic scale, as proposed by several authors, can produce the dominant contribution to the nucleon spin at high Q 2 . (author)

  13. Constituent quarks and the gluonic contribution to the spin of the nucleon

    International Nuclear Information System (INIS)

    Eldahoumi, Gamal

    2009-01-01

    The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)

  14. Constituent quarks and the gluonic contribution to the spin of the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Eldahoumi, Gamal

    2009-01-15

    The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)

  15. The gluon contribution to polarised nucleon structure functions

    International Nuclear Information System (INIS)

    Ross, G.G.; Roberts, R.G.

    1990-08-01

    As with all parton distributions in quantum chromodynamics (QCD) the separation of polarised nucleon structure functions into gluon and quark contributions must be specified. We consider a definition of the gluon contribution to polarised nucleon structure functions based on exclusive processes which is explicitly gauge invariant, has no regularisation ambiguities, is insensitive to infrared singularities and can be related to other polarised scattering processes. We discuss the relationship of this gluon definition to others that have recently been used and to the estimates that have been made of the gluon contribution using current algebra and other methods. A quantitative analysis of the structure function g 1 (x,Q 2 ) for polarised deep inelastic scattering is carried out, with the aim of examining the importance of the gluon contribution. Using the positivity of parton distributions the magnitude of Δg(x,Q 2 ) is constrained by a realistic estimate of the unpolarised glue. With the appropriate choice of the hard scattering cross-section, Δσ γg , we find that even with a maximally polarised glue (for x > 0.1), some polarised strange quark contribution is still needed by the data of the EMC. (author)

  16. General aspects of the nucleon-nucleon interaction and nuclear matter properties

    Energy Technology Data Exchange (ETDEWEB)

    Plohl, Oliver

    2008-07-25

    The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are

  17. General aspects of the nucleon-nucleon interaction and nuclear matter properties

    International Nuclear Information System (INIS)

    Plohl, Oliver

    2008-01-01

    The subject of the present thesis is at first the investigation of model independent properties of the nucleon-nucleon (NN) interaction in the vacuum concerning the relativistic structure and the implications for nuclear matter properties. Relativistic and non-relativistic meson-exchange potentials, phenomenological potentials s well as potentials based on effective field theory (EFT) are therefore mapped on a relativistic operator basis given by the Clifford Algebra. This allows to compare the various approaches at the level of covariant amplitudes where a remarkable agreement is found. Furthermore, the relativistic self-energy is determined in the Hartree-Fock (HF) approximation. The appearance of a scalar and vector field of several hundred MeV magnitude is a general feature of relativistic descriptions of nuclear matter. Within QCD sum rules these fields arise due to the density dependence of chiral condensates. We find that independent of the applied NN interaction large scalar and vector fields are generated when the symmetries of the Lorentz group are restored. In the framework of chiral EFT (chEFT) it is shown, that these fields are generated by short-range next-to-leading order (NLO) contact terms, which are connected to the spin-orbit interaction. To estimate the effect arising from NN correlations the equation of state of nuclear and neutron matter is calculated in the Brueckner-HF (BHF) approximation applying chEFT. Although, as expected, a clear over-binding is found (at NLO a saturating behavior is observed), the symmetry energy shows realistic properties when compared to phenomenological potentials (within the same approximation) and other approaches. The investigation of the pion mass dependence within chEFT at NLO shows that the magnitude of the scalar and vector fields persists in the chiral limit - nuclear matter is still bound. In contrast to the case of a pion mass larger than the physical one the binding energy and saturation density are

  18. Parton distribution functions in the context of parton showers

    International Nuclear Information System (INIS)

    Nagy, Zoltán; Soper, Davison E.

    2014-01-01

    When the initial state evolution of a parton shower is organized according to the standard “backward evolution” prescription, ratios of parton distribution functions appear in the splitting probabilities. The shower thus organized evolves from a hard scale to a soft cutoff scale. At the end of the shower, one expects that only the parton distributions at the soft scale should affect the results. The other effects of the parton distributions should have cancelled. This means that the kernels for parton evolution should be related to the shower splitting functions. If the initial state partons can have non-zero masses, this requires that the evolution kernels cannot be the usual (MS)-bar kernels. We work out what the parton evolution kernels should be to match the shower evolution contained in the parton shower event generator DEDUCTOR, in which the b and c quarks have non-zero masses.

  19. Phenomenology of the neutral weak current in elastic neutrino-nucleon scattering

    International Nuclear Information System (INIS)

    Cochard, G.M.; Ichola, A.

    1978-01-01

    The aim of this study is to check if we can construct the neutral weak current Jsub(μ)sup(nucleonc) of nucleons from ''known'' phenomenological currents, namely electromagnetic Vsub(μ)sup((deg)), Vsub(μ)sup((3)) and charged weak Vsub(μ)sup((+)), Vsub(μ)sup((-)). It will be seen that a neutral weak current, built with these pieces, is valid with respect to the experimental data on elastic neutrino-nucleon scattering through neutral current. The use of these data is interesting in the sense that we can avoid the uncertainties of the quark parton model and the gauge theories prejudices

  20. Updated lattice results for parton distributions

    International Nuclear Information System (INIS)

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

    2017-07-01

    We provide an 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 the one of the phenomenological parameterizations, a feature that makes this approach very promising. 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, which is essential for the prospects of a reliable extraction of the PDFs in the future.

  1. Updated lattice results for 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; Poznan Univ. (Poland). Faculty of Physics; Constantinou, Martha [Temple Univ., Philadelphia, PA (United States); 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

    2017-07-15

    We provide an 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 the one of the phenomenological parameterizations, a feature that makes this approach very promising. 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, which is essential for the prospects of a reliable extraction of the PDFs in the future.

  2. 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.)

  3. 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

  4. Quasi parton distributions and the gradient flow

    International Nuclear Information System (INIS)

    Monahan, Christopher; Orginos, Kostas

    2017-01-01

    We propose a new approach to determining quasi parton distribution functions (PDFs) from lattice quantum chromodynamics. By incorporating the gradient flow, this method guarantees that the lattice quasi PDFs are finite in the continuum limit and evades the thorny, and as yet unresolved, issue of the renormalization of quasi PDFs on the lattice. In the limit that the flow time is much smaller than the length scale set by the nucleon momentum, the moments of the smeared quasi PDF are proportional to those of the lightfront PDF. Finally, we use this relation to derive evolution equations for the matching kernel that relates the smeared quasi PDF and the light-front PDF.

  5. Relativistic generalizations of simple pion-nucleon models

    International Nuclear Information System (INIS)

    McLeod, R.J.; Ernst, D.J.

    1981-01-01

    A relativistic, partial wave N/D dispersion theory is developed for low energy pion-nucleon elastic scattering. The theory is simplified by treating crossing symmetry only to lowest order in the inverse nucleon mass. The coupling of elastic scattering to inelastic channels is included by taking the necessary inelasticity from experimental data. Three models are examined: pseudoscalar coupling of pions and nucleons, pseudovector coupling, and a model in which all intermediate antinucleons are projected out of the amplitude. The phase shifts in the dominant P 33 channel are quantitatively reproduced for P/sub lab/ 33 phase shifts. Thus a model of the pion-nucleon interaction which does not include antinucleon degrees of freedom is found to be unphysical

  6. The spin structure of the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Le Goff, J.M

    2005-02-15

    The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*{delta}{sigma} + {delta}g + L{sub q} + L{sub g} where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L{sub q} and L{sub g} are the orbital momentum of the quark and the gluon respectively. The {delta}{sigma} contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization {delta}g/g and the so-called transversity. (A.C.)

  7. The spin structure of the nucleon

    International Nuclear Information System (INIS)

    Le Goff, J.M.

    2005-02-01

    The nucleon is a spin 1/2 particle. This spin can be decomposed into the contributions of its constituents: 1/2 equals 1/2*ΔΣ + Δg + L q + L g where the first term is the contribution from the spin of the quarks, the second term is the contribution from the spin of the gluons and L q and L g are the orbital momentum of the quark and the gluon respectively. The ΔΣ contribution of the spin of quarks can be studied through polarized deep inelastic scattering (DIS). We introduce DIS and the so-called parton model and then turn to the case of polarized DIS in the inclusive and semi-inclusive cases. We also discuss how a third parton distribution, called transversity, appears together with the unpolarized and the longitudinally polarized (or helicity) ones. We show how the longitudinally polarized gluon distribution can be measured. Then we focus on the SMC and COMPASS experiments performed at CERN. SMC confirmed a previous result by showing that the contribution of the spin of the quark to the spin of the nucleon was small. SMC also performed a measurement on the deuterium in order to test, for the first time, the Bjorker sum rules, which is a fundamental prediction of quantum chromodynamics. The COMPASS experiment started collecting data in 2002. Its main objectives are the gluon polarization Δg/g and the so-called transversity. (A.C.)

  8. The Adler sum rule and quark parton distribution functions in nucleon

    International Nuclear Information System (INIS)

    Niegawa, Akira; Sasaki, Ken.

    1975-01-01

    The behaviour of the quark parton distribution functions is discussed through the phenomenological analysis of the deep inelastic e-p and e-n data under constraint of the saturation of the Adler sum rule. It is concluded that in the region 0 0 where the Regge parametrization can be applied, anti u(x) is equal to anti d(x), and both behave as const/x, (x 0 will be 0.04--0.05); for x 0 x 0 is given. The rate of convergence of the Adler sum rule is also discussed. (auth.)

  9. A new form for the nucleon-nucleon potential

    International Nuclear Information System (INIS)

    Agarwal, B.K.

    1976-01-01

    The form of the internucleon force is considered. It is assumed that the nucleon-nucleon potential depends, in general, both on the distance ν and the angle theta. It is also assumed that the potential V(ν,ω) admits an analytic continuation into the complex ω-plane so that when ω=costheta is real it denotes the direction in which the potential is being determined. The analysis leads to a new parametryzation of the nucleon-nucleon potential

  10. Nonpointlike-parton model with asymptotic scaling and with scaling violationat moderate Q2 values

    International Nuclear Information System (INIS)

    Chen, C.K.

    1981-01-01

    A nonpointlike-parton model is formulated on the basis of the assumption of energy-independent total cross sections of partons and the current-algebra sum rules. No specific strong-interaction Lagrangian density is introduced in this approach. This model predicts asymptotic scaling for the inelastic structure functions of nucleons on the one hand and scaling violation at moderate Q 2 values on the other hand. The predicted scaling-violation patterns at moderate Q 2 values are consistent with the observed scaling-violation patterns. A numerical fit of F 2 functions is performed in order to demonstrate that the predicted scaling-violation patterns of this model at moderate Q 2 values fit the data, and to see how the predicted asymptotic scaling behavior sets in at various x values. Explicit analytic forms of F 2 functions are obtained from this numerical fit, and are compared in detail with the analytic forms of F 2 functions obtained from the numerical fit of the quantum-chromodynamics (QCD) parton model. This comparison shows that this nonpointlike-parton model fits the data better than the QCD parton model, especially at large and small x values. Nachtman moments are computed from the F 2 functions of this model and are shown to agree with data well. It is also shown that the two-dimensional plot of the logarithm of a nonsinglet moment versus the logarithm of another such moment is not a good way to distinguish this nonpointlike-parton model from the QCD parton model

  11. Generalized polarizabilities of the nucleon in baryon chiral perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Lensky, Vadim [Johannes Gutenberg Universitaet Mainz, Institut fuer Kernphysik, Cluster of Excellence PRISMA, Mainz (Germany); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Pascalutsa, Vladimir; Vanderhaeghen, Marc [Johannes Gutenberg Universitaet Mainz, Institut fuer Kernphysik, Cluster of Excellence PRISMA, Mainz (Germany)

    2017-02-15

    The nucleon generalized polarizabilities (GPs), probed in virtual Compton scattering (VCS), describe the spatial distribution of the polarization density in a nucleon. They are accessed experimentally via the process of electron-proton bremsstrahlung (ep → epγ) at electron-beam facilities, such as MIT-Bates, CEBAF (Jefferson Lab), and MAMI (Mainz). We present the calculation of the nucleon GPs and VCS observables at next-to-leading order in baryon chiral perturbation theory (BχPT), and confront the results with the empirical information. At this order our results are predictions, in the sense that all the parameters are well known from elsewhere. Within the relatively large uncertainties of our calculation we find good agreement with the experimental observations of VCS and the empirical extractions of the GPs. We find large discrepancies with previous chiral calculations - all done in heavy-baryon χPT (HBχPT) - and discuss the differences between BχPT and HBχPT responsible for these discrepancies. (orig.)

  12. Pseudoscalar Meson Electroproduction and Transversity

    International Nuclear Information System (INIS)

    Goldstein, G.; Liuti, S.

    2011-01-01

    Exclusive meson leptoproduction from nucleons in the deeply virtual exchanged boson limit can be described by generalized parton distributions (GPDs). Including spin dependence in the description requires 8 independent quark-parton and gluon-parton functions. The chiral even subset of 4 quark-nucleon GPDs are related to nucleon form factors and to parton distribution functions. The chiral odd set of 4 quark-nucleon GPDs are related to transversity, the tensor charge, and other quantities related to transversity. Different meson or photon production processes access different combinations of GPDs. This is analyzed in terms of t-channel exchange quantum numbers, J PC and it is shown that pseudoscalar production can isolate chiral odd GPDs. There is a sensitive dependence in various cross sections and asymmetries on the tensor charge of the nucleon and other transversity parameters. In a second section, analyticity and completeness are shown to limit the partonic interpret ation of the GPDs in the ERBL region.

  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. Nucleon structure from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dinter, Simon

    2012-11-13

    In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a{sup 2}) discretization effects.

  15. Nucleon structure from lattice QCD

    International Nuclear Information System (INIS)

    Dinter, Simon

    2012-01-01

    In this thesis we compute within lattice QCD observables related to the structure of the nucleon. One part of this thesis is concerned with moments of parton distribution functions (PDFs). Those moments are essential elements for the understanding of nucleon structure and can be extracted from a global analysis of deep inelastic scattering experiments. On the theoretical side they can be computed non-perturbatively by means of lattice QCD. However, since the time lattice calculations of moments of PDFs are available, there is a tension between these lattice calculations and the results from a global analysis of experimental data. We examine whether systematic effects are responsible for this tension, and study particularly intensively the effects of excited states by a dedicated high precision computation. Moreover, we carry out a first computation with four dynamical flavors. Another aspect of this thesis is a feasibility study of a lattice QCD computation of the scalar quark content of the nucleon, which is an important element in the cross-section of a heavy particle with the nucleon mediated by a scalar particle (e.g. Higgs particle) and can therefore have an impact on Dark Matter searches. Existing lattice QCD calculations of this quantity usually have a large error and thus a low significance for phenomenological applications. We use a variance-reduction technique for quark-disconnected diagrams to obtain a precise result. Furthermore, we introduce a new stochastic method for the calculation of connected 3-point correlation functions, which are needed to compute nucleon structure observables, as an alternative to the usual sequential propagator method. In an explorative study we check whether this new method is competitive to the standard one. We use Wilson twisted mass fermions at maximal twist in all our calculations, such that all observables considered here have only O(a 2 ) discretization effects.

  16. Gluon distributions in nucleons and pions at a low resolution scale

    International Nuclear Information System (INIS)

    Christiansen, H.R.

    2000-10-01

    In this paper we study the gluon distribution functions in nucleons and pions at a low resolution Q 2 scale. This is an important issue since parton densities at low Q 2 have always been taken as an external input which is adjusted through DGLAP evolution to fit the experimental data at higher scales. Here, in the framework of a model recently developed, it is shown that the hypothetical cloud of neutral pions surrounding nucleons and pions appears to be responsible for the characteristic valence-like gluon distributions needed at the initial low scale. As an additional result, we get the remarkable prediction that neutral and charged ions have different intrinsic sea flavor contents. (author)

  17. Unmatter Entities inside Nuclei, Predicted by the Brightsen Nucleon Cluster Model

    Directory of Open Access Journals (Sweden)

    Smarandache F.

    2006-01-01

    Full Text Available Applying the R. A. Brightsen Nucleon Cluster Model of the atomic nucleus we discuss how unmatter entities (the conjugations of matter and antimatter may be formed as clusters inside a nucleus. The model supports a hypothesis that antimatter nucleon clusters are present as a parton (sensu Feynman superposition within the spatial confinement of the proton (1H1, the neutron, and the deuteron (1H2. If model predictions can be confirmed both mathematically and experimentally, a new physics is suggested. A proposed experiment is connected to othopositronium annihilation anomalies, which, being related to one of known unmatter entity, orthopositronium (built on electron and positron, opens a way to expand the Standard Model.

  18. The general behavior of NLO unintegrated parton distributions based on the single-scale evolution and the angular ordering constraint

    International Nuclear Information System (INIS)

    Hosseinkhani, H.; Modarres, M.

    2011-01-01

    To overcome the complexity of generalized two hard scale (k t ,μ) evolution equation, well known as the Ciafaloni, Catani, Fiorani and Marchesini (CCFM) evolution equations, and calculate the unintegrated parton distribution functions (UPDF), Kimber, Martin and Ryskin (KMR) proposed a procedure based on (i) the inclusion of single-scale (μ) only at the last step of evolution and (ii) the angular ordering constraint (AOC) on the DGLAP terms (the DGLAP collinear approximation), to bring the second scale, k t into the UPDF evolution equations. In this work we intend to use the MSTW2008 (Martin et al.) parton distribution functions (PDF) and try to calculate UPDF for various values of x (the longitudinal fraction of parton momentum), μ (the probe scale) and k t (the parton transverse momentum) to see the general behavior of three-dimensional UPDF at the NLO level up to the LHC working energy scales (μ 2 ). It is shown that there exits some pronounced peaks for the three-dimensional UPDF(f a (x,k t )) with respect to the two variables x and k t at various energies (μ). These peaks get larger and move to larger values of k t , as the energy (μ) is increased. We hope these peaks could be detected in the LHC experiments at CERN and other laboratories in the less exclusive processes.

  19. Generalized parton distributions and transversity from full lattice QCD

    Science.gov (United States)

    Göckeler, M.; Hägler, Ph.; Horsley, R.; Pleiter, D.; Rakow, P. E. L.; Schäfer, A.; Schierholz, G.; Zanotti, J. M.; Qcdsf Collaboration

    2005-06-01

    We present here the latest results from the QCDSF collaboration for moments of gener- alized parton distributions and transversity in two-flavour QCD, including a preliminary analysis of the pion mass dependence.

  20. Phenomenology of leading nucleon production in e p collisions at HERA in the framework of fracture functions

    Science.gov (United States)

    Shoeibi, Samira; Taghavi-Shahri, F.; Khanpour, Hamzeh; Javidan, Kurosh

    2018-04-01

    In recent years, several experiments at the e-p collider HERA have collected high precision deep-inelastic scattering (DIS) data on the spectrum of leading nucleon carrying a large fraction of the proton's energy. In this paper, we have analyzed recent experimental data on the production of forward protons and neutrons in DIS at HERA in the framework of a perturbative QCD. We propose a technique based on the fractures functions framework, and extract the nucleon fracture functions (FFs) M2(n /p )(x ,Q2;xL) from global QCD analysis of DIS data measured by the ZEUS Collaboration at HERA. We have shown that an approach based on the fracture functions formalism allows us to phenomenologically parametrize the nucleon FFs. Considering both leading neutron as well as leading proton production data at HERA, we present the results for the separate parton distributions for all parton species, including valence quark densities, the antiquark densities, the strange sea distribution, and the gluon distribution functions. We proposed several parametrizations for the nucleon FFs and open the possibility of these asymmetries. The obtained optimum set of nucleon FFs is accompanied by Hessian uncertainty sets which allow one to propagate uncertainties to other observables interest. The extracted results for the t -integrated leading neutron F2LN (3 )(x ,Q2;xL) and leading proton F2LP (3 )(x ,Q2;xL) structure functions are in good agreement with all data analyzed, for a wide range of fractional momentum variable x as well as the longitudinal momentum fraction xL.

  1. Global QCD Analysis of the Nucleon Tensor Charge with Lattice QCD Constraints

    Science.gov (United States)

    Shows, Harvey, III; Melnitchouk, Wally; Sato, Nobuo

    2017-09-01

    By studying the parton distribution functions (PDFs) of a nucleon, we probe the partonic scale of nature, exploring what it means to be a nucleon. In this study, we are interested in the transversity PDF-the least studied of the three collinear PDFs. By conducting a global analysis on experimental data from semi-inclusive deep inelastic scattering (SIDIS), as well as single-inclusive e+e- annihilation (SIA), we extract the fit parameters needed to describe the transverse moment dependent (TMD) transversity PDF, as well as the Collins fragmentation function. Once the collinear transversity PDF is obtained by integrating the extracted TMD PDF, we wish to resolve discrepancies between lattice QCD calculations and phenomenological extractions of the tensor charge from data. Here we show our results for the transversity distribution and tensor charge. Using our method of iterative Monte Carlo, we now have a more robust understanding of the transversity PDF. With these results we are able to progress in our understanding of TMD PDFs, as well as testify to the efficacy of current lattice QCD calculations. This work is made possible through support from NSF award 1659177 to Old Dominion University.

  2. The average number of partons per clan in rapidity intervals in parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Giovannini, A. [Turin Univ. (Italy). Ist. di Fisica Teorica; Lupia, S. [Max-Planck-Institut fuer Physik, Muenchen (Germany). Werner-Heisenberg-Institut; Ugoccioni, R. [Lund Univ. (Sweden). Dept. of Theoretical Physics

    1996-04-01

    The dependence of the average number of partons per clan on virtuality and rapidity variables is analytically predicted in the framework of the Generalized Simplified Parton Shower model, based on the idea that clans are genuine elementary subprocesses. The obtained results are found to be qualitatively consistent with experimental trends. This study extends previous results on the behavior of the average number of clans in virtuality and rapidity and shows how important physical quantities can be calculated analytically in a model based on essentials of QCD allowing local violations of the energy-momentum conservation law, still requiring its global validity. (orig.)

  3. The average number of partons per clan in rapidity intervals in parton showers

    International Nuclear Information System (INIS)

    Giovannini, A.; Lupia, S.; Ugoccioni, R.

    1996-01-01

    The dependence of the average number of partons per clan on virtuality and rapidity variables is analytically predicted in the framework of the Generalized Simplified Parton Shower model, based on the idea that clans are genuine elementary subprocesses. The obtained results are found to be qualitatively consistent with experimental trends. This study extends previous results on the behavior of the average number of clans in virtuality and rapidity and shows how important physical quantities can be calculated analytically in a model based on essentials of QCD allowing local violations of the energy-momentum conservation law, still requiring its global validity. (orig.)

  4. Calculations with off-shell matrix elements, TMD parton densities and TMD parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Bury, Marcin; Hameren, Andreas van; Kutak, Krzysztof; Sapeta, Sebastian [Polish Academy of Sciences, Institute of Nuclear Physics, Cracow (Poland); Jung, Hannes [Polish Academy of Sciences, Institute of Nuclear Physics, Cracow (Poland); DESY, Hamburg (Germany); Serino, Mirko [Polish Academy of Sciences, Institute of Nuclear Physics, Cracow (Poland); Ben Gurion University of the Negev, Department of Physics, Beersheba (Israel)

    2018-02-15

    A new calculation using off-shell matrix elements with TMD parton densities supplemented with a newly developed initial state TMD parton shower is described. The calculation is based on the KaTie package for an automated calculation of the partonic process in high-energy factorization, making use of TMD parton densities implemented in TMDlib. The partonic events are stored in an LHE file, similar to the conventional LHE files, but now containing the transverse momenta of the initial partons. The LHE files are read in by the Cascade package for the full TMD parton shower, final state shower and hadronization from Pythia where events in HEPMC format are produced. We have determined a full set of TMD parton densities and developed an initial state TMD parton shower, including all flavors following the TMD distribution. As an example of application we have calculated the azimuthal de-correlation of high p{sub t} dijets as measured at the LHC and found very good agreement with the measurement when including initial state TMD parton showers together with conventional final state parton showers and hadronization. (orig.)

  5. A quark-parton description of the deep inelastic scattering processes

    International Nuclear Information System (INIS)

    Bajpai, R.P.

    1977-01-01

    A consistent description of various deep inelastic processes in a quark-parton model is presented. The valence quark probability distribution and the form of core quark probability distribution is fixed from the deep inelastic electroproduction data. Langacker and Suzuki prescription is used to fix the p and n quark core distribution. The differential excitation of quark currents similar to the Harari model of e + e - annihilation process is invoked in deep inelastic electroproduction and neutrino reactions. An effective phenomenological form of the weak currents associated with new quarks and the associated nucleon structure is determined. (author)

  6. Covariant extension of the GPD overlap representation at low Fock states

    Energy Technology Data Exchange (ETDEWEB)

    Chouika, N.; Moutarde, H. [Univ. Paris-Saclay, Gif-sur-Yvette (France). IRFU, CEA; Mezrag, C. [Argonne National Laboratory, Argonne, IL (United States). Physics Div.; Istituto Nazionale di Fisica Nucleare, Rome (Italy); Rodriguez-Quintero, J. [Huelva Univ. (Spain). Dept. Ciencias Integradas

    2017-12-15

    We present a novel approach to compute generalized parton distributions within the lightfront wave function overlap framework. We show how to systematically extend generalized parton distributions computed within the DGLAP region to the ERBL one, fulfilling at the same time both the polynomiality and positivity conditions. We exemplify our method using pion lightfront wave functions inspired by recent results of non-perturbative continuum techniques and algebraic nucleon lightfront wave functions. We also test the robustness of our algorithm on reggeized phenomenological parameterizations. This approach paves the way to a better understanding of the nucleon structure from non-perturbative techniques and to a unification of generalized parton distributions and transverse momentum dependent parton distribution functions phenomenology through lightfront wave functions. (orig.)

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

    International Nuclear Information System (INIS)

    Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Koutsou, Giannis

    2015-03-01

    We perform a lattice computation of the flavour octet contribution to the average quark momentum in a nucleon, left angle x right angle (8) μ 2 =4 GeV 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 (3) )/(left angle x right angle (8) ) (with left angle x right angle (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 (3) )/(left angle x right angle (8) )=0.39(1)(4).

  8. Multi-hadron-state contamination in nucleon observables from chiral perturbation theory

    Science.gov (United States)

    Bär, Oliver

    2018-03-01

    Multi-particle states with additional pions are expected to be a non-negligible source of the excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory (ChPT) can be employed to calculate the contamination due to two-particle nucleon-pion states in various nucleon observables. Results to leading order are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions: the average quark momentum fraction, the helicity and the transversity moment. Taking into account experimental and phenomenological results for the charges and moments the impact of the nucleon-pionstates on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution leads to an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. Existing lattice data is not in conflict with the ChPT predictions, but the comparison suggests that significantly larger source-sink separations are needed to compute the charges and moments with few-percent precision. Talk given at the 35th International Symposium on Lattice Field Theory, 18 - 24 June 2017, Granada, Spain.

  9. Eikonal propagators and high-energy parton-parton scattering in gauge theories

    International Nuclear Information System (INIS)

    Meggiolaro, Enrico

    2001-01-01

    In this paper we consider 'soft' high-energy parton-parton scattering processes in gauge theories, i.e., elastic scattering processes involving partons at very high squared energies s in the center of mass and small squared transferred momentum t (s→∞, t 2 ). By a direct resummation of perturbation theory in the limit we are considering, we derive expressions for the truncated-connected quark (antiquark) propagator in an external gluon field, as well as for the residue at the pole of the full unrenormalized propagator, both for scalar and fermion gauge theories. These are the basic ingredients to derive high-energy parton-parton scattering amplitudes, using the LSZ reduction formulae and a functional integral approach. The above procedure is also extended to include the case in which at least one of the partons is a gluon. The meaning and the validity of the results are discussed

  10. Central limit theorem in quantum field theory, generalized partons and application to deep-inelastic scattering

    International Nuclear Information System (INIS)

    Manoukian, E.B.

    1986-01-01

    We prove the following elementary theorem. If diameter 1 ,...,diametersub(N) is a sequence of fields having identical, though arbitrary, interactions but not interacting with each other and =0, i=1,...,N, then the generating functional of the ''average'' field diametersup((N))=(diameter 1 +...+diametersub((N))/√N, for N->infinite, may be explicitly obtained and may be written in terms of the two-point function of any of the fields diametersub(i). The theorem is then applied to define generalized parton fields PSIsub(j)=Σsup(N)sub(i)=1 PSIij/√N as ''averages'' of basic fields PSIsub(ij) having arbitrary interactions but not interacting with each other. We show that in the limit N->infinite Bjorken scaling, as observed at energies not too high, may be obtained if only quanta associated with generalized parton fields are excited in the hadron by the virtual photon with no reference to the details of the underlying dynamics. For N< infinite, and the excitation of other quanta as well lead to a systematic breaking of scale invariance and the details of the dynamics are necessarily recovered which are expected to be applicable at higher energy regimes. (orig.)

  11. Spin of two-nucleon system and nucleon-antinucleon combination in the S-state

    International Nuclear Information System (INIS)

    Baranik, A.T.; El-Naghy, A.; Ramadan, S.

    1988-08-01

    The spin of the two nucleon combination was studied. It was found that the resultant combination could be treated as a boson with spin one or zero, and the spin one state is more stable than the spin zero state. In the case of nucleon-antinucleon combination the spin zero state is more stable than the spin one state. The approach succeeded in describing the general features of the nucleon-nucleon and nucleon antinucleon scattering and polarization. (author). 3 refs, 4 figs

  12. Transverse charge and magnetization densities in the nucleon's chiral periphery

    Energy Technology Data Exchange (ETDEWEB)

    Granados, Carlos G. [JLAB Newport News, VA (United States); Weiss, Christian [JLAB Newport News, VA (United States)

    2014-01-01

    In the light-front description of nucleon structure the electromagnetic form factors are expressed in terms of frame-independent transverse densities of charge and magnetization. Recent work has studied the transverse densities at peripheral distances b = O(M{pi}{sup -1}), where they are governed by universal chiral dynamics and can be computed in a model-independent manner. Of particular interest is the comparison of the peripheral charge and magnetization densities. We summarize (a) their interpretation as spin-independent and -dependent current matrix elements; (b) the leading-order chiral effective field theory results; (c) their mechanical interpretation in the light-front formulation; (d) the large-N_c limit of QCD and the role of {Delta} intermediate states; (e) the connection with generalized parton distributions and peripheral high-energy scattering processes.

  13. Polarized Parton Distributions at an Electron-Ion Collider

    CERN Document Server

    Ball, Richard D.; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

    2014-01-01

    We study the potential impact of inclusive deep-inelastic scattering data from a future electron-ion collider (EIC) on longitudinally polarized parton distribution (PDFs). We perform a PDF determination using the NNPDF methodology, based on sets of deep-inelastic EIC pseudodata, for different realistic choices of the electron and proton beam energies. We compare the results to our current polarized PDF set, NNPDFpol1.0, based on a fit to fixed-target inclusive DIS data. We show that the uncertainties on the first moments of the polarized quark singlet and gluon distributions are substantially reduced in comparison to NNPDFpol1.0, but also that more measurements may be needed to ultimately pin down the size of the gluon contribution to the nucleon spin.

  14. Polarized parton distributions at an electron–ion collider

    Energy Technology Data Exchange (ETDEWEB)

    Ball, Richard D. [Tait Institute, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh EH9 3JZ, Scotland (United Kingdom); Forte, Stefano [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Guffanti, Alberto [The Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Nocera, Emanuele R. [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Genova (Italy); Rojo, Juan [PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland)

    2014-01-20

    We study the potential impact of inclusive deep-inelastic scattering data from a future electron–ion collider (EIC) on longitudinally polarized parton distributions (PDFs). We perform a PDF determination using the NNPDF methodology, based on sets of deep-inelastic EIC pseudodata, for different realistic choices of the electron and proton beam energies. We compare the results to our current polarized PDF set, NNPDFpol1.0, based on a fit to fixed-target inclusive DIS data. We show that the uncertainties on the first moments of the polarized quark singlet and gluon distributions are substantially reduced in comparison to NNPDFpol1.0, but also that more measurements may be needed to ultimately pin down the size of the gluon contribution to the nucleon spin.

  15. Polarized parton distributions at an electron–ion collider

    International Nuclear Information System (INIS)

    Ball, Richard D.; Forte, Stefano; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

    2014-01-01

    We study the potential impact of inclusive deep-inelastic scattering data from a future electron–ion collider (EIC) on longitudinally polarized parton distributions (PDFs). We perform a PDF determination using the NNPDF methodology, based on sets of deep-inelastic EIC pseudodata, for different realistic choices of the electron and proton beam energies. We compare the results to our current polarized PDF set, NNPDFpol1.0, based on a fit to fixed-target inclusive DIS data. We show that the uncertainties on the first moments of the polarized quark singlet and gluon distributions are substantially reduced in comparison to NNPDFpol1.0, but also that more measurements may be needed to ultimately pin down the size of the gluon contribution to the nucleon spin

  16. Measurement of Hadron Multiplicities in Deep Inelastic Muon-Nucleon Scattering

    CERN Document Server

    du Fresne von Hohenesche, Nicolas

    2016-06-02

    In deep-inelastic muon-nucleon scattering, a single quark can be ejected out of the nucleon by the absorption of a high-energy photon. Such a free isolated quark has never been observed in nature. In quantum chromodynamics (QCD), coloured objects, such as a single quark, create additional quark anti-quark pairs out of the colour field and the final state comprises a jet of hadrons. The hadronisation process can be described by fragmentation functions D_q^h, the probability that a quark with the flavour q turns into a hadron of the type h. Similar to the parton distribution function, the fragmentation functions are fundamental, universal and process-independent quantities. The fragmentation functions are measured with the COM- PASS spectrometer in muon-nucleon scattering. The observables are the hadron multiplicities M_h. The COMPASS experiment consists of a two-stage magnetic spectrometer located at the M2 beam line of the Super Proton Synchrotron at CERN and uses a polarised muon beam on a nuclear fixed targ...

  17. The Q2-Dependence of the Gross-Llewellyn Smith Sum Rule and of the Parton Distributions

    International Nuclear Information System (INIS)

    Kataev, A.L.; AN SSSR, Moscow; Sidorov, A.V.

    1994-01-01

    We describe the results of our recent work on the determination of the value of the parameter Λ and of the Q 2 -dependence of the Gross-Llewellyn Smith (GLS) sum rule from the experimental data of the CCFR collaboration on neutrino-nucleon deep inelastic scattering, using the Jacobi polynomials QCD analysis. The new information on the Q 2 -dependence of the parton distributions is presented. 37 refs., 3 figs., 3 tabs

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

    International Nuclear Information System (INIS)

    Alexandrou, Constantia; Cyprus Institute, Nicosia; Deutsches Elektronen-Synchrotron; Cichy, Krzysztof; Poznan Univ.; Drach, Vincent; Garcia-Ramos, Elena; Humboldt-Universitaet, Berlin; Hadjiyiannakou, Kyriakos; Jansen, Karl; Steffens, Fernanda; Wiese, Christian

    2014-11-01

    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.

  19. 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.

  20. Extraction of Generalized Parton Distributions from combined Deeply Virtual Compton Scattering and Timelike Compton scattering fits

    Science.gov (United States)

    Boer, Marie

    2017-09-01

    Generalized Parton Distributions (GPDs) contain the correlation between the parton's longitudinal momentum and their transverse distribution. They are accessed through hard exclusive processes, such as Deeply Virtual Compton Scattering (DVCS). DVCS has already been measured in several experiments and several models allow for extracting GPDs from these measurements. Timelike Compton Scattering (TCS) is, at leading order, the time-reversal equivalent process to DVCS and accesses GPDs at the same kinematics. Comparing GPDs extracted from DVCS and TCS is a unique way for proving GPD universality. Combining fits from the two processes will also allow for better constraining the GPDs. We will present our method for extracting GPDs from DVCS and TCS pseudo-data. We will compare fit results from the two processes in similar conditions and present what can be expected in term of contraints on GPDs from combined fits.

  1. Experimental study of the nucleon spin structure

    Energy Technology Data Exchange (ETDEWEB)

    Litmaath, M.F.

    1996-05-07

    After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.).

  2. Experimental study of the nucleon spin structure

    International Nuclear Information System (INIS)

    Litmaath, M.F.

    1996-01-01

    After introducing the theoretical framework, which includes DIS, the Quark Parton Model (QPM) and QCD, we describe the implementation of the experiment. The SMC uses a beam of 190 GeV naturally polarized muons, scattering off nucleons in a large cryogenic target containing protons or deuterons that are polarized through Dynamic Nuclear Polarization (DNP). The target material is located in two cells in a row, with opposite polarizations. Every 5 hours the polarizations of both cells are reversed. The target polarization is measured by an NMR system. The polarization of the beam is measured in a polarimeter, located downstream of the main experimental setup. (orig.)

  3. 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

    Science.gov (United States)

    Geiger, Klaus

    1997-08-01

    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 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 treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. This article gives a brief review of the physics underlying VNI, which is followed by a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including a simple example), annotates input and control parameters, and discusses output data provided by it.

  4. Nucleon shadowing effects in Cu + Cu and Au + Au collisions at RHIC within the HIJING code

    Science.gov (United States)

    Abdel-Waged, Khaled; Felemban, Nuha

    2018-02-01

    The centrality dependence of pseudorapidity density of charged particles ({{{d}}{N}}{{ch}}/{{d}}η ) in Cu + Cu (Au + Au) collisions at Relativistic Heavy Ion Collider energy of \\sqrt{{s}{{NN}}}=22.4, 62.4 and 200 (19.6, 62.4 and 200) GeV, is investigated within an improved HIJING code. The standard HIJING model is enhanced by a prescription for collective nucleon-nucleon (NN) interactions and more modern parton distribution functions. The collective NN-interactions are used to induce both cascade and nucleon shadowing effects. We find collective cascade broadens the pseudorapidity distributions in the tails (at | η | > {y}{beam}) above 25%-30% collision centrality to be consistent with the {{{d}}{N}}{{ch}}/{{d}}η data at \\sqrt{{s}{{NN}}} =19.6,22.4,62.4 {GeV}. The overall contribution of nucleon shadowing is shown to depress the whole shape of {{{d}}{N}}{{ch}}/{{d}}η in the primary interaction region (at | η | data.

  5. Structure functions and parton distributions

    International Nuclear Information System (INIS)

    Olness, F.; Tung, Wu-Ki

    1991-04-01

    Activities of the structure functions and parton distributions group is summarized. The impact of scheme-dependence of parton distributions (especially sea-quarks and gluons) on the quantitative formulation of the QCD parton model is highlighted. Recent progress on the global analysis of parton distributions is summarized. Issues on the proper use of the next-to-leading parton distributions are stressed

  6. Nucleon Viewed as a Borromean Bound-State

    Science.gov (United States)

    Segovia, Jorge; Mezrag, Cédric; Chang, Lei; Roberts, Craig D.

    2018-05-01

    We explain how the emergent phenomenon of dynamical chiral symmetry breaking ensures that Poincaré covariant analyses of the three valence-quark scattering problem in continuum quantum field theory yield a picture of the nucleon as a Borromean bound-state, in which binding arises primarily through the sum of two separate contributions. One involves aspects of the non-Abelian character of Quantum Chromodynamics that are expressed in the strong running coupling and generate tight, dynamical color-antitriplet quark-quark correlations in the scalar-isoscalar and pseudovector-isotriplet channels. This attraction is magnified by quark exchange associated with diquark breakup and reformation, which is required in order to ensure that each valence-quark participates in all diquark correlations to the complete extent allowed by its quantum numbers. Combining these effects, we arrive at a properly antisymmetrised Faddeev wave function for the nucleon and calculate, e.g. the flavor-separated versions of the Dirac and Pauli form factors and the proton's leading-twist parton distribution amplitude. We conclude that available data and planned experiments are capable of validating the proposed picture.

  7. Transverse target-spin asymmetry associated with deeply virtual Compton scattering on the proton and a resulting model-dependent constraint on the total angular momentum of quarks in the nucleon

    International Nuclear Information System (INIS)

    Ye, Zhenyu

    2007-02-01

    In this thesis we report on the rst results on the transverse target-spin asymmetry associated with deeply virtual Compton scattering on the proton. It is shown that this asymmetry can provide one of the rare possibilities to access the Generalized Parton Distribution (GPD) E of the nucleon, and thus, through models for E, also to the total angular momentum of u and d quarks in the nucleon. The measurement was performed using the 27.6 GeV positron beam of the HERA storage ring and the transversely polarized hydrogen target of the HERMES experiment at DESY. The two leading azimuthal amplitudes of the asymmetry are extracted from the HERMES 2002-2004 data, corresponding to an integrated luminosity of 65.3 pb.1. By comparing the results obtained at HERMES and theoretical predictions based on a phenomenological model of GPDs, we obtain a model-dependent constraint on the total angular momentum of quarks in the nucleon. (orig.)

  8. Transverse target-spin asymmetry associated with deeply virtual Compton scattering on the proton and a resulting model-dependent constraint on the total angular momentum of quarks in the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Zhenyu

    2007-02-15

    In this thesis we report on the rst results on the transverse target-spin asymmetry associated with deeply virtual Compton scattering on the proton. It is shown that this asymmetry can provide one of the rare possibilities to access the Generalized Parton Distribution (GPD) E of the nucleon, and thus, through models for E, also to the total angular momentum of u and d quarks in the nucleon. The measurement was performed using the 27.6 GeV positron beam of the HERA storage ring and the transversely polarized hydrogen target of the HERMES experiment at DESY. The two leading azimuthal amplitudes of the asymmetry are extracted from the HERMES 2002-2004 data, corresponding to an integrated luminosity of 65.3 pb.1. By comparing the results obtained at HERMES and theoretical predictions based on a phenomenological model of GPDs, we obtain a model-dependent constraint on the total angular momentum of quarks in the nucleon. (orig.)

  9. Measurement of continuum dimuon production in 800-GeV/C proton nucleon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Jason C. [New Mexico State Univ., Las Cruces, NM (United States)

    2003-01-01

    Fermilab Experiment 866 has performed an absolute measurement of continuum dimuon (Drell-Yan) cross sections in 800-GeV/c pp and pd interactions. Results differential in the mass, Feynman-x (xF ) and transverse momenta (pT ) of the dimuon pairs are reported. These results represent the most extensive study of the Drell-Yan process to date, based on a data sample of 175,000 dimuon events covering the widest range in kinematics yet achieved (4.2≤ M ≤ 16.85 GeV and -0.05 ≤ xF ≤ 0.8) with this level of precision. The cross sections are primarily sensitive to the magnitude and shape of the light antiquark distributions ( $\\bar{d}$(x) and $\\bar{u}$(x)) in the nucleon, but also provide important information on the valence quarks as well as the gluons. They are in good agreement with other existing proton-induced Drell-Yan experiments. There is also general agreement between the data and next-to-leading-order calculations based on various sets of parton distribution functions. Differences between data and theory are examined, and the potential impact of these data on future parameterizations of the parton distributions are be discussed.

  10. Exclusive Electroproduction of meson rho on the nucleon Virtualite Intermediate With the CLAS Detector at Jlab; Electroproduction Exclusive de meson rho sur le nucleon Virtualite Intermediaire Avec le Detecteur CLAS at Jlab

    Energy Technology Data Exchange (ETDEWEB)

    Hadjidakis, Cynthia [Univ. of Paris-Sud, Orsay (France). Inst. of Nuclear Physics of Orsay

    2002-12-17

    This report presents the exclusive rho0 meson electroproduction on the nucleon at intermediate square momentum transfers Q2 (1.5 < Q2 < 3 GeV2) and above the resonance region. The experiment has been taken place at the Jefferson laboratory with the CLAS detector, with a 4.2 GeV beam energy on a hydrogen target in the February-March 1999 period. They present the results and in particular the L/T separated cross sections. This experimentally unexplored domain experimentally is at the intersection between traditional ''soft'' hadronic physics models (VDM and Regge inspired models) and ''hard'' pQCD inspired approaches (recently introduced Generalized Parton Distribution). They discuss both approaches and their domain of validity.

  11. 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.

  12. Parton distributions with LHC data

    CERN Document Server

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

    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 determinations, all the relevant LHC data for which experimental systematic uncertainties are currently available: ATLAS and LHCb W and Z lepton 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 with each other and with all the older data sets included in the fit. We present predictions for various ...

  13. Double parton interactions in photon+3 jet events in ppbar collisions sqrt{s}=1.96 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Abazov, V.M.; /Dubna, JINR; Abbott, B.; /Oklahoma U.; Abolins, M.; /Michigan State U.; Acharya, B.S.; /Tata Inst.; Adams, M.; /Illinois U., Chicago; Adams, T.; /Florida State U.; Aguilo, E.; /Simon Fraser U. /York U., Canada; Alexeev, G.D.; /Dubna, JINR; Alkhazov, G.; /St. Petersburg, INP; Alton, A.; /Michigan State U.; Alverson, G.; /Northeastern U. /Rio de Janeiro, CBPF

    2009-12-01

    We have used a sample of photon+3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb{sup -1} to determine the fraction of events with double parton scattering (f{sub DP}) in a single ppbar collision at {radical}s = 1.96 TeV. The DP fraction and effective cross section (sigma{sub eff}), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in p{sub T}) jet transverse momentum pT{sub jet2} within the range 15 < pT{sub jet2} < 30 GeV. In this range, f{sub DP} varies between 0.23 < f{sub DP} < 0.47, while sigma{sub eff} has the average value sigma{sub effave} = 16.4 {+-} 0.3(stat) {+-} 2.3(syst) mb.

  14. The dependence of J/ψ-nucleon inelastic cross section on the Feynman variable

    International Nuclear Information System (INIS)

    Duan Chungui; Liu Na; Miao Wendan

    2011-01-01

    By means of two typical sets of nuclear parton distribution functions, meanwhile taking account of the energy loss of the beam proton and the nuclear absorption of the charmonium states traversing the nuclear matter in the uniform framework of the Glauber model, a leading order phenomenological analysis is given in the color evaporation model of the E866 experimental data on J/ψ production differential cross section ratios R Fe/Be (x F ). It is shown that the energy loss effect of beam proton on R Fe/Be (x F ) is more important than the nuclear effects on parton distribution functions in the high Feynman variable x F region. It is found that the J/ψ-nucleon inelastic cross section depends on the Feynman variable x F and increases linearly with x F in the region x F > 0.2. (authors)

  15. Nucleon-nucleon theory and phenomenology

    International Nuclear Information System (INIS)

    Signell, P.

    1981-03-01

    This project involves five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 0-1200 MeV range that can be used by all nucleon-nucleon reseachers

  16. Nucleon internal structure: a new set of quark, gluon momentum, angular momentum operators and parton distribution functions

    International Nuclear Information System (INIS)

    Wang Fan; Sun Weimin; Chen Xiangsong; Lu Xiaofu; Goldman, T.

    2009-01-01

    It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relation. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relation, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed. (authors)

  17. Lattice QCD Calculation of Nucleon Structure

    International Nuclear Information System (INIS)

    Liu, Keh-Fei; Draper, Terrence

    2016-01-01

    It is emphasized in the 2015 NSAC Long Range Plan that 'understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics.' Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out first-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large-scale computer simulation. We started out by calculating the nucleon form factors -- electromagnetic, axial-vector, ?NN, and scalar form factors, the quark spin contribution to the proton spin, the strangeness magnetic moment, the quark orbital angular momentum, the quark momentum fraction, and the quark and glue decomposition of the proton momentum and angular momentum. The first round of calculations were done with Wilson fermions in the 'quenched' approximation where the dynamical effects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge configurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at ~ 300 MeV and obtained the strange form factors, charm and strange quark masses, the charmonium spectrum and the D_s meson decay constant f_D__s, the strangeness and charmness, the meson mass decomposition and the strange quark spin from the

  18. Complex conjugate poles and parton distributions

    International Nuclear Information System (INIS)

    Tiburzi, B.C.; Detmold, W.; Miller, G.A.

    2003-01-01

    We calculate parton and generalized parton distributions in Minkowski space using a scalar propagator with a pair of complex conjugate poles. Correct spectral and support properties are obtained only after careful analytic continuation from Euclidean space. Alternately the quark distribution function can be calculated from modified cutting rules, which put the intermediate state on its complex mass shells. Distribution functions agree with those resulting from the model's Euclidean space double distribution which we calculate via nondiagonal matrix elements of twist-two operators. Thus one can use a wide class of analytic parametrizations of the quark propagator to connect Euclidean space Green functions to light-cone dominated amplitudes

  19. Parton saturation and $N_{part}$ scaling of semi-hard processes in QCD

    CERN Document Server

    Kharzeev, Dima E; McLerran, L; 10.1016/S0370-2693(03)00420-9

    2003-01-01

    We argue that the suppression of high p/sub t/ hadrons discovered recently in heavy ion collisions at RHIC may be a consequence of saturation in the color glass condensate. We qualitatively and semi- quantitatively describe the data, in particular, the dependence upon the number of nucleon participants. We show that if parton saturation sets in at sufficiently small energy, then in nucleus-nucleus collisions at RHIC and LHC energies the cross sections of semi-hard processes should scale approximately with the number of participants, N/sub part/. Our results provide a possible explanation of both the absence of apparent jet quenching at SPS energies and its presence at RHIC. Under the same assumption we predict that in semi-central and central pA (dA) collisions at collider energies the dependence of semi-hard processes on the number of participating nucleons of the nucleus will change to ~(N/sub part//sup A/)/sup 1/2/. The forthcoming data on dA collisions will provide a crucial test of this description. (61 ...

  20. 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.

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

    OpenAIRE

    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 repre...

  2. Ordering variable for parton showers

    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

    2014-01-15

    The parton splittings in a parton shower are ordered according to an ordering variable, for example the transverse momentum of the daughter partons relative to the direction of the mother, the virtuality of the splitting, or the angle between the daughter partons. We analyze the choice of the ordering variable and conclude that one particular choice has the advantage of factoring softer splittings from harder splittings graph by graph in a physical gauge.

  3. Ordering variable for parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Zoltán [DESY,Notkestrasse 85, 22607 Hamburg (Germany); Soper, Davison E. [Institute of Theoretical Science, University of Oregon,Eugene, OR 97403-5203 (United States)

    2014-06-30

    The parton splittings in a parton shower are ordered according to an ordering variable, for example the transverse momentum of the daughter partons relative to the direction of the mother, the virtuality of the splitting, or the angle between the daughter partons. We analyze the choice of the ordering variable and conclude that one particular choice has the advantage of factoring softer splittings from harder splittings graph by graph in a physical gauge.

  4. Ordering variable for parton showers

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2014-01-01

    The parton splittings in a parton shower are ordered according to an ordering variable, for example the transverse momentum of the daughter partons relative to the direction of the mother, the virtuality of the splitting, or the angle between the daughter partons. We analyze the choice of the ordering variable and conclude that one particular choice has the advantage of factoring softer splittings from harder splittings graph by graph in a physical gauge.

  5. Parton-parton scattering at two-loops

    International Nuclear Information System (INIS)

    Tejeda Yeomans, M.E.

    2001-01-01

    Abstract We present an algorithm for the calculation of scalar and tensor one- and two-loop integrals that contribute to the virtual corrections of 2 → 2 partonic scattering. First, the tensor integrals are related to scalar integrals that contain an irreducible propagator-like structure in the numerator. Then, we use Integration by Parts and Lorentz Invariance recurrence relations to build a general system of equations that enables the reduction of any scalar integral (with and without structure in the numerator) to a basis set of master integrals. Their expansions in ε = 2 - D/2 have already been calculated and we present a summary of the techniques that have been used to this end, as well as a compilation of the expansions we need in the different physical regions. We then apply this algorithm to the direct evaluation of the Feynman diagrams contributing to the O(α s 4 ) one- and two-loop matrix-elements for massless like and unlike quark-quark, quark-gluon and gluon-gluon scattering. The analytic expressions we provide are regularised in Convensional Dimensional Regularisation and renormalised in the MS-bar scheme. Finally, we show that the structure of the infrared divergences agrees with that predicted by the application of Catani's formalism to the analysis of each partonic scattering process. The results presented in this thesis provide the complete calculation of the one- and two-loop matrix-elements for 2 → 2 processes needed for the next-to-next-to-leading order contribution to inclusive jet production at hadron colliders. (author)

  6. What is a parton shower?

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2017-05-01

    We consider idealized parton shower event generators that treat parton spin and color exactly, leaving aside the choice of practical approximations for spin and color. We investigate how the structure of such a parton shower generator is related to the structure of QCD. We argue that a parton shower with splitting functions proportional to αs can be viewed not just as a model, but as the lowest order approximation to a shower that is defined at any perturbative order. To support this argument, we present a formulation for a parton shower at order α k s for any k. Since some of the input functions needed are specified by their properties but not calculated, this formulation does not provide a useful recipe for an order α k s parton shower algorithm. However, in this formulation we see how the operators that generate the shower are related to operators that specify the infrared singularities of QCD.

  7. What is 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

    2017-05-15

    We consider idealized parton shower event generators that treat parton spin and color exactly, leaving aside the choice of practical approximations for spin and color. We investigate how the structure of such a parton shower generator is related to the structure of QCD. We argue that a parton shower with splitting functions proportional to αs can be viewed not just as a model, but as the lowest order approximation to a shower that is defined at any perturbative order. To support this argument, we present a formulation for a parton shower at order α{sup k}{sub s} for any k. Since some of the input functions needed are specified by their properties but not calculated, this formulation does not provide a useful recipe for an order α{sup k}{sub s} parton shower algorithm. However, in this formulation we see how the operators that generate the shower are related to operators that specify the infrared singularities of QCD.

  8. Collinear and transverse momentum dependent parton densities obtained with a parton branching method

    International Nuclear Information System (INIS)

    Lelek, Aleksandra

    2017-10-01

    We present a solution of the DGLAP evolution equations, written in terms of Sudakov form factors to describe the branching and no-branching probabilities, using a parton branching Monte Carlo method. We demonstrate numerically that this method reproduces the semi-analytical solutions. We show how this method can be used to determine Transverse Momentum Dependent (TMD) parton distribution functions, in addition to the usual integrated parton distributions functions. We discuss numerical effects of the boundary of soft gluon resolution scale parameter on the resulting parton distribution functions. We show that a very good fit of the integrated TMDs to high precision HERA data can be obtained over a large range in x and Q 2 .

  9. Collinear and transverse momentum dependent parton densities obtained with a parton branching method

    Energy Technology Data Exchange (ETDEWEB)

    Lelek, Aleksandra

    2017-10-15

    We present a solution of the DGLAP evolution equations, written in terms of Sudakov form factors to describe the branching and no-branching probabilities, using a parton branching Monte Carlo method. We demonstrate numerically that this method reproduces the semi-analytical solutions. We show how this method can be used to determine Transverse Momentum Dependent (TMD) parton distribution functions, in addition to the usual integrated parton distributions functions. We discuss numerical effects of the boundary of soft gluon resolution scale parameter on the resulting parton distribution functions. We show that a very good fit of the integrated TMDs to high precision HERA data can be obtained over a large range in x and Q{sup 2}.

  10. Parton distribution in relativistic hadrons

    International Nuclear Information System (INIS)

    Kopeliovich, B.Z.; Lapidus, L.I.; Zamolodchikov, Al.B.

    1979-01-01

    The distribution in the slow-parton number in the relativistic hadron is considered as a function of its rapidity (y). Neglecting corrections due to the tarton chain recombination the equation is derived and its explicit solution is found. It describes this distribution depending on the initial distribution at y approximately 1. Comparison with the reggeon diagrams results in relations between the parton model and the regaeon field theory parameters. The interpretation of the cutting rules in the framework of the parton model is presented. The numerical estimation of the parton model parameters is performed. It is shown that the slow-parton density corresponding to accessible energies seems to be close to the saturated density. Therefore, the enhanced graphs contributions turn out to be of considerable importance

  11. Polarized quark distributions in bound nucleon and polarized EMC effect in Thermodynamical Bag Model

    Energy Technology Data Exchange (ETDEWEB)

    Ganesamurthy, Kuppusamy, E-mail: udckgm@sify.co [Research Department of Physics, Urumu Dhanalakshmi College, Trichy 620019 (India); Sambasivam, Raghavan, E-mail: udcsam@sify.co [Research Department of Physics, Urumu Dhanalakshmi College, Trichy 620019 (India)

    2011-04-15

    The polarized parton distribution functions (PDFs) and nuclear structure functions are evaluated by the phenomenological Thermodynamical Bag Model for nuclear media {sup 7}Li and {sup 27}Al. The Fermi statistical distribution function which includes the spin degree of freedom is used in this statistical model. We predict a sizeable polarized EMC effect. The results of quark spin sum and axial coupling constant of bound nucleons are compared with theoretical predictions of modified Nambu-Jona-Lasinio (NJL) model by Bentz et al.

  12. Study of the baryon-baryon interaction in nucleon-nucleon and pion-deuteron scattering

    International Nuclear Information System (INIS)

    Fuchs, M.

    1993-01-01

    After the definition of the Hamiltonian in general form by meson production and absorption the transition to operators pursued, which connect only spaces with definite meson numbers. In this approximation first the self-energy of a single baryon was calculated in its full energy and momentum dependence. Then the formal expressions for the T matrices of nucleon-nucleon and pion-deuteron scattering were derived. The essential components of these expressions are the baryon-baryon T matrix ant transition amplitudes from pion-deuteron channels to baryon-baryon states. The central chapter dealt with the calculation of the baryon-baryon interaction for the general form of the vertices, with the solution of the binding problem and the baryon-baryon T matrix. Finally followed the results on the nucleon-nucleon and pion-deuteron scattering. For this first the transition amplitudes from pion-deuteron states to intermediate baryon-baryon states and the Born graphs of the pion-deuteron scattering had to be calculated. After some remarks to the transition from partial-wave decomposed T matrices to scattering observables an extensive representation of the total, partial, and differential cross sections and a series of spin observables (analyzing powers and spin correlations) for the elastic proton-proton, neutron-proton, and pion-deuteron scattering as well for the fusion reaction pp→πd and the breakup reaction πd→pp follows. Thereby the energies reached from the nucleon-nucleon respectively pion-deuteron threshold up to 100 MeV above the delta resonance

  13. Effects of subleading color in a parton shower

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2014-12-01

    Parton shower Monte Carlo event generators in which the shower evolves from hard splittings to soft splittings generally use the leading color (LC) approximation, which is the leading term in an expansion in powers of 1/N c 2 , where N c =3 is the number of colors. In the parton shower event generator DEDUCTOR, we have introduced a more general approximation, the LC+ approximation, that includes some of the color suppressed contributions. In this paper, we explore the differences in results between the LC approximation and the LC+ approximation. Numerical comparisons suggest that, for simple observables, the LC approximation is quite accurate. We also find evidence that for gap-between-jets cross sections neither the LC approximation nor the LC+ approximation is adequate.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-15

    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.

  15. Nucleon-nucleon scattering data

    International Nuclear Information System (INIS)

    Bystricky, J.; Lehar, F.

    1981-01-01

    The present review contains a compilation of p-p, n-n, n-p and p-n elastic scattering data, total cross sections for elastic and inelastic nucleon-nucleon processes as well as the slope parameters and the ratios of the real to the imaginary part of the forward scattering amplitude measured at all energies. The data are given in detailed tables with comments on each measurement. Summary tables, nucleon-nucleon kinematics formulae, transformation tables for kinematics, a detailed list of references and an author index complete the paper. (orig.)

  16. Radial excitations in nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Silvestre-Brac, B.; Carbonell, J.; Gignoux, C.

    1986-01-01

    In the non-relativistic constituent quark model, the role of the radial excitations of the nucleon is studied within a resonating group approach of the nucleon-nucleon scattering. It is shown that, rather than the inclusion of new channels, it is important to include mixed-symmetry spin-isospin components in the nucleon wave function. It is also found that during the collision there is no significant deformation of the nucleon. (orig.)

  17. Technical data on nucleonic gauges

    International Nuclear Information System (INIS)

    2005-07-01

    This nucleonic gauge manual and directory provides a reference database of nucleonic control systems available to potential users in the fields of exploration, exploitation and processing of natural resources and in the manufacturing industries. It starts with background information an the general principals of nucleonic gauges, followed by portable nuclear analysis systems (PNAS), computer tomography, cost-benefit on NCS (Nucleonic Control Systems) applications and trends and transfer of NCS technology. It continues with radiation protection and safety, discusses nucleonic gauges with low radioactivity sources and ends with typical models of nucleonic gauges. The basic principles of the most popular techniques are reviewed and reference data links to suppliers are provided. Information sheets on many typical commercial devices are also included. It will help end-users to select the most suitable alternative to solve a particular problem or to measure a certain parameter in a specific process

  18. Internal Spin Structure of the Nucleon in Polarized Deep Inelastic Muon-Nucleon Scattering

    International Nuclear Information System (INIS)

    Wislicki, W.

    1998-01-01

    We present the study of the internal spin structure of the nucleon in spin-dependent deep inelastic scattering of muons on nucleons. The data were taken by the NA47 experiment of the Spin Muon Collaboration (SMC) on the high energy muon beam at CERN. The experiment used the polarized proton and deuteron targets. The structure function g 1 p (x) and g 1 d (x) were determined from the asymmetries of the spin-dependent event rates in the range of 0.003 2 >=10 GeV 2 . Using the first moments of these structure functions an agreement with the Bjorken sum rule prediction was found within one standard deviation. The first moments of g 1 (x), for both proton and deuteron, are smaller than the Ellis-Jaffe sum rule prediction. This disagreement can be interpreted in terms of negative polarization of the strange sea in the nucleon. The singlet part of the axial current matrix element can be interpreted as an overall spin carried by quarks in the nucleon. Its value is significantly smaller than nucleon spin. Semi-inclusive asymmetries of yields of positive and negative hadrons produced on both targets were also measured and analysed in term of quark-parton model, together with inclusive asymmetries. From this analysis the quark spin distributions were determined, separately for valence u and d quarks and for non-strange sea quarks. Valence u quarks are positively polarized and their polarization increases with x. Valence d quarks are negatively polarized and their polarization does not exhibit any x-dependence. The non-strange sea is unpolarized in the whole measured range of x. The first moments of the valance quark spin distributions were found consistent with the values obtained from weak decay constants F and D and their second moments are consistent with lattice QCD calculations. In the QCD analysis of the world data the first moment of the gluon spin distribution was found with a large error. Also, a search for a non-perturbative anomaly at high x was done on the world

  19. Nucleon-nucleon scattering and different meson exchanges

    International Nuclear Information System (INIS)

    Osman, A.

    1985-10-01

    The iterative and noniterative diagrams with different meson exchange are investigated. The α, πβ and πγ meson exchange, (where α=π, rho, σ, ω, eta and delta; β=π, rho, σ and ω; γ=π and rho), are considered. These diagrams are taken to involve the nucleon-nucleon, the nucleon-isobar and the isobar-isobar intermediate states. The diagrams are calculated in momentum space following the noncovariant perturbation theory. The role of each of these diagrams is examined by calculating its contribution to the nucleon-nucleon interaction. The potential model is taken to include one-boson-exchange terms in addition to these diagrams. The nucleon-nucleon scattering phase shifts are described successfully showing the importance of tensor force. The contributions of the different parts are studied in the nucleon-nucleon scattering. (author)

  20. Neural network determination of parton distributions: the nonsinglet case

    International Nuclear Information System (INIS)

    Del Debbio, Luigi; Forte, Stefano; Latorre, Jose I.; Piccione, Andrea; Rojo, Joan

    2007-01-01

    We provide a determination of the isotriplet quark distribution from available deep-inelastic data using neural networks. We give a general introduction to the neural network approach to parton distributions, which provides a solution to the problem of constructing a faithful and unbiased probability distribution of parton densities based on available experimental information. We discuss in detail the techniques which are necessary in order to construct a Monte Carlo representation of the data, to construct and evolve neural parton distributions, and to train them in such a way that the correct statistical features of the data are reproduced. We present the results of the application of this method to the determination of the nonsinglet quark distribution up to next-to-next-to-leading order, and compare them with those obtained using other approaches

  1. What Exactly is a Parton Density ?

    International Nuclear Information System (INIS)

    Collins, J.C.

    2003-01-01

    I give an account of the definitions of parton densities, both the conventional ones, integrated over parton transverse momentum, and unintegrated transverse-momentum-dependent densities. The aim is to get a precise and correct definition of a parton density as the target expectation value of a suitable quantum mechanical operator, so that a clear connection to non-perturbative QCD is provided. Starting from the intuitive ideas in the parton model that predate QCD, we will see how the simplest operator definitions suffer from divergences. Corrections to the definition are needed to eliminate the divergences. An improved definition of unintegrated parton densities is proposed. (author)

  2. Calculation of parton fragmentation functions from jet calculus: gluon applications

    International Nuclear Information System (INIS)

    Lassila, K.E.; Ng, A.

    1985-01-01

    A method is presented for calculation of general parton fragmentation functions based on jet calculus plus meson and baryon wave functions. Results for gluon fragmentation into mesons and baryons are discussed and related to recent information on upsilon decay into gluons. The expressions derived can be used directly in e + e - cross section predictions and will need to be folded in with baryon parton distribution functions when used in p-barp collisions. (author)

  3. Multiple Parton Interactions in p$bar{p}$ Collisions in D0 Experiment at the Tevatron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Golovanov, Georgy [Joint Inst. for Nuclear Research (JINR), Dubna (Russia)

    2016-01-01

    The thesis is devoted to the study of processes with multiple parton interactions (MPI) in a ppbar collision collected by D0 detector at the Fermilab Tevatron collider at sqrt(s) = 1.96 TeV. The study includes measurements of MPI event fraction and effective cross section, a process-independent parameter related to the effective interaction region inside the nucleon. The measurements are done using events with a photon and three hadronic jets in the final state. The measured effective cross section is used to estimate background from MPI for WH production at the Tevatron energy

  4. Lower bounds for ν and Q2 values leading to scaling in the simple parton model

    International Nuclear Information System (INIS)

    Nataf, R.S.

    1979-06-01

    The simple parton model leads to the Bjorken scaling law only for rather large values of the transfer. For small values, the scale invariance is broken by a purely kinematical effect which is shown to depend on: (1+(4M 2 x 2 /Q 2 ))sup(1/2)-1, M being the mass of the target nucleon. Thus, one has to consider: ν>=5M (5GeV) and: Q 2 >=10M 2 x (9GeV/c) 2 for the whole x range) if it is demanded that scaling holds within 10% to error

  5. 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.

  6. Phenomenological study of the nucleon structure functions; Etude phenomenologique des fonctions de structure du nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Bertini, M

    1995-05-12

    This thesis is devoted to the study of the deep inelastic scattering. Its purpose is the development of phenomenological models describing experimental results on unpolarized (F{sub 2}) and polarized (g{sub 1}) nucleon structure functions in the wide range of the kinematical domain. Special attention is paid to the small-x behaviour of F{sub 2} and to the link between deep inelastic scattering and photoproduction process. The investigation of the Pomeron in deep inelastic scattering shows that one single Pomeron compatible with the Froissard-Martin limit can account for all the present HERA data. A phenomenological model of the proton structure function is developed, based on a two-component structure including various features expected from both perturbative quantum chromodynamics and non perturbative Regge theory. A link with the photoproduction process is provided. A detailed analysis of the perturbative components, based on the Gribov-Lipatov-Altarelli-Parisi evolution equations is presented. Taking into account the different parton distribution, this approach allows to describe data on proton and neutron structure functions, on deep inelastic neutrino scattering, and to reproduce the gluons distribution extracted by the ZEUS collaboration. The model is applied to the polarized deep inelastic scattering and the axial anomaly effect appearing both in the description of results on the spin dependent structure functions g{sup p,n,d} and in the interpretation of the nucleon spin structure is discussed. (J.S.). 260 refs., 34 figs., 8 tabs., 6 appends.

  7. Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering

    Energy Technology Data Exchange (ETDEWEB)

    Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman; Christian Weiss

    2007-03-01

    We propose a new approach to the problem of rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp-->p + (gap) + H + (gap) + p. It is based on the idea that hard and soft interactions proceed over widely different time- and distance scales and are thus approximately independent. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons. Its amplitude is calculable in terms of the gluon generalized parton distributions (GPDs) in the protons, which can be measured in J= production in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate in a model-independent way in terms of the pp elastic scattering amplitude. Contributions from inelastic intermediate states are suppressed. A simple geometric picture of the interplay of hard and soft interactions in diffraction is obtained. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton, or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons (''diffraction pattern''). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the LHC.

  8. Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering

    International Nuclear Information System (INIS)

    Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman; Christian Weiss

    2006-01-01

    We propose a new approach to the problem of rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp-->p + (gap) + H + (gap) + p. It is based on the idea that hard and soft interactions proceed over widely different time- and distance scales and are thus approximately independent. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons. Its amplitude is calculable in terms of the gluon generalized parton distributions (GPDs) in the protons, which can be measured in J= production in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate in a model-independent way in terms of the pp elastic scattering amplitude. Contributions from inelastic intermediate states are suppressed. A simple geometric picture of the interplay of hard and soft interactions in diffraction is obtained. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton, or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons (''diffraction pattern''). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the LHC

  9. Consequences of the factorization hypothesis in nucleon-nucleon, $\\gamma p and \\gamma \\gamma$ scattering

    CERN Document Server

    Block, Martin M

    2002-01-01

    Using an eikonal structure for the scattering amplitude, factorization theorems for nucleon-nucleon, gamma p and gamma gamma scattering at high energies have been derived, using only some very general assumptions. Using a QCD-inspired eikonal analysis of nucleon-nucleon scattering, we present here experimental confirmation for factorization of cross sections, nuclear slope parameters B and rho -values (ratio of real to imaginary portion of forward scattering amplitudes), showing that: 1) the three factorization theorems of Block and Kaidalov [2000] hold, 2) the additive quark model holds to approximately=1%, and 3) vector dominance holds to better than approximately=4%. Predictions for the total cross section, elastic cross section and other forward scattering parameters at the LHC (14 TeV) are given. (12 refs).

  10. The partonic nature of instantons

    International Nuclear Information System (INIS)

    Collie, Benjamin; Tong, David

    2009-01-01

    In both Yang-Mills theories and sigma models, instantons are endowed with degrees of freedom associated to their scale size and orientation. It has long been conjectured that these degrees of freedom have a dual interpretation as the positions of partonic constituents of the instanton. These conjectures are usually framed in d = 3+1 and d = 1+1 dimensions respectively where the partons are supposed to be responsible for confinement and other strong coupling phenomena. We revisit this partonic interpretation of instantons in the context of d = 4+1 and d = 2+1 dimensions. Here the instantons are particle-like solitons and the theories are non-renormalizable. We present an explicit and calculable model in d = 2+1 dimensions where the single soliton in the CP N sigma-model can be shown to be a multi-particle state whose partons are identified with the ultra-violet degrees of freedom which render the theory well-defined at high energies. We introduce a number of methods which reveal the partons inside the soliton, including deforming the sigma model and a dual version of the Bogomolnyi equations. We conjecture that partons inside Yang-Mills instantons hold the key to understanding the ultra-violet completion of five-dimensional gauge theories.

  11. Jets in high energy nucleon-nucleon collisions

    International Nuclear Information System (INIS)

    Strugalski, Z.

    1982-01-01

    From the experimental studies of high-energy hardon-nucleon and nucleon-nucleon collisions, by means of nuclear targets applied as detectors, it follows that particles are produced via intermediate objects created first in a 2 → 2 type endoergic reaction. These objects, called generons, decay in flight into finally observed particles and resonances after their lifetime tausub(g) > or approximately 10 - 22 s. The jet structure of the outcome in nucleon-nucleon collisions is a simple and indispensable consequence of this particle production mechanism. The picture of the jet structure in the collision outcome observed in the CMS of the colliding nucleons depends on the energy of these nUcleons. New particle production scheme is proposed, which can be tested experimentally; corresponding simple relations between characteristics of colliding nucleons and of produced jets are proposed for a testing

  12. Lattice QCD Calculation of Nucleon Structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Keh-Fei [University of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy; Draper, Terrence [University of Kentucky, Lexington, KY (United States). Dept. of Physics and Astronomy

    2016-08-30

    It is emphasized in the 2015 NSAC Long Range Plan that "understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics." Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out first-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large-scale computer simulation. We started out by calculating the nucleon form factors -- electromagnetic, axial-vector, πNN, and scalar form factors, the quark spin contribution to the proton spin, the strangeness magnetic moment, the quark orbital angular momentum, the quark momentum fraction, and the quark and glue decomposition of the proton momentum and angular momentum. The first round of calculations were done with Wilson fermions in the `quenched' approximation where the dynamical effects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge configurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at ~ 300 MeV and obtained the strange form factors, charm and strange quark masses, the charmonium spectrum and the Ds meson decay constant fDs, the strangeness and charmness, the meson mass

  13. Nucleon-nucleon scattering in the functional quantum theory of the nonlinear spinor field

    International Nuclear Information System (INIS)

    Haegele, G.

    1979-01-01

    The author calculates the S matrix for the elastic nucleon-nucleon scattering in the lowest approximation using the quantum theory of nonlinear spinor fields with special emphasis to the ghost configuration of this theory. Introducing a general scalar product a new functional channel calculus is considered. From the results the R and T matrix elements and the differential and integral cross sections are derived. (HSI)

  14. 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.)

  15. Pion and kaon valence-quark parton quasidistributions

    Science.gov (United States)

    Xu, Shu-Sheng; Chang, Lei; Roberts, Craig D.; Zong, Hong-Shi

    2018-05-01

    Algebraic Ansätze for the Poincaré-covariant Bethe-Salpeter wave functions of the pion and kaon are used to calculate their light-front wave functions, parton distribution amplitudes, parton quasidistribution amplitudes, valence parton distribution functions, and parton quasidistribution functions (PqDFs). The light-front wave functions are broad, concave functions, and the scale of flavor-symmetry violation in the kaon is roughly 15%, being set by the ratio of emergent masses in the s - and u -quark sectors. Parton quasidistribution amplitudes computed with longitudinal momentum Pz=1.75 GeV provide a semiquantitatively accurate representation of the objective parton distribution amplitude, but even with Pz=3 GeV , they cannot provide information about this amplitude's end point behavior. On the valence-quark domain, similar outcomes characterize PqDFs. In this connection, however, the ratio of kaon-to-pion u -quark PqDFs is found to provide a good approximation to the true parton distribution function ratio on 0.4 ≲x ≲0.8 , suggesting that with existing resources computations of ratios of parton quasidistributions can yield results that support empirical comparison.

  16. Studying the information content of TMDs using Monte Carlo generators

    Energy Technology Data Exchange (ETDEWEB)

    Avakian, H. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Matevosyan, H. [The Univ. of Adelaide, Adelaide (Australia); Pasquini, B. [Univ. of Pavia, Pavia (Italy); Schweitzer, P. [Univ. of Connecticut, Storrs, CT (United States)

    2015-02-05

    Theoretical advances in studies of the nucleon structure have been spurred by recent measurements of spin and/or azimuthal asymmetries worldwide. One of the main challenges still remaining is the extraction of the parton distribution functions, generalized to describe transverse momentum and spatial distributions of partons from these observables with no or minimal model dependence. In this topical review we present the latest developments in the field with emphasis on requirements for Monte Carlo event generators, indispensable for studies of the complex 3D nucleon structure, and discuss examples of possible applications.

  17. On the universality of the x and A dependence of the EMC effect and its relation to parton distributions in nuclei

    International Nuclear Information System (INIS)

    Smirnov, G.I.

    1995-01-01

    It is shown that the latest results from the NMC (CERN) and E665 (Fermilab) groups on F 2 A (x)/F 2 D (x) obtained in the shadowing region bring new evidence of the universal A dependence of distortions made in a free-nucleon structure function by a nuclear medium. The observed universality implies that one can consider separately hard (A≤4) and soft (A>4) parton distribution distortions. Soft distortions, which result in differences between the deep-inelastic scattering cross sections for nuclei with masses A 1 , A 2 ≥4, can be explained as a consequence of the nuclear density variation, independent of x in the range 0.001 ≤ x ≤ 0.7. It is found that nuclear shadowing begins at x 1 = 0.0615 ± 0.0024, independent of A, which is consistent with models that allow for three-parton recombination processes. 28 refs., 2 figs

  18. Effect of two-pion exchange in nucleon-nucleon scattering in high partial waves

    International Nuclear Information System (INIS)

    Harun ar Rashid, A.M.; Chaudhury, T.K.

    1983-01-01

    The work of Brown and Durso (Phys. Lett. 35B, 120 (1971)) on the soft-pion determination of the intermediate range nucleon-nucleon interaction is extended by using the most general form of the ΔNπ interaction which involves an arbitrary parameter Z. It is shown that both the annihilation channel helicity amplitude fsub(+)sup((O))(t) as well as peripheral proton-proton scattering phase shifts seem to favour Z=1/2. (author)

  19. Matching fully differential NNLO calculations and parton showers

    International Nuclear Information System (INIS)

    Alioli, Simone; Bauer, Christian W.; Berggren, Calvin; Walsh, Jonathan R.; Zuberi, Saba

    2013-11-01

    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.

  20. Structure and spin of the nucleon

    Directory of Open Access Journals (Sweden)

    Avakian H.

    2014-03-01

    Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs in semi-inclusive and hard exclusive processes providing access to TMDs and GPDs, respectively. Facilities world-wide involved in studies of the 3D structure of nucleon include HERMES, COMPASS, BELLE, BaBar, Halls A, B, and C at JLab, and PHENIX and STAR at RHIC (BNL. TMD studies in the Drell-Yan process are also becoming an important part of the program of hadron scattering experiments. Studies of TMDs are also among the main driving forces of the JLab 12-GeV upgrade project, several of the forward upgrade proposals of STAR and PHENIX at RHIC, and future facilities, such as the Electron Ion Collider (EIC, FAIR in Germany, and NICA in Russia. In this contribution we present an overview of the latest developments in studies of parton distributions and discuss newly released results, ongoing activities, as well as some future measurements.

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

    International Nuclear Information System (INIS)

    Müller, D.; Polyakov, M.V.; Semenov-Tian-Shansky, K.M.

    2015-01-01

    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 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 Kumerički-Müller GPD model to the dual parametrization framework by presenting the set of the corresponding forward-like functions. We also build up the reparametrization procedure allowing to recast the double distribution representation of GPDs in the Mellin-Barnes integral framework and present the explicit formula for mapping double distributions into the space of double partial wave amplitudes with complex conformal spin.

  2. Microscopic nucleon spectral function for finite nuclei featuring two- and three-nucleon short-range correlations: The model versus ab initio calculations for three-nucleon systems

    Science.gov (United States)

    Ciofi degli Atti, Claudio; Mezzetti, Chiara Benedetta; Morita, Hiko

    2017-04-01

    Background: Two-nucleon (2 N ) short-range correlations (SRC) in nuclei have been recently thoroughly investigated, both theoretically and experimentally and the study of three-nucleon (3 N ) SRC, which could provide important information on short-range hadronic structure, is underway. Novel theoretical ideas concerning 2 N and 3 N SRC are put forward in the present paper. Purpose: The general features of a microscopic one-nucleon spectral function which includes the effects of both 2 N and 3 N SRC and its comparison with ab initio spectral functions of the three-nucleon systems are illustrated. Methods: A microscopic and parameter-free one-nucleon spectral function expressed in terms of a convolution integral involving ab initio relative and center-of-mass (c.m.) momentum distributions of a 2 N pair and aimed at describing two- and three-nucleon short-range correlations, is obtained by using: (i) the two-nucleon momentum distributions obtained within ab initio approaches based upon nucleon-nucleon interactions of the Argonne family; (ii) the exact relation between one- and two-nucleon momentum distributions; (iii) the fundamental property of factorization of the nuclear wave function at short internucleon ranges. Results: The comparison between the ab initio spectral function of 3He and the one based upon the convolution integral shows that when the latter contains only two-nucleon short-range correlations the removal energy location of the peaks and the region around them exhibited by the ab initio spectral function are correctly predicted, unlike the case of the high and low removal energy tails; the inclusion of the effects of three-nucleon correlations brings the convolution model spectral function in much better agreement with the ab initio one; it is also found that whereas the three-nucleon short-range correlations dominate the high energy removal energy tail of the spectral function, their effects on the one-nucleon momentum distribution are almost one

  3. Sum rules across the unpolarized Compton processes involving generalized polarizabilities and moments of nucleon structure functions

    Science.gov (United States)

    Lensky, Vadim; Hagelstein, Franziska; Pascalutsa, Vladimir; Vanderhaeghen, Marc

    2018-04-01

    We derive two new sum rules for the unpolarized doubly virtual Compton scattering process on a nucleon, which establish novel low-Q2 relations involving the nucleon's generalized polarizabilities and moments of the nucleon's unpolarized structure functions F1(x ,Q2) and F2(x ,Q2). These relations facilitate the determination of some structure constants which can only be accessed in off-forward doubly virtual Compton scattering, not experimentally accessible at present. We perform an empirical determination for the proton and compare our results with a next-to-leading-order chiral perturbation theory prediction. We also show how these relations may be useful for a model-independent determination of the low-Q2 subtraction function in the Compton amplitude, which enters the two-photon-exchange contribution to the Lamb shift of (muonic) hydrogen. An explicit calculation of the Δ (1232 )-resonance contribution to the muonic-hydrogen 2 P -2 S Lamb shift yields -1 ±1 μ eV , confirming the previously conjectured smallness of this effect.

  4. Measurement of the LIght Quark Flavor Asymmetry in the Nucleon Sea

    International Nuclear Information System (INIS)

    Peng, J.C.; Awes, T.C.; Beddo, M.E.; Brooks, M.L.; Brown, C.N.; Bush, J.D.; Carey, T.A.; Chang, T.H.; Cooper, W.E.; Gagliardi, C.A.; Garvey, G.T.; Geesaman, D.F.; Hawker, E.A.; He, X.C.; Isenhower, L.D.; Kaufman, S.B.; Kaplan, D.M.; Kirk, P.N.; Koetke, D.D.; Kyle, G.; Lee, D.M.; Lee, W.M.; Leitch, M.J.; Makins, N.; McGaughey, P.L.; Moss, J.M.; Mueller, B.A.; Nord, P.M.; Park, B.K.; Papavassiliou, V.; Petitt, G.; Reimer, P.E.; Sadler, M.E.; Stankus, P.W.; Sondheim, W.E.; Thompson, T.N.; Towell, R.S.; Tribble, R.E.; Vasiliev, M.A.; Wang, Y.C.; Wang, Z.F.; Webb, J.C.; Willis, J.L.; Wise, D.K.; Young, G.R.

    1998-01-01

    The Drell-Yan cross section ratios, s(p+d)/s(p+p), measured in Fermilab E866, have led to the first determination of d(x)/u(x), d(x)-(x), and the integral of d(x)-u(x) for the proton over the range 0.02 < x < 0.345. The E866 results are compared with predictions based on parton distribution functions and various theoretical models. The relationship between the E866 results and the NMC measurements of the Gottfried integral is discussed. The agreement between the E866 results and models employing virtual mesons indicates these non-perturbative processes play an important role in the origin of the d, u asymmetry in the nucleon sea

  5. The lowest order total electromagnetic correction to the deep inelastic scattering of polarized leptons on polarized nucleons

    International Nuclear Information System (INIS)

    Shumeiko, N.M.; Timoshin, S.I.

    1991-01-01

    Compact formulae for a total 1-loop electromagnetic corrections, including the contribution of electromagnetic hadron effects to the deep inelastic scattering of polarized leptons on polarized nucleons in the quark-parton model have been obtained. The cases of longitudinal and transverse nucleon polarization are considered in detail. A thorough numerical calculation of corrections to cross sections and polarization asymmetries at muon (electron) energies over the range of 200-2000 GeV (10-16 GeV) has been made. It has been established that the contribution of corrections to the hadron current considerably affects the behaviour of longitudinal asymmetry. A satisfactory agreement is found between the model calculations of corrections to the lepton current and the phenomenological calculation results, which makes it possible to find the total 1-loop correction within the framework of a common approach. (Author)

  6. Parton distributions beyond the leading order

    International Nuclear Information System (INIS)

    Chyla, J.

    1993-01-01

    The importance of properly taking into account the factorization scheme dependence of parton distribution functions is emphasized. A serious error in the usual handling of this topic is pointed out and the correct procedure for transforming parton distribution functions from one factorization scheme to another recalled. It is shown that the conventional M bar S and DIS definitions thereof are ill defined due to the lack of distinction between the factorization scheme dependence of parton distribution functions and renormalization scheme dependence of the strong coupling constant α s . A novel definition of parton distribution functions is suggested and its role in the construction of consistent next-to-leading-order event generators briefly outlined

  7. Studies of high energy lepton-nucleon scattering

    International Nuclear Information System (INIS)

    Ingelman, G.

    1982-05-01

    The first part of this thesis is related to the problem of detecting charmed particles. A new technique for observing very short decay paths in nuclear emulsions is developed and applied on a sample of neutrino induced reactions. Techniques for producing thick pellicles of nuclear track emulsion are also developed. In the second part, phenomenological investigations of deep inelastic lepton-nucleon scattering are made. Monte Carlo computer programs, based on the parton model and perturbative QCD for the initial hard process and the Lund model for the following soft hadronization, are used to simulate these reactions and thereby obtain explicit results. Generally good agreement is found when comparing these with experimental data, thus supporting this basic framework. Predictions to test QCD are made. Transverse momentum properties are studied in detail, in particular effects from soft gluon emission. The properties of a model for baryon production, both from the target remnant and the colour force field, are discussed and the results found to agree with data. It is shown that, at the presently available energies, the observable energy flow is not due to QCD, but arises from the baryon production in the target fragmentation. In a model to explain the observed Λ polarization, a connection between the confinement of quarks and these polarization phenomena is suggested. (Auth.)

  8. Partons and quarks. Daresbury lecture note series No. 12

    Energy Technology Data Exchange (ETDEWEB)

    Close, F. E.

    1973-04-15

    The report is based on a series of lectures given at Daresbury Laboratory on 2 to 12 Apri1 1973. It is stated that the purpose was to show the reasons why parton models describe the data, show what other phenomena can be understood and what predictions can be made within the parton hypothesis. The report is in sections: elastic electron scattering; inelastic electron scattering; deep inelastic scattering and partons; structure functions and surn rules in the quark parton model; inelastic neutrinto scattering; forward Compton scattering; Compton scattering in simple models; a J = 0 fixed pole in Compton scattering; the non-perturbative parton model without tears; the parton model and vector-meson dominance-rivals or partners; do resonances scale; resonances, SU(6) and the quark parton model; towards a dynamical parton model. (UK)

  9. The study of production processes of nucleons, γ-quanta and neutral strange particles in pp- and pn-interactions at 300 GeV

    International Nuclear Information System (INIS)

    Turumov, Eh.

    2001-03-01

    Processes of nucleons, γ-quanta and neutral strange particles in pp- and pn-interactions at 300 GeV in 4π-geometry were studied by the use of neon-hydrogen bubble chamber. The average multiplicity of γ-quanta, fast neutrons, K 0 s -mesons and λ 0 ( λ 0 bar)-hyperons were defined and their energy spectra were analyzed. Experimental results were compared with Lund and dual parton model predictions. (author)

  10. Parton Distributions Working Group

    International Nuclear Information System (INIS)

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

    2000-01-01

    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

  11. Imaging partons in exclusive scattering processes

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus

    2012-06-15

    The spatial distribution of partons in the proton can be probed in suitable exclusive scattering processes. I report on recent performance estimates for parton imaging at a proposed Electron-Ion Collider.

  12. When is a heavy quark not a parton? Charged Higgs production and heavy quark mass effects in the QCD-based parton model

    International Nuclear Information System (INIS)

    Olness, F.I.; Tung, Wu-Ki

    1989-10-01

    Applications of the QCD-based parton model to new physics processes involving heavy partons are illustrated using charged Higgs production. The naive parton model predictions are found to over-estimate the actual cross section by a factor of 2 to 5. The role of the top quark as a ''parton'' is examined, and the energy range over which heavy quarks (or other particles) should or should not be naturally treated as ''partons'' is delineated. 12 refs., 5 figs

  13. 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.

  14. The effect of higher order different meson exchange nucleon-nucleon interactions on the three-nucleon binding energy coupling problem

    International Nuclear Information System (INIS)

    Osman, A.; Ramadan, S.

    1989-01-01

    Faddeev equations of bound three-nucleon system are presented as a set of integral equations. To solve them, a sutable form of the nucleon-nucleon interactions is used: with the exchange of a scalar meson, a pseudoscalar meson and a massless vector meson. Higher orders of these different meson exchanges in the nucleon-nucleon interactions have been taken into account. With these nuclear forces and nucleon-nucleon interactions, the three-nucleon binding energy is calculated by solving the Faddeev integral equations. The obtained value of the three-nucleon binding energy is 8.441 MeV. The inclusion of the higher order terms of the different meson exchange in the nuclear nucleon-nucleon interaction is found to affect the three-nucleon binding by about 3.92%. 3 figs., 16 refs

  15. Parton distributions with QED corrections

    NARCIS (Netherlands)

    Collaboration, The NNPDF; Ball, Richard D.; Bertone, Valerio; Carrazza, Stefano; Debbio, Luigi Del; Forte, Stefano; Guffanti, Alberto; Hartland, Nathan P.; Rojo, Juan

    2013-01-01

    We present a set of parton distribution functions (PDFs), based on the NNPDF2.3 set, which includes a photon PDF, and QED contributions to parton evolution. We describe the implementation of the combined QCD+QED evolution in the NNPDF framework. We then provide a first determination of the full set

  16. Analytic solutions of QCD evolution equations for parton cascades inside nuclear matter at small x

    International Nuclear Information System (INIS)

    Geiger, K.

    1994-01-01

    An analytical method is presented to solve generalized QCD evolution equations for the time development of parton cascades in a nuclear environment. In addition to the usual parton branching processes in vacuum, these evolution equations provide a consistent description of interactions with the nuclear medium by accounting for stimulated branching processes, fusion, and scattering processes that are specific to QCD in a medium. Closed solutions for the spectra of produced partons with respect to the variables time, longitudinal momentum, and virtuality are obtained under some idealizing assumptions about the composition of the nuclear medium. Several characteristic features of the resulting parton distributions are discussed. One of the main conclusions is that the evolution of a parton shower in a medium is dilated as compared to free space and is accompanied by an enhancement of particle production. These effects become stronger with increasing nuclear density

  17. Summing threshold logs in a parton shower

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2016-05-01

    When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in α 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.

  18. Are Parton Distributions Positive?

    CERN Document Server

    Forte, Stefano; Ridolfi, Giovanni; Altarelli, Guido; Forte, Stefano; Ridolfi, Giovanni

    1999-01-01

    We show that the naive positivity conditions on polarized parton distributions which follow from their probabilistic interpretation in the naive parton model are reproduced in perturbative QCD at the leading log level if the quark and gluon distribution are defined in terms of physical processes. We show how these conditions are modified at the next-to-leading level, and discuss their phenomenological implications, in particular in view of the determination of the polarized gluon distribution

  19. Are parton distributions positive?

    International Nuclear Information System (INIS)

    Forte, Stefano; Altarelli, Guido; Ridolfi, Giovanni

    1999-01-01

    We show that the naive positivity conditions on polarized parton distributions which follow from their probabilistic interpretation in the naive parton model are reproduced in perturbative QCD at the leading log level if the quark and gluon distribution are defined in terms of physical processes. We show how these conditions are modified at the next-to-leading level, and discuss their phenomenological implications, in particular in view of the determination of the polarized gluon distribution

  20. The effect of including tensor forces in nucleon-nucleon interaction on three-nucleon binding energy

    International Nuclear Information System (INIS)

    Osman, A.; Ramadan, S.

    1986-01-01

    Separable two-body interactions are used in considering the three-nucleon problem. The nucleon-nucleon potentials are taken to include attraction and repulsion as well as tensor forces. The separable approximation is used in order to investigate the effect of the tensor forces. The separable expansion is introduced in the three-nucleon problem, by which the Faddeev equations are reduced to a well-behaved set of coupled integral equations. Numerical calculations are carried out for the obtained integral equations using potential functions of the Yamaguchi, Gaussian, Takabin, Mongan and Reid forms. The present calculated values of the binding energies of the 3 H and 3 He nuclei are in good agreement with the experimental values. The effect of including the tensor forces in the nucleon-nucleon interactions is found to improve the three-nucleon binding energy by about 4.490% to 8.324%. 37 refs., 2 tabs. (author)

  1. 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.

  2. Correlations in double parton distributions. Effects of evolution

    International Nuclear Information System (INIS)

    Diehl, Markus; Keane, Shane; Kasemets, Tomas; Vrije Univ., Amsterdam

    2014-01-01

    We numerically investigate the impact of scale evolution on double parton distributions, which are needed to compute multiple hard scattering processes. Assuming correlations between longitudinal and transverse variables or between the parton spins to be present at a low scale, we study how they are affected by evolution to higher scales, i.e. by repeated parton emission. We find that generically evolution tends to wash out correlations, but with a speed that may be slow or fast depending on kinematics and on the type of correlation. Nontrivial parton correlations may hence persist in double parton distributions at the high scales relevant for hard scattering processes.

  3. Chiral dynamics and partonic structure at large transverse distances

    Energy Technology Data Exchange (ETDEWEB)

    Strikman, M. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Physics; Weiss, C. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States). Theory Center

    2009-12-30

    In this paper, we study large-distance contributions to the nucleon’s parton densities in the transverse coordinate (impact parameter) representation based on generalized parton distributions (GPDs). Chiral dynamics generates a distinct component of the partonic structure, located at momentum fractions x≲Mπ/MN and transverse distances b~1/Mπ. We calculate this component using phenomenological pion exchange with a physical lower limit in b (the transverse “core” radius estimated from the nucleon’s axial form factor, Rcore=0.55 fm) and demonstrate its universal character. This formulation preserves the basic picture of the “pion cloud” model of the nucleon’s sea quark distributions, while restricting its application to the region actually governed by chiral dynamics. It is found that (a) the large-distance component accounts for only ~1/3 of the measured antiquark flavor asymmetry d¯-u¯ at x~0.1; (b) the strange sea quarks s and s¯ are significantly more localized than the light antiquark sea; (c) the nucleon’s singlet quark size for x<0.1 is larger than its gluonic size, (b2)q+q¯>(b2)g, as suggested by the t-slopes of deeply-virtual Compton scattering and exclusive J/ψ production measured at HERA and FNAL. We show that our approach reproduces the general Nc-scaling of parton densities in QCD, thanks to the degeneracy of N and Δ intermediate states in the large-Nc limit. Finally, we also comment on the role of pionic configurations at large longitudinal distances and the limits of their applicability at small x.

  4. Summing threshold logs in a parton shower

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Zoltán [DESY,Notkestrasse 85, 22607 Hamburg (Germany); Soper, Davison E. [Institute of Theoretical Science, University of Oregon,Eugene, OR 97403-5203 (United States)

    2016-10-05

    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.

  5. Nucleon structure by Lattice QCD computations with twisted mass fermions

    International Nuclear Information System (INIS)

    Harraud, P.A.

    2010-11-01

    Understanding the structure of the nucleon from quantum chromodynamics (QCD) is one of the greatest challenges of hadronic physics. Only lattice QCD allows to determine numerically the values of the observables from ab-initio principles. This thesis aims to study the nucleon form factors and the first moments of partons distribution functions by using a discretized action with twisted mass fermions. As main advantage, the discretization effects are suppressed at first order in the lattice spacing. In addition, the set of simulations allows a good control of the systematical errors. After reviewing the computation techniques, the results obtained for a wide range of parameters are presented, with lattice spacings varying from 0.0056 fm to 0.089 fm, spatial volumes from 2.1 up to 2.7 fm and several pion masses in the range of 260-470 MeV. The vector renormalization constant was determined in the nucleon sector with improved precision. Concerning the electric charge radius, we found a finite volume effect that provides a key towards an explanation of the chiral dependence of the physical point. The results for the magnetic moment, the axial charge, the magnetic and axial charge radii, the momentum and spin fractions carried by the quarks show no dependence on the lattice spacing nor volume. In our range of pion masses, their values show a deviation from the experimental values. Their chiral behaviour do not exhibit the curvature predicted by the chiral perturbation theory which could explain the apparent discrepancy. (author)

  6. Structure of rapidity divergences in multi-parton scattering soft factors

    Science.gov (United States)

    Vladimirov, Alexey

    2018-04-01

    We discuss the structure of rapidity divergences that are presented in the soft factors of transverse momentum dependent (TMD) factorization theorems. To provide the discussion on the most general level we consider soft factors for multi-parton scattering. We show that the rapidity divergences are result of the gluon exchanges with the distant transverse plane, and are structurally equivalent to the ultraviolet divergences. It allows to formulate and to prove the renormalization theorem for rapidity divergences. The proof is made with the help the conformal transformation which maps rapidity divergences to ultraviolet divergences. The theorem is the systematic form of the factorization of rapidity divergences, which is required for the definition of TMD parton distributions. In particular, the definition of multi parton distributions is presented. The equivalence of ultraviolet and rapidity divergences leads to the exact relation between soft and rapidity anomalous dimensions. Using this relation we derive the rapidity anomalous dimension at the three-loop order.

  7. Framework for evolution in double parton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Buffing, Maarten G.A.

    2017-07-15

    Double parton scattering (DPS) describes two colliding hadrons having interactions in the form of two hard processes, each initiated by a separate pair of partons. Just as for single parton scattering, the resummation of soft gluon exchange gives rise to a soft function, which is a necessary ingredient for obtaining rapidity evolution equations. For various regions of phase space, we derive the rapidity evolution and the scale evolution of double transverse momentum dependent parton distribution functions (DTMDs) as well as of the p{sub T}-resummed cross section for double Drell-Yan like processes. This contributes to a framework that can be used for phenomenological DPS studies including resummation.

  8. Parity violation in the nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Haxton, W.C.

    1989-01-01

    I discuss the present status of our understanding of parity nonconservation (PNC) in the nucleon-nucleon interaction, and some of the difficulties inherent in nuclear tests of PNC. I also discuss the nucleon/nuclear anapole moment, the parity violating coupling of the photon, and its relation to the PNC NN interaction. 13 refs., 1 fig., 2 tabs

  9. An analytic initial-state parton shower

    International Nuclear Information System (INIS)

    Kilian, W.

    2011-12-01

    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.)

  10. 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.)

  11. Constraints on parton density functions from D0

    Energy Technology Data Exchange (ETDEWEB)

    Hays, Jonathan M.; /Imperial Coll., London

    2008-04-01

    Five recent results from D0 which either impact or have the potential to impact on uncertainties in parton density functions are presented. Many analyses at D0 are sensitive to the modeling of the partonic structure of the proton. When theoretical and experimental uncertainties are well controlled there exists the possibility for additional constraints on parton density functions (PDF). Five measurements are presented which either have already been included in global parton fits or have the potential to contribute in the future.

  12. Hadron seagulls and parton jets

    International Nuclear Information System (INIS)

    Satz, H.; Zarmi, Y.

    1976-01-01

    For the lepton production of hadrons in the current fragmentation region it was recently shown that the two-level partonic picture leads to a broadening of the average transverse momentum of the observed secondaries. This ''seagull'' effect is well known for hadron-hadron interactions. In the note it is considered the possibility that parton arguments can explain it here as well and it is discussed what information on the constituent structure of hadrons can be obtained through an investigation of the seagull effect from such a point of view. It is shown that a non trivial seagull effect is a consequence of a simple two step production mechanism and the parton model predicts significant differences between baryon, meson and virtual-photon fragmentation seagull

  13. New information on parton distributions

    International Nuclear Information System (INIS)

    Martin, A.D.; Stirling, W.J.; Roberts, R.G.

    1992-04-01

    New data on structure functions from deep-inelastic scattering provide new information on parton distributions, particularly in the 0.01 2 data from the New Muon Collaboration (NMC) and its implications for other processes, and the evidence for SU(2) symmetry breaking in the light quark sea. We show that although good fits can be obtained with or without this symmetry breaking, more physically reasonable parton distributions are obtained if we allow d-bar > u-bar at small x. With the inclusion of the latest deep-inelastic data we find α s (M Z ) = 0.111 -0.005 +0.004 . We also show how W, Z and Drell-Yan production at p-barp colliders can give information on parton distributions. (Author)

  14. Partons and their applications at high energies

    International Nuclear Information System (INIS)

    Drell, Sidney D.; Yan, Tung-Mow

    2000-01-01

    We discuss Feynman's parton model for deep inelastic weak or electromagnetic processes as an application of the impulse approximation to elementary particle interactions. The special features and conditions permitting this application are elaborated upon in some detail including the dependence of the parton model and the impulse treatment on an appropriate choice of coordinate frames and the role of the very soft or wee partons. Application of the parton model is made to the calculation of the cross section for massive lepton pair production in very high energy hadron-hadron collisions and compared with experiment. The conjectured role of light cone singularities in describing this and the other deep inelastic amplitudes is also discussed. (c) 2000 Academic Press, Inc

  15. Nucleon-nucleon theory and phenomenology. Progress report and renewal proposal

    International Nuclear Information System (INIS)

    Signell, P.

    1981-01-01

    Progress is outlined on five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction with the new dramatically altered ππ s-wave interaction and using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with significantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 MeV and the new data near 55 MeV that have never been analyzed properly, and determining which phases are given by theory at which energies; (4) the introduction of our K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated and verified permanent nucleon-nucleon data bank in the 0 to 1200 MeV range that can be used by all nucleon-nucleon researchers (or anyone else) via Telenet dial-in and by means of a published compendium

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

    International Nuclear Information System (INIS)

    Garzelli, M.V.; Moch, S.; Placakyte, R.; Sigl, G.; Cooper-Sarkar, A.

    2016-11-01

    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 collaboration.

  17. Isospin breaking in the pion-nucleon coupling constant and the nucleon-nucleon scattering length

    Directory of Open Access Journals (Sweden)

    V. A. Babenko

    2016-08-01

    Full Text Available Charge independence breaking (CIB in the pion-nucleon coupling constant and the nucleon-nucleon scattering length is considered on the basis of the Yukawa meson theory. CIB effect in these quantities is almost entirely explained by the mass difference between the charged and the neutral pions. Therewith charge splitting of the pion-nucleon coupling constant is almost the same as charge splitting of the pion mass. Calculated difference between the proton-proton and the neutron-proton scattering length in this case comprises ∼90% of the experimental value.

  18. Endpoint singularities in unintegrated parton distributions

    CERN Document Server

    Hautmann, F

    2007-01-01

    We examine the singular behavior from the endpoint region x -> 1 in parton distributions unintegrated in both longitudinal and transverse momenta. We identify and regularize the singularities by using the subtraction method, and compare this with the cut-off regularization method. The counterterms for the distributions with subtractive regularization are given in coordinate space by compact all-order expressions in terms of eikonal-line operators. We carry out an explicit calculation at one loop for the unintegrated quark distribution. We discuss the relation of the unintegrated parton distributions in subtractive regularization with the ordinary parton distributions.

  19. 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.

  20. 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.)

  1. An analytic parton shower. Algorithms, implementation and validation

    International Nuclear Information System (INIS)

    Schmidt, Sebastian

    2012-06-01

    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.)

  2. Three-nucleon forces

    International Nuclear Information System (INIS)

    Sauer, P.U.

    2014-01-01

    In this paper, the role of three-nucleon forces in ab initio calculations of nuclear systems is investigated. The difference between genuine and induced many-nucleon forces is emphasized. Induced forces arise in the process of solving the nuclear many-body problem as technical intermediaries toward calculationally converged results. Genuine forces make up the Hamiltonian. They represent the chosen underlying dynamics. The hierarchy of contributions arising from genuine two-, three- and many-nucleon forces is discussed. Signals for the need of the inclusion of genuine three-nucleon forces are studied in nuclear systems, technically best under control, especially in three-nucleon and four-nucleon systems. Genuine three-nucleon forces are important for details in the description of some observables. Their contributions to observables are small on the scale set by two-nucleon forces. (author)

  3. Semi-phenomenological model of the nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Houriet, A.; Bagnoud, Y.

    1977-01-01

    A nucleon with isobars is used to elaborate a model of the nucleon-nucleon interaction at low energy (Esub(CM) 2 sub(r), the pion-nucleon renormalized coupling constant. The model establishes a very good coordination for deuteron and p-p scattering-polarization measurements ( 1 K 0 , 1 D 2 , 1 G 4 phase shifts), and permits the determination of f 2 sub(r) for every independent experimental value. For 21 such values, the mean value 2 sub(r)>=0.0785 with Δf 2 sub(r)=0.0024(3%) is obtained. (Auth.)

  4. Coupled channels Marchenko inversion for nucleon-nucleon potentials

    International Nuclear Information System (INIS)

    Kohlhoff, H.; Geramb, H.V. von

    1994-01-01

    Marchenko inversion is used to determine local energy independent but channel dependent potential matrices from optimum sets of experimental phase shifts. 3 SD 1 and 3 PF 2 channels of nucleon-nucleon systems contain in their off-diagonal potential matrices explicitly the tensor force for T = 0 and 1 isospin. We obtain, together with single channels, complete sets of quantitative nucleon-nucleon potential results which are ready for application in nuclear structure and reaction analyses. The historic coupled channels inversion result of Newton and Fulton is revisited. (orig.)

  5. New results in the Dual Parton Model

    International Nuclear Information System (INIS)

    Van, J.T.T.; Capella, A.

    1984-01-01

    In this paper, the similarity between the x distribution for particle production and the fragmentation functions are observed in e+e- collisions and in deep inelastic scattering are presented. Based on the observation, the authors develop a complete approach to multiparticle production which incorporates the most important features and concepts learned about high energy collisions. 1. Topological expansion : the dominant diagram at high energy corresponds to the simplest topology. 2. Unitarity : diagrams of various topology contribute to the cross sections in a way that unitary is preserved. 3. Regge behaviour and Duality. 4. Partonic structure of hadrons. These general theoretical ideas, result from many joint experimental and theoretical efforts on the study of soft hadron physics. The dual parton model is able to explain all the experimental features from FNAL to SPS collider energies. It has all the properties of an S-matrix theory and provides a unified description of hadron-hadron, hadron-nucleus and nucleus-nucleus collisions

  6. Nucleon-nucleon forces in the quark compound bag model and few-nucleon systems

    International Nuclear Information System (INIS)

    Kalashnikova, Yu.S.; Narodetskij, I.M.

    1984-01-01

    Role of quark-gluon degrees of freedom is discussed in nucleon-nucleon scattering at low and intermediate energies. It is shown that the existence of six-quark hags fixes the form of NN potential at small distances, which leads to the P-matrix satisfying the criterion of Jaffe and Low. The dynamical model of three-nucleon system is discussed taking into accoint the contribution of six-quark bags

  7. Deep inelastic processes and the parton model

    International Nuclear Information System (INIS)

    Altarelli, G.

    The lecture was intended as an elementary introduction to the physics of deep inelastic phenomena from the point of view of theory. General formulae and facts concerning inclusive deep inelastic processes in the form: l+N→l'+hadrons (electroproduction, neutrino scattering) are first recalled. The deep inelastic annihilation e + e - →hadrons is then envisaged. The light cone approach, the parton model and their relation are mainly emphasized

  8. Parton Distribution Benchmarking with LHC Data

    NARCIS (Netherlands)

    Ball, Richard D.; Carrazza, Stefano; Debbio, Luigi Del; Forte, Stefano; Gao, Jun; Hartland, Nathan; Huston, Joey; Nadolsky, Pavel; Rojo, Juan; Stump, Daniel; Thorne, Robert S.; Yuan, C. -P.

    2012-01-01

    We present a detailed comparison of the most recent sets of NNLO PDFs from the ABM, CT, HERAPDF, MSTW and NNPDF collaborations. We compare parton distributions at low and high scales and parton luminosities relevant for LHC phenomenology. We study the PDF dependence of LHC benchmark inclusive cross

  9. Two-body Dirac equations for nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Liu Bin; Crater, Horace

    2003-01-01

    We investigate the nucleon-nucleon interaction by using the meson exchange model and the two-body Dirac equations of constraint dynamics. This approach to the two-body problem has been successfully tested for QED and QCD relativistic bound states. An important question we wish to address is whether or not the two-body nucleon-nucleon scattering problem can be reasonably described in this approach as well. This test involves a number of related problems. First we must reduce our two-body Dirac equations exactly to a Schroedinger-like equation in such a way that allows us to use techniques to solve them already developed for Schroedinger-like systems in nonrelativistic quantum mechanics. Related to this, we present a new derivation of Calogero's variable phase shift differential equation for coupled Schroedinger-like equations. Then we determine if the use of nine meson exchanges in our equations gives a reasonable fit to the experimental scattering phase shifts for n-p scattering. The data involve seven angular momentum states including the singlet states 1 S 0 , 1 P 1 , 1 D 2 and the triplet states 3 P 0 , 3 P 1 , 3 S 1 , 3 D 1 . Two models that we have tested give us a fairly good fit. The parameters obtained by fitting the n-p experimental scattering phase shift give a fairly good prediction for most of the p-p experimental scattering phase shifts examined (for the singlet states 1 S 0 , 1 D 2 and triplet states 3 P 0 , 3 P 1 ). Thus the two-body Dirac equations of constraint dynamics present us with a fit that encourages the exploration of a more realistic model. We outline generalizations of the meson exchange model for invariant potentials that may possibly improve the fit

  10. Deeply virtual compton scattering on the nucleon with the Clas Detector of Jefferson Lab: measurement of the polarized and unpolarized cross sections

    International Nuclear Information System (INIS)

    Jo, H.S.

    2007-03-01

    The Generalized Parton Distributions (GPDs), introduced in the 1990's, provide the most complete description of the structure (in quarks and gluons) of the nucleon. The Deeply Virtual Compton Scattering (DVCS), which corresponds to the 'hard' exclusive electroproduction of photons on the nucleon, is a key process among the reactions allowing access to the GPDs. A DVCS-dedicated experiment was carried out in 2005 with the CLAS detector of Jefferson Lab, using a polarized electron beam of 5.776 GeV and a hydrogen target. For this experiment, we built and used a dedicated electromagnetic calorimeter capable of detecting the final-state photon. The collected data allowed us to study the DVCS in the widest kinematic range ever accessed for this reaction: 1 2 2 , 0.1 B 2 . The work performed during this PhD includes simulation work done for the preparation of the experiment, timing calibration of one of the CLAS subsystems, and data analysis. The aim of the data analysis was the extraction of the unpolarized cross sections of the studied reaction and of the difference of the polarized cross sections, this latter observable being linearly proportional to the GPDs. The obtained results were compared to DVCS theoretical calculations based on one of the most up-to-date GPD parametrizations. (author)

  11. Search for Nucleon Decays in Super-Kamiokande

    International Nuclear Information System (INIS)

    Miura, Makoto

    2010-01-01

    Grand Unified Theories (GUTs) is motivated by merging of the coupling constants of the strong, weak, and electromagnetic forces at a large energy scale (∼10 16 GeV), which is out of the reach of accelerators. One of the other general features of GUTs is that they allow lepton and baryon number violations and they predict instability of nucleons. Then nucleon decay experiments are the direct probe for GUTs. The Super-Kamiokande (SK) is a water Cherenkov detector which keeps running to detect nucleon decays with large mass. There are no other nucleon decay detectors which have as long exposure as SK. The results of nucleon decay search based on 173 kton year (1996-2008) will be presented in the conference.The favored decay mode in GUTs based on SU(5) symmetry is p→e + π 0 . On the other hand, p→ν K + is favored by SUSY GUTs model. Those two modes will be mainly discussed. (authors)

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

    Science.gov (United States)

    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.; CLAS Collaboration

    2017-03-01

    The cross section of the exclusive η electroproduction reaction e p →e'p'η was measured at Jefferson Laboratory with a 5.75 GeV electron beam and the CLAS detector. Differential cross sections d4σ /d t d Q2d xBd ϕη and structure functions σU=σT+ɛ σL,σT T , and σL T, as functions of t , were obtained over a wide range of Q2 and xB. The η structure functions are compared with those previously measured for π0 at the same kinematics. At low t , both π0 and η are described reasonably well by generalized parton distributions (GPDs) in which chiral-odd transversity GPDs are dominant. The π0 and η data, when taken together, can facilitate the flavor decomposition of the transversity GPDs.

  13. Nucleon-nucleon momentum correlation function for light nuclei

    International Nuclear Information System (INIS)

    Ma, Y.G.; Cai, X.Z.; Chen, J.G.; Fang, D.Q.; Guo, W.; Liu, G.H.; Ma, C.W.; Ma, E.J.; Shen, W.Q.; Shi, Y.; Su, Q.M.; Tian, W.D.; Wang, H.W.; Wang, K.; Wei, Y.B.; Yan, T.Z.

    2007-01-01

    Nucleon-nucleon momentum correlation function have been presented for nuclear reactions with neutron-rich or proton-rich projectiles using a nuclear transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model. The relationship between the binding energy of projectiles and the strength of proton-neutron correlation function at small relative momentum has been explored, while proton-proton correlation function shows its sensitivity to the proton density distribution. Those results show that nucleon-nucleon correlation function is useful to reflect some features of the neutron- or proton-halo nuclei and therefore provide a potential tool for the studies of radioactive beam physics

  14. On the nucleon-nucleon potential obtained from non-linear coupling

    International Nuclear Information System (INIS)

    El Ghabaty, S.S.

    1975-07-01

    The static limit of a pseudoscalar symmetric meson theory of nuclear forces is examined. The Born-Oppenheimer potential is determined for the case of two very heavy nucleons exchanging pseudoscalar isovector pions with non-linear coupling. It is found that the non-linear terms induced by the γ 5 coupling are cancelled by the additional pion-nucleon coupling of the non-linear sigma model. The nucleon-nucleon potential thus obtained is the same as the Yukava potential except for strength at different separations between the two nucleons

  15. Nucleon quark structure and strong meson-nucleon form factors

    International Nuclear Information System (INIS)

    Efimov, G.V.; Ivanov, M.A.

    1987-01-01

    The nucleon is considered as a three-quark system in virton-quark model. The main statistic properties of proton and neutron are calculated: magnetic moments, electromagnetic radii, G A /G V ratio in weak neutron decay. Strong meson-nucleon form factors which determine nucleon-nucleon potential are obtained as a function of squared transfer momentum of mesons. The results are compared with phenomenological form factors used for description of phases of NN-scattering in the one-boson-, exchange model

  16. Pion-nucleon vertex function with one nucleon off shell

    International Nuclear Information System (INIS)

    Mizutani, T.; Rochus, P.

    1979-01-01

    The pion-nucleon vertex function with an off-mass-shell nucleon is obtained through sideways dispersion relations with the P 11 and S 11 pion-nucleon phase shifts as only input. Contrary to the recent calculation of Nutt and Shakin, we find that the proper and improper vertex functions behave quite differently, indicating the importance of the nucleon propagator dressing. In particular the proper vertex function is found to have two poles in the unphysical region

  17. Quark bags, P-matrix and nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Narodetskij, I.M.

    1984-01-01

    This paper is an extended version of the talk given at IX European Conference on Few Body Problems in Physics, Tbilisi, 1984. It reviews recent developments of the quark compound bag (QCB) model including explicit examples of the QCB nucleon-nucleon potentials, description of the deuteron properties, calculation of the six quark admixture in the deuteron and applications to the three-nucleon system

  18. On neutrino and antineutrino scattering by electrons, and by partons

    International Nuclear Information System (INIS)

    Bell, J.S.; Dass, G.V.

    1975-09-01

    Assuming a non-derivative point interaction, and Born approximation, there are some simple relations between neutrino and antineutrino scattering on electrons or partons. They have been observed already, for some special cases, in the results of explicit calculations. Here they are obtained from simple general considerations. (author)

  19. Investigation of the nucleon structure and the nucleon-nucleon interaction by electron-deuteron scattering

    International Nuclear Information System (INIS)

    Simon, G.G.

    1978-01-01

    In this thesis results of measurements of the differential cross sections of the elastic and inelastic electron deuteron scattering are presented. The data were taken at several scattering angles and in the electron energy range of 150 MeV up to 320 MeV. The extracted form factors and structure functions are compared with theoretical results which are sensitive to details of nucleon structure and of the nucleon-nucleon forces. (FKS)

  20. Probing of the isospin-dependent mean field and nucleon-nucleon cross section in a medium by nucleon emissions

    International Nuclear Information System (INIS)

    Liu Jianye; Xing Yongzhong; Guo Wenjun

    2003-01-01

    We study the isospin effects of the mean field and two-body collision on the nucleon emissions at the intermediate energy heavy-ion collisions by using an isospin-dependent transport theory. The calculated results show that the nucleon emission number N n depends sensitively on the isospin effect of nucleon-nucleon cross section and weakly on the isospin-dependent mean field for neutron-poor system in higher beam energy region. In particular, the correlation between the medium correction of two-body collision and the momentum-dependent interaction enhances the dependence of nucleon emission number N n on the isospin effect of nucleon-nucleon cross section. On the contrary, the ratio of the neutron-proton ratio of the gas phase to the neutron-proton ratio of the liquid phase, i.e., the degree of isospin fractionation [(N/Z) gas ] b /[(N/Z) liq ] b depends sensitively on the isospin-dependent mean field and weakly on the isospin effect of two-body collision for neutron-rich system in the lower beam energy region. In this case, N n and [(N/Z) gas ] b /[(N/Z) liq ] b are the probes for extracting the information about the isospin-dependent nucleon-nucleon cross section in the medium and the isospin-dependent mean field, respectively

  1. Parton-hadron cascade approach at SPS and RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Nara, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-07-01

    A parton-hadron cascade model which is the extension of hadronic cascade model incorporating hard partonic scattering based on HIJING is presented to describe the space-time evolution of parton/hadron system produced by ultra-relativistic nuclear collisions. Hadron yield, baryon stopping and transverse momentum distribution are calculated and compared with HIJING and VNI. Baryon density, energy density and temperature for RHIC are calculated within this model. (author)

  2. On neutrino and antineutrino scattering by electrons, and by partons

    CERN Document Server

    Bell, J S

    1975-01-01

    Assuming a non-derivative point interaction, and Born approximation, there are some simple relations between neutrino and antineutrino scattering on electrons or partons. They have been observed already, for some special cases, in the results of explicit calculations. Here they are obtained from simple and general considerations. (8 refs).

  3. On the sensitivity of nucleon-nucleon correlations to the form of short-range potential

    International Nuclear Information System (INIS)

    Gmitro, M.; Kvasil, J.; Lednicky, R.; Lyuboshitz, V.L.

    1986-01-01

    Nucleon-nucleon correlation characteristics are calculated for several phenomenological and realistic strong potentials. The results show that a square-well potential reasonably well approximates the nucleon-nucleon interaction if one calculates the correlations between nucleons generated in a region with an r.m.s. radius larger than 1.5-2 fm. Vice versa, the correlations of nucleons emitted from a smaller generation region are sensitive to the form of the assumed nucleon-nucleon potential. (author)

  4. Strong interactions and quantum chromodynamics at the leading logarithm approximation

    International Nuclear Information System (INIS)

    Mantrach, A.

    1982-11-01

    This thesis is a contribution to the study of Quantum Chromodynamics (QCD) at the leading logarithm approximation (LLA). We have used the interpretation of the LLA in terms of the generalized parton model to propose tests of elementary processes of QCD in large transverse momentum photoproduction reactions. We have used the LLA to sum gluon radiation effects induced in high energy hadronic reactions. We have obtained this way a rise of the nucleon-nucleon total cross section of 15 mb from 60 GeV to 540 GeV. We have exploited the existence of a preconfinement transition in the LLA to study scaling violations in the framework of the dual parton model [fr

  5. Multiplicities and parton dynamics

    International Nuclear Information System (INIS)

    Knuteson, R.O.

    1987-01-01

    The production of strongly interacting particles from the annihilation of electrons and positrons at high energies is studied, with emphasis on the multiplicity, or number, of particles produced. A probabilistic branching model based on the leading log approximation in QCD is formulated to predict the evolution of particle number with the energy of collision. Direct integration of a master equation for the probabilities allows a comparison to the experimentally observed particle distribution. The production of strongly interacting particles from proton-antiproton collisions is also considered. A model for the production of particles from parton-parton collisions is presented and the growth in multiplicity with energy demonstrated

  6. The neural network approach to parton fitting

    International Nuclear Information System (INIS)

    Rojo, Joan; Latorre, Jose I.; Del Debbio, Luigi; Forte, Stefano; Piccione, Andrea

    2005-01-01

    We introduce the neural network approach to global fits of parton distribution functions. First we review previous work on unbiased parametrizations of deep-inelastic structure functions with faithful estimation of their uncertainties, and then we summarize the current status of neural network parton distribution fits

  7. Implementing NLO DGLAP evolution in parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Höche, Stefan; Krauss, Frank; Prestel, Stefan

    2017-10-01

    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.

  8. Chiral symmetry and the nucleon--nucleon interaction

    International Nuclear Information System (INIS)

    Brown, G.E.

    1977-01-01

    The nucleon--nucleon interaction is understood in terms of a dynamic model, the sigma model. The anti NN → ππ helicity amplitudes are assumed to be physical data, and the dynamical model must reproduce these data, more or less. 14 references

  9. Baryon stopping and strangeness baryon production in a parton cascade model

    International Nuclear Information System (INIS)

    Nara, Yasushi

    1999-01-01

    A parton cascade model which is based on pQCD incorporating hard partonic scattering and dynamical hadronization scheme describes the space-time evolution of parton/hadron system produced by ultra-relativistic nuclear collisions. Hadron yield, baryon stopping and transverse momentum distribution are calculated and compared with experimental data at SPS energies. Using new version of parton cascade code VNI in which baryonic cluster formation is implemented, we calculate the net baryon number distributions and Λ yield. It is found that baryon stopping behavior at SPS energies is well accounted for within the parton cascade picture. As a consequence of the production of the baryon (u and d quark) rich parton matter, parton coalescence naturally explains the enhanced yield of Λ particle which has been observed in experiment. (author)

  10. Nucleon-nucleon interaction with quark exchanges and prediction to colour van der Waals potential

    International Nuclear Information System (INIS)

    Osman, A.

    1985-11-01

    The nucleon-nucleon interaction is considered by including the colour nucleon clusters. The nucleon-nucleon system is treated as a six-quark system. The obtained local potentials reduce the short-range repulsion. The resulted nucleon-nucleon potential by using a quark-quark potential well agrees with the central-force potentials. The phase shifts calculated by using these local potentials are in good agreement with those obtained from other methods. Introducing the quark-quark potential in the nucleon-nucleon interaction, leads to a colour van der Waals potential very strong compared with that predicted by experiments. (author)

  11. Medium Modifications of Hadron Properties and Partonic Processes

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, W. K.; Strauch, S.; Tsushima, K.

    2011-06-01

    Chiral symmetry is one of the most fundamental symmetries in QCD. It is closely connected to hadron properties in the nuclear medium via the reduction of the quark condensate , manifesting the partial restoration of chiral symmetry. To better understand this important issue, a number of Jefferson Lab experiments over the past decade have focused on understanding properties of mesons and nucleons in the nuclear medium, often benefiting from the high polarization and luminosity of the CEBAF accelerator. In particular, a novel, accurate, polarization transfer measurement technique revealed for the first time a strong indication that the bound proton electromagnetic form factors in 4He may be modified compared to those in the vacuum. Second, the photoproduction of vector mesons on various nuclei has been measured via their decay to e+e- to study possible in-medium effects on the properties of the rho meson. In this experiment, no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson has been observed, providing tight constraints on model calculations. Finally, processes involving in-medium parton propagation have been studied. The medium modifications of the quark fragmentation functions have been extracted with much higher statistical accuracy than previously possible.

  12. Probe initial parton density and formation time via jet quenching

    International Nuclear Information System (INIS)

    Wang, Xin-Nian

    2002-01-01

    Medium modification of jet fragmentation function due to multiple scattering and induced gluon radiation leads directly to jet quenching or suppression of leading particle distribution from jet fragmentation. One can extract an effective total parton energy loss which can be related to the total transverse momentum broadening. For an expanding medium, both are shown to be sensitive to the initial parton density and formation time. Therefore, one can extract the initial parton density and formation time from simultaneous measurements of parton energy loss and transverse momentum broadening. Implication of the recent experimental data on effects of detailed balance in parton energy loss is also discussed

  13. Flavor asymmetry of the nucleon sea and the five-quark components of the nucleons.

    Science.gov (United States)

    Chang, Wen-Chen; Peng, Jen-Chieh

    2011-06-24

    The existence of the five-quark Fock states for the intrinsic charm quark in the nucleons was suggested some time ago, but conclusive evidence is still lacking. We generalize the previous theoretical approach to the light-quark sector and study possible experimental signatures for such five-quark states. In particular, we compare the d-ū and ū + d-s-s data with the calculations based on the five-quark Fock states. The qualitative agreement between the data and the calculations is interpreted as evidence for the existence of the intrinsic light-quark sea in the nucleons. The probabilities for the |uuduū and |uuddd Fock states are also extracted.

  14. Design of a polarized target made of pure HD: analysis and distillation of HD, resonant virtual Compton scattering on the nucleon at TJNAF; Developpement d'une cible polarisee de pur HD: analyse et distillation du HD, diffusion compton virtuelle resonante sur le nucleon a TJNAF

    Energy Technology Data Exchange (ETDEWEB)

    Bouchigny, S

    2004-04-01

    The first part describe my work on the frozen spin target project HYDILE. This target has to be made of very pure HD (Hydrogen Deuterium), better than 99.95%. However, commercial HD is never found with a concentration better than 98%. The goal was, then, to build an HD distillation facility which could produce pure HD. We describe, in this thesis, the design of the distillator and the implementation of a quadrupole mass spectrometer to monitor the HD purity during the distillation process. The second part of the thesis concerns the analysis taken at the electron accelerator facility TJNAF (Virginia, USA). We look at the electroproduction of Delta resonances involving Deep Virtual Compton Scattering (DeltaVCS). The interpretation of this reaction in terms of GPDs (Generalized Parton Distribution) can provide new insights to the nucleon structure. We focus on the measurement of the beam spin asymmetry which comes from the interference of the Bethe Heitler process with the DeltaVCS. (author)

  15. to view fulltext PDF

    Indian Academy of Sciences (India)

    V S Uma, Alpana Goel, ... Keynote address: High energy physics in 2014 and its future . ... A two-component dark matter model with real singlet scalars confronting GeV ... Nucleon-generalized parton distributions in the light-front quark model .

  16. Nucleon-nucleon interaction with quark exchange and prediction of the color van der Waals potential

    International Nuclear Information System (INIS)

    Osman, A.

    1988-01-01

    The nucleon-nucleon interaction is considered by including the color nucleon clusters. The nucleon-nucleon system is treated as a six-quark system. The obtained local potentials reduce the short-range repulsion. The resulting nucleon-nucleon potential, using a quark-quark potential, agress well with the central-force potentials. The phase shifts calculated by using these local potentials are in good agreement with those obtained from other methods. Introducing the quark-quark potential in the nucleon-nucleon interaction leads to a color van der Waals potential much stronger than that implied by experiments

  17. Model of homogeneous nucleus. Total and inelastic cross sections of nucleon-nucleus scattering

    International Nuclear Information System (INIS)

    Ponomarev, L.A.; Smorodinskaya, N.Ya.

    1985-01-01

    It is shown that the nucleon-nuckleus scattering amplitude at high energy can be easily calculated by generalization of the nucleon-nucleon scattering amplitude and satisfies a simple factorization relation. As distinct from the Glauber model, the suggested approach makes no use of the nucleonic structure of the nucleus and the hadron-nucleus scattering amplitude is not expressed in terms of hadron-nucleon scattering amplitudes. The energy dependence of total and inelastic cross sections is successfully described for a number of nuclei

  18. Pion transverse momentum dependent parton distributions in the Nambu and Jona-Lasinio model

    Energy Technology Data Exchange (ETDEWEB)

    Noguera, Santiago [Departament de Fisica Teòrica and IFIC, Universitat de València - CSIC,E-46100 Burjassot (Spain); Scopetta, Sergio [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia,via A. Pascoli, I - 06123 Perugia (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, via A. Pascoli, I - 06123 Perugia (Italy)

    2015-11-16

    An explicit evaluation of the two pion transverse momentum dependent parton distributions at leading twist is presented, in the framework of the Nambu-Jona Lasinio model with Pauli-Villars regularization. The transverse momentum dependence of the obtained distributions is generated solely by the dynamics of the model. Using these results, the so called generalized Boer-Mulders shift is studied and compared with recent lattice data. The obtained agreement is very encouraging, in particular because no additional parameter has been introduced. A more conclusive comparison would require a precise knowledge of the QCD evolution of the transverse momentum dependent parton distributions under scrutiny.

  19. Spin correlations in the Drell–Yan process, parton entanglement, and other unconventional QCD effects

    Energy Technology Data Exchange (ETDEWEB)

    Nachtmann, O., E-mail: O.Nachtmann@thphys.uni-heidelberg.de

    2014-11-15

    We review ideas on the structure of the QCD vacuum which had served as motivation for the discussion of various non-standard QCD effects in high-energy reactions in articles from 1984 to 1995. These effects include, in particular, transverse-momentum and spin correlations in the Drell–Yan process and soft photon production in hadron–hadron collisions. We discuss the relation of the approach introduced in the above-mentioned articles to the approach, developed later, using transverse-momentum-dependent parton distributions (TDMs). The latter approach is a special case of our more general one which allows for parton entanglement in high-energy reactions. We discuss signatures of parton entanglement in the Drell–Yan reaction. Also for Higgs-boson production in pp collisions via gluon–gluon annihilation effects of entanglement of the two gluons are discussed and are found to be potentially important. These effects can be looked for in the current LHC experiments. In our opinion studying parton-entanglement effects in high-energy reactions is, on the one hand, very worthwhile by itself and, on the other hand, it allows to perform quantitative tests of standard factorisation assumptions. Clearly, the experimental observation of parton-entanglement effects in the Drell–Yan reaction and/or in Higgs-boson production would have a great impact on our understanding how QCD works in high-energy collisions.

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

    International Nuclear Information System (INIS)

    Barik, N.; Mishra, R.N.

    2001-01-01

    Considering the nucleon as consisting entirely of its valence quarks confined independently in a scalar-vector harmonic potential; unpolarized structure functions F 1 (x, μ 2 ) and F 2 (x, μ 2 ) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions u v (x, μ 2 ) and d v (x, μ 2 ) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of μ 2 = 0.07 GeV 2 to a higher Q 2 scale of Q 0 2 = 15 GeV 2 yields xu v (x, Q 0 2 ) and xd v (x, Q 0 2 ) in good agreement with experimental data. The gluon and sea-quark distributions such as G (x, Q 0 2 ) and q s (x, Q 0 2 ) 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. (author)

  1. Nucleon-nucleon scattering phase shifts

    International Nuclear Information System (INIS)

    Bryan, R.

    1978-01-01

    Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the 1 D 2 and 3 F 3 states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references

  2. On the nucleon renormalization in many nucleon problems due to pionic degrees of freedom

    International Nuclear Information System (INIS)

    Sauer, P.U.; Sawicki, M.; Furui, Sadataka.

    1985-01-01

    Conceptual problems of unified two-nucleon force models are discussed. The force models are based on the pion-nucleon vertex and attempt a description of the nucleon-nucleon interaction below and above pion threshold. The conceptual problems arise from the nucleon renormalization due to pionic degrees of freedom. Keeping channels with a single pion only no renormalization procedure can be given which is consistent in the one-nucleon and in the many-nucleon systems. The medium dependence of the one-pion exchange potential is illustrated. (author)

  3. The nucleon-nucleon interaction in the framework of the boson exchange model

    International Nuclear Information System (INIS)

    Niephaus, G.H.

    1984-01-01

    The aim of this thesis was the description of the nucleon-nucleon interaction in a microscopically founded model. For this the description of the 2-nucleon problem by an interacting 2-nucleon-pion system was presented. The starting point of our description was a relativistic eigenvalue equation for the system of mesons and two baryons. The interaction of the baryons with the mesons was described by interaction Hamiltonians. By the elimination of antinucleon states by means of a unitary tansformation (Foldy-Wouthuysen transformation) the interaction Hamiltonians for nucleons could be generated for the field-theoretical Lagrangian densities. The Hamiltonians for resonant baryon states were obtained by means of a simplified procedure from the corresponding Lagrangian densities. Because the determination of Lagrangian densities is not unique, for the pion-nucleon coupling two alternative Lagrangian densities were allowed. For the interaction of positive-energy nucleonic states these two coupling yield nearly equal results; the production or annihilation of negative-energy nucleon states (antiparticles) the predictions however are very different. (orig./HSI) [de

  4. Proton and neutron polarized targets for nucleon-nucleon experiments at SATURNE II

    International Nuclear Information System (INIS)

    Ball, J.; Combet, M.; Sans, J.L.; Benda, B.; Chaumette, P.; Deregel, J.; Durand, G.; Dzyubak, A.P.; Gaudron, C.; Lehar, F.; Janout, Z.; Khachaturov, B.A.

    1996-01-01

    A SATURNE polarized target has been used for nucleon-nucleon elastic scattering and transmission experiments for 15 years. The polarized proton target is a 70 cm 3 cartridge loaded with Pentanol-2. For polarized neutron target, two cartridges loaded with 6 LiD and 6 LiH are set in the refrigerator and can be quickly inserted in the beam. First experiments using 6 Li products in quasielastic pp or pn analyzing power measurements are compared with the same observables measured in a free nucleon-nucleon scattering using polarized proton targets. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon-nucleon scattering is shown for different targets. (author)

  5. Double Polarized Neutron-Proton Scattering and Meson-Exchange Nucleon-Nucleon Potential Models

    International Nuclear Information System (INIS)

    Raichle, B.W.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Walston, J.R.; Tornow, W.; Wilburn, W.S.; Raichle, B.W.; Gould, C.R.; Haase, D.G.; Seely, M.L.; Walston, J.R.; Tornow, W.; Wilburn, W.S.; Penttilae, S.I.; Hoffmann, G.W.

    1999-01-01

    We report on polarized beam - polarized target measurements of the spin-dependent neutron-proton total cross-section differences in longitudinal and transverse geometries (Δσ L and Δσ T , respectively) between E n =5 and 20MeV. Single-parameter phase-shift analyses were performed to extract the phase-shift mixing parameter var-epsilon 1 , which characterizes the strength of the nucleon-nucleon tensor interaction at low energies. Consistent with the trend of previous determinations at E n =25 and 50MeV, our values for var-epsilon 1 imply a stronger tensor force than predicted by meson-exchange nucleon-nucleon potential models and nucleon-nucleon phase-shift analyses. copyright 1999 The American Physical Society

  6. Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei

    International Nuclear Information System (INIS)

    Leitch, M.J.

    1989-01-01

    Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs

  7. Parton dynamics in hadronic processes. Final report

    International Nuclear Information System (INIS)

    Sukhatme, U.P.

    1984-07-01

    We have elucidated several aspects of the dual parton fragmentation model for low transverse momentum multiparticle production in hadronic collisions previously developed by the author and collaborators at Orsay, France. In particular, we have verified that the dual parton model correctly reproduces recently obtained two particle inclusive distributions and particle ratios in the central region of pp and anti pp collisions. This work sheds light on the dynamics of partons in a hadronic collision since it strongly indicates that a valence quark from each initial hadron is held back with a small momentum fraction. Also, we have extended the dual parton approach to include diffraction dissocation and studied the consequences on inclusive pion production in pp interactions. We have investigated the virtues and limitations of logarithmic perturbation theory, which is often a much simpler alternative to standard Rayleigh-Schroedinger perturbation theory. Finally, we have developed and studied the shifted 1/N expansion for the enrgy eigenstates in non-relativistic quantum mechanics. Our results provide an accurate, rapidly convergent, powerful new way of handling any spherically symmetric potential. 18 references

  8. A Parton Shower for High Energy Jets

    CERN Document Server

    Andersen, Jeppe R; Smillie, Jennifer M

    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 it is important that the corresponding divergences in the parton shower are subtracted, keeping only the collinear parts. We present a novel, shower-independent method for achieving this, enabling us to generate fully exclusive and hadronized events with multiple hard jets, in hadronic collisions. We discuss in detail the arising description of the soft, collinear and hard regions by examples in pure QCD jet-production.

  9. Solitary wave exchange potential and nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Prema, K.; Raghavan, S.S.; Sekhar Raghavan

    1986-11-01

    Nucleon-nucleon interaction is studied using a phenomenological potential model called solitary wave exchange potential model. It is shown that this simple model reproduces the singlet and triplet scattering data and the deuteron parameters reasonably well. (author). 6 refs, 2 figs, 1 tab

  10. Nucleon-nucleon scattering in the functional quantum theory of the non-linear spinor field

    International Nuclear Information System (INIS)

    Philipp, W.

    1975-01-01

    The nucleon-nucleon and nucleon-antinucleon scattering cross sections are calculated in the frame of the functional quantum field theory by means of two different approximation methods: averaging by integration of indefinite integrals and pulse averaging. The results for nucleon-nucleon scattering are compared with experimental data, with calculations using a modified functional scalar product and with results in first order perturbation theory (V-A-coupling). As for elastic nucleon-antinucleon scattering, the S matrix is investigated for crossing symmetry. Scattering of 'nucleons' of different mass results in different cross sections even in the lowest-order approximation. (BJ) [de

  11. Parton showers with quantum interference

    CERN Document Server

    Nagy, Zoltan

    2007-01-01

    We specify recursive equations that could be used to generate a lowest order parton shower for hard scattering in hadron-hadron collisions. The formalism is based on the factorization soft and collinear interactions from relatively harder interactions in QCD amplitudes. It incorporates quantum interference between different amplitudes in those cases in which the interference diagrams have leading soft or collinear singularities. It incorporates the color and spin information carried by partons emerging from a hard interaction. One motivation for this work is to have a method that can naturally cooperate with next-to-leading order calculations.

  12. Parton showers with quantum interference

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2007-01-01

    We specify recursive equations that could be used to generate a lowest order parton shower for hard scattering in hadron-hadron collisions. The formalism is based on the factorization soft and collinear interactions from relatively harder interactions in QCD amplitudes. It incorporates quantum interference between different amplitudes in those cases in which the interference diagrams have leading soft or collinear singularities. It incorporates the color and spin information carried by partons emerging from a hard interaction. One motivation for this work is to have a method that can naturally cooperate with next-to-leading order calculations

  13. Theoretical aspects of the nucleon-nucleon workshop

    International Nuclear Information System (INIS)

    Silbar, R.R.

    1984-01-01

    This report concentrates on the inelastic NN system from 300 to 1500 MeV. Topics covered include the visibility of quark signals, dibaryons, the model dependence of predicted NN inelasticities, and a review of how well present conventional models compare with a rapidly expanding database. The general conclusion is that there is so far no clear evidence in the NN system at intermediate energies for unconventional dibaryon resonances. Short remarks are also made concerning one theoretical contribution on elastic scattering and on new experimental results for deuteron photo-disintegration and pion-nucleon charge exchange. 11 references

  14. Fully NLO Parton Shower in QCD

    International Nuclear Information System (INIS)

    Skrzypek, M.; Jadach, S.; Slawinska, M.; Gituliar, O.; Kusina, A.; Placzek, W.

    2011-01-01

    The project of constructing a complete NLO-level Parton Shower Monte Carlo for the QCD processes developed in IFJ PAN in Krakow is reviewed. Four issues are discussed: (1) the extension of the standard inclusive collinear factorization into a new, fully exclusive scheme; (2) reconstruction of the LO Parton Shower in the new scheme; (3) inclusion of the exclusive NLO corrections into the hard process and (4) inclusion of the exclusive NLO corrections into the evolution (ladder) part. (authors)

  15. Triple collinear emissions in parton showers

    Energy Technology Data Exchange (ETDEWEB)

    Höche, Stefan; Prestel, Stefan

    2017-10-01

    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.

  16. Improved quasi parton distribution through Wilson line renormalization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiunn-Wei [Department of Physics, Center for Theoretical Sciences, and Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei, 106, Taiwan (China); Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ji, Xiangdong [INPAC, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240 (China); Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, MD 20742 (United States); Zhang, Jian-Hui, E-mail: jianhui.zhang@physik.uni-regensburg.de [Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg (Germany)

    2017-02-15

    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.

  17. 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.

  18. Investigation of the nucleon-nucleon tensor force in three-nucleon system

    Energy Technology Data Exchange (ETDEWEB)

    Clajus, M.; Egun, P.M.; Gruebler, W.; Hautle, P. (Eidgenoessische Technische Hochschule, Zurich (Switzerland). Inst. fuer Mittelenergiephysik); Slaus, I. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Vuaridel, B. (Michigan Univ., Ann Arbor (USA) Brookhaven National Lab., Upton, NY (USA)); Sperisen, F. (Indiana Univ., Bloomington (USA). Cyclotron Facility); Kretschmer, W.; Rauscher, A.; Schuster, W.; Weidmann, R.; Haller, M. (Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.)); Bruno, M.; Cannata, F.; D' Agostino, M. (Istituto Nazionale di Fisica Nucleare, Bologna (Italy)); Witala, H.; Cornelius, T.; Gloeckle, W. (Bochum Univ. (Germany, F.R.)); Schmelzbach, P.A. (Paul Scherrer Inst., Villigen (Switzerland))

    1990-08-16

    Proton-deuteron elastic scattering has been investigated at E{sub p}=22.7 MeV by comparison of rigorous Faddeev calculations with experimental results. The observable most sensitive to the tensor force is the nucleon-nucleon polarization transfer coefficient K{sub y}sup(y'). The new angular distribution of K{sub y}sup(y') clearly favours the tensor force of the Bonn A potential, which is weaker than the one of the Paris potential. (orig.).

  19. Toy model for pion production in nucleon-nucleon collisions

    International Nuclear Information System (INIS)

    Hanhart, C.; Miller, G. A.; Myhrer, F.; Sato, T.; Kolck, U. van

    2001-01-01

    We develop a toy model for pion production in nucleon-nucleon collisions that reproduces some of the features of the chiral Lagrangian calculations. We calculate the production amplitude and examine some common approximations

  20. Parity violation in nuclei: studies of the weak nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Mcdonald, A.B.

    1980-03-01

    The Weinberg-Salam Unified Model of weak and electromagnetic interactions has been very successful in explaining parity violation and neutral current effects in neutrino-nucleon, electron-nucleon and neutrino-electron interactions. A wide variety of nuclear physics parity violation experiments are in progress to measure effects of the weak nucleon-nucleon interaction in few nucleon systems and certain heavier nuclei where enhancements are expected. The current status of these experiments will be reviewed, including details of an experiment at Chalk River to search for parity violation in the photodisintegration of deuterium and an extension of our previous measurements of parity mixing in 21 Ne. The interpretation of results in terms of basic models of the weak interaction will be discussed. (Auth)

  1. Triple parton scatterings in high-energy proton-proton collisions arXiv

    CERN Document Server

    d'Enterria, David

    2017-01-01

    A generic expression to compute triple parton scattering cross sections in high-energy proton-proton (pp) collisions is presented as a function of the corresponding single parton cross sections and the transverse parton profile of the proton encoded in an effective parameter σeff,TPS. The value of σeff,TPS is closely related to the similar effective cross section that characterizes double parton scatterings, and amounts to σeff,TPS=12.5±4.5  mb. Estimates for triple charm (cc¯) and bottom (bb¯) production in pp collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order perturbative calculations for single cc¯, bb¯ cross sections. At s≈100  TeV, about 15% of the pp collisions produce three cc¯ pairs from three different parton-parton scatterings.

  2. Hard probes of short-range nucleon-nucleon correlations

    Energy Technology Data Exchange (ETDEWEB)

    J. Arrington, D. W. Higinbotham, G. Rosner, M. Sargsian

    2012-10-01

    The strong interaction of nucleons at short distances leads to a high-momentum component to the nuclear wave function, associated with short-range correlations between nucleons. These short-range, high-momentum structures in nuclei are one of the least well understood aspects of nuclear matter, relating to strength outside of the typical mean-field approaches to calculating the structure of nuclei. While it is difficult to study these short-range components, significant progress has been made over the last decade in determining how to cleanly isolate short-range correlations in nuclei. We have moved from asking if such structures exist, to mapping out their strength in nuclei and studying their microscopic structure. A combination of several different measurements, made possible by high-luminosity and high-energy accelerators, coupled with an improved understanding of the reaction mechanism issues involved in studying these structures, has led to significant progress, and provided significant new information on the nature of these small, highly-excited structures in nuclei. We review the general issues related to short-range correlations, survey recent experiments aimed at probing these short-range structures, and lay out future possibilities to further these studies.

  3. Parton shower evolution with subleading color

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2012-02-01

    Parton shower Monte Carlo event generators in which the shower evolves from hard splittings to soft splittings generally use the leading color approximation, which is the leading term in an expansion in powers of 1/N c 2 , where N c =3 is the number of colors. We introduce a more general approximation, the LC+ approximation, that includes some of the color suppressed contributions. There is a cost: each generated event comes with a weight. There is a benefit: at each splitting the leading soft x collinear singularity and the leading collinear singularity are treated exactly with respect to color. In addition, an LC+ shower can start from a state of the color density matrix in which the bra state color and the ket state color do not match. (orig.)

  4. Parton shower evolution with subleading color

    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

    2012-02-15

    Parton shower Monte Carlo event generators in which the shower evolves from hard splittings to soft splittings generally use the leading color approximation, which is the leading term in an expansion in powers of 1/N{sub c}{sup 2}, where N{sub c}=3 is the number of colors. We introduce a more general approximation, the LC+ approximation, that includes some of the color suppressed contributions. There is a cost: each generated event comes with a weight. There is a benefit: at each splitting the leading soft x collinear singularity and the leading collinear singularity are treated exactly with respect to color. In addition, an LC+ shower can start from a state of the color density matrix in which the bra state color and the ket state color do not match. (orig.)

  5. Color correlations in parton jet decay

    International Nuclear Information System (INIS)

    Levin, E.M.; Ryskin, M.G.

    1983-01-01

    The pre-confinement effect is discussed. Colour correlations are calculated for the decays of parton jets with account for the coherence of the gluon interaction. It is shown that, in contrast to the results of previous works, the colour correlations between two gluons with a high pair mass can be appreciable. In any kinematical interval, however, the energy carried away be the particles correlated in the colour is always much less than the total energy carried away by the partons

  6. Theoretical Issues

    Energy Technology Data Exchange (ETDEWEB)

    Marc Vanderhaeghen

    2007-04-01

    The theoretical issues in the interpretation of the precision measurements of the nucleon-to-Delta transition by means of electromagnetic probes are highlighted. The results of these measurements are confronted with the state-of-the-art calculations based on chiral effective-field theories (EFT), lattice QCD, large-Nc relations, perturbative QCD, and QCD-inspired models. The link of the nucleon-to-Delta form factors to generalized parton distributions (GPDs) is also discussed.

  7. Pionic background for nucleon-nucleon observables

    International Nuclear Information System (INIS)

    Ballot, J.L.; Robilotta, M.R.

    1992-01-01

    A method is presented that allows the unambiguous definition of the one pion exchange contribution to nucleon-nucleon scattering observables and then use it to determine those waves where values of phase shifts and mixing parameters may be understood as sums of pionic and non-pionic dynamical effects. This helps the assessment of the explicative power of the various existing phenomenological potentials and may eventually lead to ways of discriminating their effectiveness. (author) 16 refs.; 19 figs.; 2 tabs

  8. A parton description of the nucleus fragmentation region in heavy-ion collisions

    International Nuclear Information System (INIS)

    Hwa, R.C.; Oregon Univ., Eugene

    1984-01-01

    In nucleus-nucleus collisions, the rapidity distribution of partons in the nucleus fragmentation region is highly asymmetrical. Thermalization that randomizes the momenta of partons far apart in rapidity cannot be expected. A local thermalization model is introduced which relates temperature to the range of parton interaction in rapidity. The parton number density and energy density are then calculated. (orig.)

  9. The nucleon-nucleus scattering at intermediate energies

    International Nuclear Information System (INIS)

    Auger, J.-P.

    1976-01-01

    The Glauber model has the merit to connect directly the nucleon-nucleus elastic differential cross section with the nucleon-nucleon amplitude and nuclear densities. The general agreement between the 1 GeV proton elastic scattering differential cross sections calculated without adjustable parameter and the experimental data (from He 4 to Pb 208 ) is rather satisfactory up to 2. - 2.5 fm -1 momentum transfer. Although the 1 GeV proton elastic scattering experiments constitute at present one of the best method in determining neutron densities, it seems that self-consistent calculations bring the best knowledge of these densities. The model independent analysis performed with electron and proton scattering experiments show that the difference between neutron and proton r.m.s. radius cannot be determined better than 25-30% for Pb 208 [fr

  10. Nucleon-nucleon interaction of a chiral σ-ω model at finite temperature

    International Nuclear Information System (INIS)

    Rukeng Su

    1994-01-01

    By using the imaginery time Green's function method, the nucleon-nucleon interaction of the chiral σ-ω model has been investigated under the one-loop approximation. The effective masses of the pion, σ-meson and ω-meson at finite temperature are given. We have found that the potential well of the nucleon-nucleon interaction becomes shallow as the temperature increases. At a critical temperature T c (70 MEV) the potential well disappears. (author)

  11. Thermalization through parton transport

    International Nuclear Information System (INIS)

    Zhang Bin

    2010-01-01

    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 α 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.

  12. Deeply virtual compton scattering on the nucleon with the Clas Detector of Jefferson Lab: measurement of the polarized and unpolarized cross sections; Etude de la diffusion compton profondement virtuelle sur le nucleon avec le detecteur Clas de Jefferson Lab: mesure des sections efficaces polarisees et non polarisees

    Energy Technology Data Exchange (ETDEWEB)

    Jo, H.S

    2007-03-15

    The Generalized Parton Distributions (GPDs), introduced in the 1990's, provide the most complete description of the structure (in quarks and gluons) of the nucleon. The Deeply Virtual Compton Scattering (DVCS), which corresponds to the 'hard' exclusive electroproduction of photons on the nucleon, is a key process among the reactions allowing access to the GPDs. A DVCS-dedicated experiment was carried out in 2005 with the CLAS detector of Jefferson Lab, using a polarized electron beam of 5.776 GeV and a hydrogen target. For this experiment, we built and used a dedicated electromagnetic calorimeter capable of detecting the final-state photon. The collected data allowed us to study the DVCS in the widest kinematic range ever accessed for this reaction: 1 < Q{sup 2} < 4.6 GeV{sup 2}, 0.1 < x{sub B} < 0.58, 0.09 < -t < 2 GeV{sup 2}. The work performed during this PhD includes simulation work done for the preparation of the experiment, timing calibration of one of the CLAS subsystems, and data analysis. The aim of the data analysis was the extraction of the unpolarized cross sections of the studied reaction and of the difference of the polarized cross sections, this latter observable being linearly proportional to the GPDs. The obtained results were compared to DVCS theoretical calculations based on one of the most up-to-date GPD parametrizations. (author)

  13. On positivity of parton distributions

    International Nuclear Information System (INIS)

    Altarelli, G.; Forte, S.; Ridolfi, G.

    1998-01-01

    We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be derived within perturbative QCD at leading order when all quark and gluon distributions are defined in terms of suitable physical processes. We specify a convenient physical definition for the polarized and unpolarized gluon distributions in terms of Higgs production from gluon fusion. We show that these bounds are modified by subleading corrections, and we determine them up to NLO. We examine the ensuing phenomenological implications, in particular in view of the determination of the polarized gluon distribution. (orig.)

  14. On positivity of parton distributions

    CERN Document Server

    Altarelli, Guido; Ridolfi, G; Altarelli, Guido; Forte, Stefano; Ridolfi, Giovanni

    1998-01-01

    We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be derived within perturbative QCD at leading order when all quark and gluon distributions are defined in terms of suitable physical processes. We specify a convenient physical definition for the polarized and unpolarized gluon distributions in terms of Higgs production from gluon fusion. We show that these bounds are modified by subleading corrections, and we determine them up to NLO. We examine the ensuing phenomenological implications, in particular in view of the determination of the polarized gluon distribution.

  15. Calculation of the nucleon structure function from the nucleon wave function

    Science.gov (United States)

    Hussar, Paul E.

    1993-01-01

    Harmonic oscillator wave functions have played an historically important role in our understanding of the structure of the nucleon, most notably by providing insight into the mass spectra of the low-lying states. High energy scattering experiments are known to give us a picture of the nucleon wave function at high-momentum transfer and in a frame in which the nucleon is traveling fast. A simple model that crosses the twin bridges of momentum scale and Lorentz frame that separate the pictures of the nucleon wave function provided by the deep inelastic scattering data and by the oscillator model is presented.

  16. Positivity bounds on double parton distributions

    International Nuclear Information System (INIS)

    Diehl, Markus; Kasemets, Tomas

    2013-03-01

    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.

  17. The nucleon-nucleon interaction from a realistic pseudoscalar-vector chiral lagrangian

    International Nuclear Information System (INIS)

    Kaiser, N.; Meissner, U.G.; Massachusetts Inst. of Tech., Cambridge

    1990-01-01

    We investigate the static nucleon-nucleon potential in the framework of a non-linear chiral meson theory. The model includes pions as well as the vector mesons ρ and ω. All parameters are fixed in the meson sector and predictions about the nucleon-nucleon interaction follow without adjusting any parameters. We use an S-matrix approach to calculate correlated two-pion exchange between two solitons. The most prominent feature of this two-pion exchange is that it leads very natural to attraction in the scalar-isoscalar channel. We also discuss the effect of πp correlations on the central potential, and present the spectral function related to the correlated two-pion exchange. Furthermore, we study the form factors of the nucleon sources related to the two-pion exchange and find that they are of dipole type with typical cutoff scales Λ D ≅ 700 MeV. We also discuss the destructive interference of π- and ρ-exchange in the isovector tensor potential. Altogether, we present a unified treatment of meson exchange phenomenology based on a serious model of the nucleon. Finally, we point out the limitations of the model and discuss some further applications. (orig.)

  18. Transverse momentum in double parton scattering. Factorisation, evolution and matching

    Energy Technology Data Exchange (ETDEWEB)

    Buffing, Maarten G.A.; Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kasemets, Tomas [Nikhef, Amsterdam (Netherlands). Theory Group; VU Univ. Amsterdam (Netherlands)

    2017-08-15

    We give a description of double parton scattering with measured transverse momenta in the final state, extending the formalism for factorisation and resummation developed by Collins, Soper and Sterman for the production of colourless particles. After a detailed analysis of their colour structure, we derive and solve evolution equations in rapidity and renormalisation scale for the relevant soft factors and double parton distributions. We show how in the perturbative regime, transverse momentum dependent double parton distributions can be expressed in terms of simpler nonperturbative quantities and compute several of the corresponding perturbative kernels at one-loop accuracy. We then show how the coherent sum of single and double parton scattering can be simplified for perturbatively large transverse momenta, and we discuss to which order resummation can be performed with presently available results. As an auxiliary result, we derive a simple form for the square root factor in the Collins construction of transverse momentum dependent parton distributions.

  19. Transverse momentum in double parton scattering. Factorisation, evolution and matching

    International Nuclear Information System (INIS)

    Buffing, Maarten G.A.; Diehl, Markus; Kasemets, Tomas

    2017-08-01

    We give a description of double parton scattering with measured transverse momenta in the final state, extending the formalism for factorisation and resummation developed by Collins, Soper and Sterman for the production of colourless particles. After a detailed analysis of their colour structure, we derive and solve evolution equations in rapidity and renormalisation scale for the relevant soft factors and double parton distributions. We show how in the perturbative regime, transverse momentum dependent double parton distributions can be expressed in terms of simpler nonperturbative quantities and compute several of the corresponding perturbative kernels at one-loop accuracy. We then show how the coherent sum of single and double parton scattering can be simplified for perturbatively large transverse momenta, and we discuss to which order resummation can be performed with presently available results. As an auxiliary result, we derive a simple form for the square root factor in the Collins construction of transverse momentum dependent parton distributions.

  20. The transverse momentum of partons in large psub(T) processes

    International Nuclear Information System (INIS)

    Chase, M.K.

    1977-11-01

    An approximate method is used to investigate the effects of parton transverse momentum in large psub(T) particle production within the framework of hard scattering models. An approximate expression is derived for the mean bias towards the trigger of each of the two participating partons and it is found that event by event one of the partons is biased more than the other, even with a 90 0 trigger. The transverse momentum of partons and their closely related off mass shell behaviour are treated as a perturbation in the equation for the single particle inclusive cross-section, which is then expanded in a Taylor series. The first non-zero correction term is calculated and it is found that to this order, the cross-section is increased by parton transverse momentum effects by typically a factor of 2 for psub(T) = 2 to 3 GeV/c, and that the correction decreases rapidly with increasing psub(T). (author)

  1. 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.)

  2. Description of a nucleon in nuclear matter

    International Nuclear Information System (INIS)

    Bunatian, G.G.

    1992-01-01

    The nonlinear cloudy bag model, CBM, is generalized to describe a nucleon in nuclear matter at various densities ρ and temperatures T. The influence of the nuclear medium on the bag-nucleon in the framework of CBM is due to the modification of the equation describing the CBM pion field π. These changes are accounted for in the CBM by including in the CBM lagrangian the pion polarization operator π(ρ,T). The free pion propagator D is replaced in a nuclear medium by D(ρ,T). The changing of the pion field π and propagator D leads via the CBM equations to the modification of the bag size R and quark momentum p, determined simultaneously from these equations, and then to modifications of other bag-nucleon characteristics: the total energy E, r.m.s. radii, magnetic moment μ, polarizability α and so on, which all are expressed as the expectation values of the corresponding operators in the bag-nucleon state. The quantity π(ρ,T) was studied in the works whose results are used in this investigation. The nucleon size R in the nuclear matter at normal density ρ o and zero temperature decreases by 5% and the quarks momentum p also decreases, however, insignificantly, by 1-2%. On the other hand, the values of the r.m.s. radii increases by 15% for a proton and by 100% for a neutron. The author has also found that the polarizability of a nucleon in nuclear matter is roughly two times as much as in free space

  3. Parton Distributions and the LHC W and Z Production

    CERN Document Server

    Martin, A D; Stirling, William James; Thorne, R S

    2000-01-01

    W and Z bosons will be produced copiously at the LHC proton-proton collider. We study the parton distribution dependence of the total production cross sections and rapidity distributions, paying particular attention to the uncertainties arising from uncertainties in the parton distributions themselves. Variations in the gluon, the strong coupling, the sea quarks and the overall normalisation are shown to lead to small but non-negligible variations in the cross section predictions. Ultimately, therefore, the measurement of these cross sections will provide a powerful cross check on our knowledge of parton distributions and their evolution.

  4. Hadron structure with light dynamical quarks

    International Nuclear Information System (INIS)

    Edwards, R.G.; Richards, D.G.; Fleming, G.T.; Haegler, P.; Negele, J.W.; Orginos, K.; Pochinsky, A.; Renner, D.B.; Schroers, W.

    2005-09-01

    Generalized parton distributions encompass a wealth of information concerning the three-dimensional quark and gluon structure of the nucleon, and thus provide an ideal focus for the study of hadron structure using lattice QCD. The special limits corresponding to form factors and parton distributions are well explored experimentally, providing clear tests of lattice calculations, and the lack of experimental data for more general cases provides opportunities for genuine predictions and for guiding experiment. We present results from hybrid calculations with improved staggered (Asqtad) sea quarks and domain wall valence quarks at pion masses down to 350 MeV. (orig.)

  5. Evolution of parton densities beyond leading order

    International Nuclear Information System (INIS)

    Curci, G.; Petronzio, R.; Furmanski, W.

    1980-01-01

    We develop a technique, based explicitly on the factorization properties of mass singularities, which allows one to calculate the evolution of parton densities beyond leading order. We present the results for the evolution of hadronic structure functions as well as for parton fragmentation functions into hadrons. Within our scheme the predictions for a particular process are obtained by convoluting a universal parton density with a short-distance cross section specific to the process. As an application, we calculate the QCD predictions for the Q 2 dependence of deep inelastic lepton-hadron scattering and of one-particle inclusive e + e - annihilation cross sections. Our results for electroproduction agree with those obtained with the operator product expansion technique. Physical quantitites in scattering are related to the corresponding ones in annihilation by analytic continuation, whereas the Gribov-Lipatov relation is strongly violated. (orig.)

  6. Proceedings of RIKEN BNL Research Center Workshop: Brookhaven Summer Program on Nucleon Spin Physics

    Energy Technology Data Exchange (ETDEWEB)

    Aschenauer, A.; Qiu, Jianwei; Vogelsang, W.; Yuan, F.

    2011-08-02

    Understanding the structure of the nucleon is of fundamental importance in sub-atomic physics. Already the experimental studies on the electro-magnetic form factors in the 1950s showed that the nucleon has a nontrivial internal structure, and the deep inelastic scattering experiments in the 1970s revealed the partonic substructure of the nucleon. Modern research focuses in particular on the spin and the gluonic structure of the nucleon. Experiments using deep inelastic scattering or polarized p-p collisions are carried out in the US at the CEBAF and RHIC facilities, respectively, and there are other experimental facilities around the world. More than twenty years ago, the European Muon Collaboration published their first experimental results on the proton spin structure as revealed in polarized deep inelastic lepton-nucleon scattering, and concluded that quarks contribute very little to the proton's spin. With additional experimental and theoretical investigations and progress in the following years, it is now established that, contrary to naive quark model expectations, quarks and anti-quarks carry only about 30% of the total spin of the proton. Twenty years later, the discovery from the polarized hadron collider at RHIC was equally surprising. For the phase space probed by existing RHIC experiments, gluons do not seem to contribute any to the proton's spin. To find out what carries the remaining part of proton's spin is a key focus in current hadronic physics and also a major driving force for the new generation of spin experiments at RHIC and Jefferson Lab and at a future Electron Ion Collider. It is therefore very important and timely to organize a series of annual spin physics meetings to summarize the status of proton spin physics, to focus the effort, and to layout the future perspectives. This summer program on 'Nucleon Spin Physics' held at Brookhaven National Laboratory (BNL) on July 14-27, 2010 [http://www.bnl.gov/spnsp/] is the

  7. Induced Hyperon-Nucleon-Nucleon Interactions and the Hyperon Puzzle.

    Science.gov (United States)

    Wirth, Roland; Roth, Robert

    2016-10-28

    We present the first ab initio calculations for p-shell hypernuclei including hyperon-nucleon-nucleon (YNN) contributions induced by a similarity renormalization group transformation of the initial hyperon-nucleon interaction. The transformation including the YNN terms conserves the spectrum of the Hamiltonian while drastically improving model-space convergence of the importance-truncated no-core model, allowing a precise extraction of binding and excitation energies. Results using a hyperon-nucleon interaction at leading order in chiral effective field theory for lower- to mid-p-shell hypernuclei show a good reproduction of experimental excitation energies while hyperon separation energies are typically overestimated. The induced YNN contributions are strongly repulsive and we show that they are related to a decoupling of the Σ hyperons from the hypernuclear system, i.e., a suppression of the Λ-Σ conversion terms in the Hamiltonian. This is linked to the so-called hyperon puzzle in neutron-star physics and provides a basic mechanism for the explanation of strong ΛNN three-baryon forces.

  8. Is nucleon deformed?

    International Nuclear Information System (INIS)

    Abbas, Afsar

    1992-01-01

    The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter P D ∼1/4 (which specifies deformation) fits g A (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(πNΔ), the double delta coupling constant 1 fsub(πΔΔ), the Ml transition moment μΔN and g 1 p the spin structure function of proton 2 . All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs

  9. Parton recombination model

    International Nuclear Information System (INIS)

    Hwa, R.C.

    1978-08-01

    Low P/sub T/ meson production in hadronic collisions is described in the framework of the parton model. The recombination of quark and antiquark is suggested as the dominant mechanism in the large x region. Phenomenological evidences for the mechanism are given. The application to meson initiated reactions yields the quark distribution in mesons. 21 references

  10. One-boson-exchange approach to dilepton production in nucleon-nucleon collisions

    International Nuclear Information System (INIS)

    Haglin, K.L.

    1991-01-01

    The author calculates energy-dependent nucleon-nucleon elastic cross sections and electron-positron pair production differential cross sections for the processes pp → pp, np → np, and pp → ppe + e - , np → npe + e - at laboratory kinetic energies in the 1-5 GeV range. These calculations will be based on a one-boson-exchange (π, ρ, ω, σ, δ, η) approximation to the nucleon-nucleon scattering problem. Strong form factors are included in a manner which preserves gauge invariance. He finds excellent results as compared with data for the total elastic cross sections. The calculate differential elastic cross sections show only qualitative agreement with data. For dilepton production in n-p scattering the model overestimates the number of pairs as compared with proton on beryllium data. For the p-p case he finds the tensor coupling of the ρ to the nucleons to be clearly dominant. Data do not yet exist for the p-p case at these energies: the author predicts them

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

    Energy Technology Data Exchange (ETDEWEB)

    Barik, N [Dept. of Physics, Utkal Univ., Bhubaneswar (India); Mishra, R N [Dept. of Physics, Dhenkanal College, Dhenkanal (India)

    2001-04-01

    Considering the nucleon as consisting entirely of its valence quarks confined independently in a scalar-vector harmonic potential; unpolarized structure functions F{sub 1} (x, {mu}{sup 2}) and F{sub 2} (x, {mu}{sup 2}) are derived in the Bjorken limit under certain simplifying assumptions; from which valence quark distribution functions u{sub v} (x, {mu}{sup 2}) and d{sub v} (x, {mu}{sup 2}) are appropriately extracted satisfying the normalization constraints. QCD-evolution of these input distributions from a model scale of {mu}{sup 2} = 0.07 GeV{sup 2} to a higher Q{sup 2} scale of Q{sub 0}{sup 2} = 15 GeV{sup 2} yields xu{sub v} (x, Q{sub 0}{sup 2}) and xd{sub v} (x, Q{sub 0}{sup 2}) in good agreement with experimental data. The gluon and sea-quark distributions such as G (x, Q{sub 0}{sup 2}) and q{sub s} (x, Q{sub 0}{sup 2}) 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. (author)

  12. Large psub(T) pion production and clustered parton model

    Energy Technology Data Exchange (ETDEWEB)

    Kanki, T [Osaka Univ., Toyonaka (Japan). Coll. of General Education

    1977-05-01

    Recent experimental results on the large p sub(T) inclusive ..pi../sup 0/ productions by pp and ..pi..p collisions are interpreted by the parton model in which the constituent quarks are defined to be the clusters of the quark-partons and gluons.

  13. Nucleon-nucleon theory and phenomenology. Progress report and renewal proposal, June 1, 1981-May 31, 1982

    International Nuclear Information System (INIS)

    Signell, P.

    1981-01-01

    This project has involved five inter-related subprojects: (1) derivation of the intermediate range nucleon-nucleon interaction using a new method that utilizes much shorter and simpler analytic continuation through the unphysical region that lies between the πN and ππ physical regions of the N anti N → ππ amplitude (with signifantly improved accuracy for the nucleon-nucleon interaction); (2) construction of a short range phenomenological potential that, with the theoretical part mentioned above, gives a precise fit to the nucleon-nucleon data and is parameterized for easy use in nucleon calculations; (3) phase shift analyses of the world data below 400 MeV, especially the large amount of very precise data below 20 meV and the new data near 55 MeV that have never been analyzed properly; (4) the introduction of a K-matrix formulation of the Optimal Polynomial Expansion in order to accelerate convergence of the partial wave series at LAMPF energies; and (5) setting up of a cooperatively evaluated permanent nucleon-nucleon data bank in the 1-1200 MeV range that can be used by all nucleon-nucleon researchers

  14. 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. [Nikhef Theory Group, Amsterdam (Netherlands); Amsterdam VU Univ. (Netherlands)

    2016-11-15

    An important question in the theory of double parton scattering is how to incorporate the possibility of the parton pairs being generated perturbatively via 1→ 2splitting into the theory, whilst avoiding double counting with single parton scattering loop corrections. Here, we describe a consistent approach for solving this problem, which retains the notion of double parton distributions (DPDs) for individual hadrons. Further, we discuss the construction of appropriate model DPDs in our framework, and the use of these to compute the DPS part, presenting DPS 'luminosities' from our model DPDs for a few sample cases.

  15. Studies of the nucleon-nucleus and the nucleon-nucleon interactions using polarized neutron beams

    International Nuclear Information System (INIS)

    Walter, R.L.; Howell, C.R.; Tornow, W.

    1988-01-01

    The results o four scattering measurements using beams of polarized neutrons are described. Results for the analyzing power A y (θ) for elastic scattering of neutrons from protons and deuterons are compared to calculations based on the Paris and the Bonn nucleon-nucleon interactions. Deficiencies particularly in the Bonn model are indicated. A nucleon-nucleus potential is derived from σ(θ) and A y (θ) data for n + 28 Si and p + 28 Si and the Coulomb correction terms are derived according to two approaches. A Fourier-Bessel expansion is used to investigate the form factors of the terms of the n + 208 Pb potential which are necessary to describe σ(θ) and A y (θ) data from 6 to 10 MeV. The nature of the spin-orbit term is also presented. (author)

  16. Parton model (Moessbauer) sum rules for b → c decays

    International Nuclear Information System (INIS)

    Lipkin, H.J.

    1993-01-01

    The parton model is a starting point or zero-order approximation in many treatments. The author follows an approach previously used for the Moessbauer effect and shows how parton model sum rules derived for certain moments of the lepton energy spectrum in b → c semileptonic decays remain valid even when binding effects are included. The parton model appears as a open-quote semiclassical close-quote model whose results for certain averages also hold (correspondence principle) in quantum mechanics. Algebraic techniques developed for the Moessbauer effect exploit simple features of the commutator between the weak current operator and the bound state Hamiltonian to find the appropriate sum rules and show the validity of the parton model in the classical limit, ℎ → 0, where all commutators vanish

  17. Parton shower and NLO-matching uncertainties in Higgs boson pair production

    Science.gov (United States)

    Jones, Stephen; Kuttimalai, Silvan

    2018-02-01

    We perform a detailed study of NLO parton shower matching uncertainties in Higgs boson pair production through gluon fusion at the LHC based on a generic and process independent implementation of NLO subtraction and parton shower matching schemes for loop-induced processes in the Sherpa event generator. We take into account the full top-quark mass dependence in the two-loop virtual corrections and compare the results to an effective theory approximation. In the full calculation, our findings suggest large parton shower matching uncertainties that are absent in the effective theory approximation. We observe large uncertainties even in regions of phase space where fixed-order calculations are theoretically well motivated and parton shower effects expected to be small. We compare our results to NLO matched parton shower simulations and analytic resummation results that are available in the literature.

  18. Regularization and the potential of effective field theory in nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Phillips, D.R.

    1998-04-01

    This paper examines the role that regularization plays in the definition of the potential used in effective field theory (EFT) treatments of the nucleon-nucleon interaction. The author considers N N scattering in S-wave channels at momenta well below the pion mass. In these channels (quasi-)bound states are present at energies well below the scale m π 2 /M expected from naturalness arguments. He asks whether, in the presence of such a shallow bound state, there is a regularization scheme which leads to an EFT potential that is both useful and systematic. In general, if a low-lying bound state is present then cutoff regularization leads to an EFT potential which is useful but not systematic, and dimensional regularization with minimal subtraction leads to one which is systematic but not useful. The recently-proposed technique of dimensional regularization with power-law divergence subtraction allows the definition of an EFT potential which is both useful and systematic

  19. Parton-shower uncertainties with Herwig 7: benchmarks at leading order

    Energy Technology Data Exchange (ETDEWEB)

    Bellm, Johannes; Schichtel, Peter [Durham University, Department of Physics, IPPP, Durham (United Kingdom); Nail, Graeme [University of Manchester, Particle Physics Group, School of Physics and Astronomy, Manchester (United Kingdom); Karlsruhe Institute of Technology, Institute for Theoretical Physics, Karlsruhe (Germany); Plaetzer, Simon [Durham University, Department of Physics, IPPP, Durham (United Kingdom); University of Manchester, Particle Physics Group, School of Physics and Astronomy, Manchester (United Kingdom); Siodmok, Andrzej [CERN, TH Department, Geneva (Switzerland); Polish Academy of Sciences, The Henryk Niewodniczanski Institute of Nuclear Physics in Cracow, Krakow (Poland)

    2016-12-15

    We perform a detailed study of the sources of perturbative uncertainty in parton-shower predictions within the Herwig 7 event generator. We benchmark two rather different parton-shower algorithms, based on angular-ordered and dipole-type evolution, against each other. We deliberately choose leading order plus parton shower as the benchmark setting to identify a controllable set of uncertainties. This will enable us to reliably assess improvements by higher-order contributions in a follow-up work. (orig.)

  20. Parton Shower Uncertainties with Herwig 7: Benchmarks at Leading Order

    CERN Document Server

    Bellm, Johannes; Plätzer, Simon; Schichtel, Peter; Siódmok, Andrzej

    2016-01-01

    We perform a detailed study of the sources of perturbative uncertainty in parton shower predictions within the Herwig 7 event generator. We benchmark two rather different parton shower algorithms, based on angular-ordered and dipole-type evolution, against each other. We deliberately choose leading order plus parton shower as the benchmark setting to identify a controllable set of uncertainties. This will enable us to reliably assess improvements by higher-order contributions in a follow-up work.

  1. The nucleon as a projected chiral soliton: vacuum and medium properties

    International Nuclear Information System (INIS)

    Fiolhais, M.; Alberto, P.; Ruiz Arriola, E.; Christov, C.V.; Bylgarska Akademiya na Naukite, Sofia

    1990-01-01

    Nucleon properties and nucleon form factors are computed within the framework of the projected linear chiral soliton model. To this end the Gell-Mann - Levy lagrangian is solved by means of variational methods which include angular momentum and isospin projection with trial quark-boson Fock states in generalized hedgehog configurations. The consistency of the treatment is checked by the fulfillment of virial theorems such as Goldberger-Treiman relation. In general the q 2 dependence of the nucleon form factors are well described although some of their values at zero momentum transfer come out too large, namely for the axial- and πN N- form factors. Electromagnetic form factors for the N - Δ transition are also calculated and compared with the available experimental data. Medium effects on the nucleon properties are investigated combining the projected chiral soliton model with the Nambu-Jona-Lasinio model. The latter is employed to compute the pion decay constant and the pion and sigma masses at finite medium density. These meson properties fix the parameters in the linear sigma model, which is then solved using the same variational methods as for the zero density. The nucleon mass shows a decrease of 17% and the proton radius an increase of 19% if the medium reaches nuclear matter density. The magnetic moments and g A are less affected by the medium. The nucleon electromagnetic form factors show remarkable changes at finite transfer numbers as well. (author)

  2. Improved modelling of independent parton hadronization

    International Nuclear Information System (INIS)

    Biddulph, P.; Thompson, G.

    1989-01-01

    A modification is proposed to current versions of the Field-Feynman ansatz for the hadronization of a quark in Monte Carlo models of QCD interactions. This faster-running algorithm has no more parameters and imposes a better degree of energy conservation. It results in naturally introducing a limitation of the transverse momentum distribution, similar to the experimentally observed ''seagull'' effect. There is now a much improved conservation of quantum numbers between the original parton and resultant hadrons, and the momentum of the emitted parton is better preserved in the summed momentum vectors of the final state particles. (orig.)

  3. Partons and the EMC spin effect

    International Nuclear Information System (INIS)

    Bass, S.D.

    1992-03-01

    We focus on the patron model and the role of the axial anomaly in polarised deep inelastic scattering. We show that the axial anomaly is relevant to each of the higher moments of the spin dependent structure function g 1 (x) and not just the first moment. This result implies that the factorisation of mass singularities is not sufficient to define the parton model in spin dependent quantum chromodynamics (QCD). (It is certainly a necessary condition.) We also need to consider the locality of the photon parton interaction. The anomaly is observed over all x in the (EMC)g 1 (x) data. (author)

  4. Excitation of Nucleon Resonances

    International Nuclear Information System (INIS)

    Burkert, Volker D.

    2001-01-01

    I discuss developments in the area of nucleon resonance excitation, both necessary and feasible, that would put our understanding of nucleon structure in the regime of strong QCD on a qualitatively new level. They involve the collection of high quality data in various channels, a more rigorous approach in the search for ''missing'' resonances, an effort to compute some critical quantities in nucleon resonance excitations from first principles, i.e. QCD, and a proposal focused to obtain an understanding of a fundamental quantity in nucleon structure

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

    International Nuclear Information System (INIS)

    Venugopalan, R.

    1995-01-01

    We construct a weak coupling, many body theory to compute parton distributions in large nuclei for x much-lt A - 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

  6. Wee partons in large nuclei: from virtual dream to hard reality

    International Nuclear Information System (INIS)

    Venugopalan, R.

    1995-01-01

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

  7. Taylor-series method for four-nucleon wave functions

    International Nuclear Information System (INIS)

    Sandulescu, A.; Tarnoveanu, I.; Rizea, M.

    1977-09-01

    Taylor-series method for transforming the infinite or finite well two-nucleon wave functions from individual coordinates to relative and c.m. coordinates, by expanding the single particle shell model wave functions around c.m. of the system, is generalized to four-nucleon wave functions. Also the connections with the Talmi-Moshinsky method for two and four harmonic oscillator wave functions are deduced. For both methods Fortran IV programs for the expansion coefficients have been written and the equivalence of corresponding expressions numerically proved. (author)

  8. Scattering of vector mesons off nucleons

    International Nuclear Information System (INIS)

    Lutz, M.F.M.; Friman, B.; Wolf, G.

    2001-12-01

    We construct a relativistic and unitary approach to 'high' energy pion- and photon-nucleon reactions taking the πN, πΔ, ρN, ωN, ηN, K Λ, KΣ final states into account. Our scheme dynamically generates the s- and d-wave nucleon resonances N(1535), N(1650) and N(1520) and isobar resonances Δ(1620) and δ(1700) in terms of quasi-local interaction vertices. The description of photon-induced processes is based on a generalized vector-meson dominance assumption which directly relates the electromagnetic quasi-local 4-point interaction vertices to the corresponding vertices involving the ρ and ω fields. We obtain a satisfactory description of the elastic and inelastic pion- and photon-nucleon scattering data in the channels considered. The resulting s-wave ρ- and ω-nucleon scattering amplitudes are presented. Using these amplitudes we compute the leading density modification of the ρ and ω mass distributions in nuclear matter. We find a repulsive mass shift for the ω meson at small nuclear density but predict considerable strength in resonance-hole like ω-meson modes. Compared to previous calculations our result for the ρ-meson spectral function shows a significantly smaller in-medium effect. This reflects a not too large coupling strength of the N(1520) resonance to the ρN channel. (orig.)

  9. Nucleonic gauging

    International Nuclear Information System (INIS)

    Bond, A.

    1977-01-01

    The present position of nucleonic techniques for process measurements, is considered from the technical and cost viewpoints. Systems considered include level, density, thickness (including coating thickness), moisture, and sulphur in hydrocarbons gauges and also belt weighers. The advantages of such systems are discussed and the cost-benefit position considered. The combination of nucleonic measuring equipment with a microcomputer is examined. (U.K.)

  10. 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.

  11. Quarks and partons

    International Nuclear Information System (INIS)

    Paschos, E.A.

    1976-08-01

    The quark parton model describes the inclusive electro- and neutrino production data if a clear distinction is made between reactions which take place at high and at low energies. For the low energy region the classical view of six structure functions of the proton is still adequate. For the high energy region models can be constructed which are consistent with the experimental data. (BJ) [de

  12. mu. -nucleon atoms

    Energy Technology Data Exchange (ETDEWEB)

    Dobretsov, Yu; Dolgoshein, B; Kirillov-Ugryumov, V

    1980-12-01

    The properties and formation are described of ..mu..-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of ..mu..-nucleon atoms is shown. The prospects of their use are indicated.

  13. Inequalities and bounds for nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Ramandurai, K.S.

    1979-08-01

    The objective of this work is to derive model-independent inequalities and bounds for nucleon-nucleon elastic scattering amplitudes based on well-established theoretical principles and symmetries. Two classes of methods are used: algebraic and variational. In the algebraic part, the author derives inequalities and bounds for NN amplitudes and observables using their mutual relations and x symmetries. In the variational part, he employs Lagrange's method of undetermined multipliers to evaluate the bounds. He tests the predictions of a sample of proposed phase shifts at three different energies using the results obtained

  14. The quark model and the nature of the repulsive core of the nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Faessler, A.; Fernandez, F.; Luebeck, G.; Shimizu, K.

    1982-01-01

    The nature of the repulsive core of the nucleon-nucleon is studied in the quark model. The resonating group equation for nucleon-nucleon scattering is solved with the colour Fermi-Breit interaction including further a linear or quadratic confinement potential. It is shown that the colour magnetic interaction which is adjusted to the Δ-nucleon mass splitting favours the orbital symmetry and disfavours the completely symmetric orbital state. For the important orbital symmetry the relative S wave function between the two nucleons has to have a node. In the framework of the resonating group including the NN, ΔΔ and the hidden colour (CC) channels it is shown that this node produces a 3 S and 1 S phase shift which is identical to a hard core phase shift with a hard core radius γ 0 between 0.3 and 0.6 fm depending on the assumed root mean square radius of the quark part of the nucleon. (orig./HSI)

  15. μ-nucleon atoms

    International Nuclear Information System (INIS)

    Dobretsov, Yu.; Dolgoshejn, B.; Kirillov-Ugryumov, V.

    1980-01-01

    The properties and formation are described of μ-nucleon atoms, the Larmor method of muon spin precession is discussed and the experimental confirmation of the existence of μ-nucleon atoms is shown. The prospects of their use are indicated. (J.P.)

  16. Double polarized neutron-proton scattering and nucleon-nucleon tensor force: An alternative analysis

    International Nuclear Information System (INIS)

    Tornow, W.; Gould, C.R.; Haase, D.G.; Walston, J.R.; Raichle, B.W.

    2002-01-01

    Previous neutron-proton total cross-section difference measurements Δσ L and Δσ T between E n =7.43 and 17.1 MeV have been analyzed in a new way that reduces experimental systematic uncertainties. The results obtained for the 3 S 1 - 3 D 1 mixing parameter ε 1 are very similar to the published values, substantiating the previous conclusion that the nucleon-nucleon tensor force at low energies is stronger than predicted by the Nijmegen partial-wave analysis and, therefore, by all the recent high-precision nucleon-nucleon potential models as well

  17. The nucleon-nucleon spin-orbit interaction in the Skyrme model

    International Nuclear Information System (INIS)

    Riska, D.O.; Dannbom, K.

    1987-01-01

    The spin-orbit and quadratic spin-orbit components of the nucleon-nucleon interaction are derived in the Skyrme model at the classical level. These interaction components arise from the orbital and rotational motion of the soliton fields that form the nucleons. The isospin dependent part of the spin-orbit interaction is similar to the corresponding component obtained from boson exchange mechanisms at long distances although at short distances it is weaker. The isospin independent spin-orbit component is however different from the prediction of boson exchange mechanisms and has the opposite sign. The quadratic spin-orbit interaction is weak and has only an isospin dependent component

  18. Gravitational form factors and angular momentum densities in light-front quark-diquark model

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Narinder [Indian Institute of Technology Kanpur, Department of Physics, Kanpur (India); Mondal, Chandan [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China); Sharma, Neetika [I K Gujral Punjab Technical University, Department of Physical Sciences, Jalandhar, Punjab (India); Panjab University, Department of Physics, Chandigarh (India)

    2017-12-15

    We investigate the gravitational form factors (GFFs) and the longitudinal momentum densities (p{sup +} densities) for proton in a light-front quark-diquark model. The light-front wave functions are constructed from the soft-wall AdS/QCD prediction. The contributions from both the scalar and the axial vector diquarks are considered here. The results are compared with the consequences of a parametrization of nucleon generalized parton distributions (GPDs) in the light of recent MRST measurements of parton distribution functions (PDFs) and a soft-wall AdS/QCD model. The spatial distribution of angular momentum for up and down quarks inside the nucleon has been presented. At the density level, we illustrate different definitions of angular momentum explicitly for an up and down quark in the light-front quark-diquark model inspired by AdS/QCD. (orig.)

  19. Database of Nucleon-Nucleon Scattering Cross Sections by Stochastic Simulation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A database of nucleon-nucleon elastic differential and total cross sections will be generated by stochastic simulation of the quantum Liouville equation in the...

  20. 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.

  1. Hadron Azimuthal Correlations and Mach-like Structures in a Partonic/Hadronic Transport Model

    International Nuclear Information System (INIS)

    Ma, G.L.; Zhang, S.; Ma, Y.G.; Cai, X.Z.; Chen, J.H.; He, Z.J.; Huang, H.Z.; Long, J.L.; Shen, W.Q.; Shi, X.H.; Zhong, C.; Zuo, J.X.

    2007-01-01

    With a multi-phase transport model (AMPT) with both partonic and hadronic interactions, two- and three-particle azimuthal correlations in Au + Au collisions at s NN =200 GeV have been studied by the mixing-event technique. A Mach-like structure has been observed in two- and three-particle correlations in central collisions. It has been found that both partonic and hadronic dynamical mechanisms contribute to the Mach-like structure. However, only hadronic rescattering is unable to reproduce experimental amplitude of Mach-like structure, and parton cascade process is indispensable. The results of three-particle correlation indicate a partonic Mach-like shock wave can be produced by strong parton cascade in central Au+Au collisions

  2. 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.)

  3. Do phase-shift analyses and nucleon-nucleon potential models yield the wrong 3Pj phase shifts at low energies?

    International Nuclear Information System (INIS)

    Tornow, W.; Witala, H.; Kievsky, A.

    1998-01-01

    The 4 P J waves in nucleon-deuteron scattering were analyzed using proton-deuteron and neutron-deuteron data at E N =3 MeV. New sets of nucleon-nucleon 3 P j phase shifts were obtained that may lead to a better understanding of the long-standing A y (θ) puzzle in nucleon-deuteron elastic scattering. However, these sets of 3 P j phase shifts are quite different from the ones determined from both global phase-shift analyses of nucleon-nucleon data and nucleon-nucleon potential models. copyright 1998 The American Physical Society

  4. Evaluation of the three-nucleon analyzing power puzzle

    International Nuclear Information System (INIS)

    Tornow, W.; Witala, H.

    1998-01-01

    The current status of the three-nucleon analyzing power puzzle is reviewed. Applying tight constraints on the allowed deviations between calculated predictions and accepted values for relevant nucleon-nucleon observables reveals that energy independent correction factors applied to the 3 P j nucleon-nucleon interactions can not solve the puzzle. Furthermore, using the same constraints, charge-independence breaking in the 3 P j nucleon-nucleon interactions can be ruled out as a possible tool to improve the agreement between three-nucleon calculations and data. The study of the energy dependence of the three-nucleon analyzing power puzzle gives clear evidence that the 3 P j nucleon-nucleon interaction obtained from phase-shift analyses and used in potential models are correct above about 25 MeV, i.e., the 3 P j nucleon-nucleon interactions have to be modified only at lower energies in order to solve the three-nucleon analyzing power puzzle, unless new three-nucleon forces can be found that account for the three-nucleon analyzing power puzzle without destroying the beautiful agreement between rigorous three-nucleon calculations and a large body of accurate three-nucleon data. (orig.)

  5. Evaluation of the three-nucleon analyzing power puzzle

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, W. [Duke Univ., Durham, NC (United States). Dept. of Physics]|[Triangle Univ. Nuclear Lab., Durham, NC (United States); Witala, H. [Uniwersytet Jagiellonski, Cracow (Poland). Inst. Fizyki

    1998-07-20

    The current status of the three-nucleon analyzing power puzzle is reviewed. Applying tight constraints on the allowed deviations between calculated predictions and accepted values for relevant nucleon-nucleon observables reveals that energy independent correction factors applied to the {sup 3}P{sub j} nucleon-nucleon interactions can not solve the puzzle. Furthermore, using the same constraints, charge-independence breaking in the {sup 3}P{sub j} nucleon-nucleon interactions can be ruled out as a possible tool to improve the agreement between three-nucleon calculations and data. The study of the energy dependence of the three-nucleon analyzing power puzzle gives clear evidence that the {sup 3}P{sub j} nucleon-nucleon interaction obtained from phase-shift analyses and used in potential models are correct above about 25 MeV, i.e., the {sup 3}P{sub j} nucleon-nucleon interactions have to be modified only at lower energies in order to solve the three-nucleon analyzing power puzzle, unless new three-nucleon forces can be found that account for the three-nucleon analyzing power puzzle without destroying the beautiful agreement between rigorous three-nucleon calculations and a large body of accurate three-nucleon data. (orig.) 18 refs.

  6. Covariant computation of e+e- production in nucleon-nucleon collisions

    International Nuclear Information System (INIS)

    Haglin, K.; Kapusta, J.; Gale, C.

    1989-01-01

    Electron-positron production differential cross sections in nucleon-nucleon collisions are calculated analytically via meson exchange with a realistic pseudovector coupling including strong interaction form factors. These results are compared with newly obtained data from the DLS at the BEVALAC of proton on beryllium. A comparison with the soft photon approximation is also made. (orig.)

  7. Relativistic one-boson-exchange model for the nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Gross, F.; Van Orden, J.W.; Holinde, K.

    1992-01-01

    Nucleon-nucleon data below 300-MeV laboratory energy are described by a manifestly covariant wave equation in which one of the intermediate nucleons is restricted to its mass shell. Antisymmetrization of the kernel yields an equation in which the two nucleons are treated in an exactly symmetric manner, and in which all amplitudes satisfy the Pauli principle exactly. The kernel is modeled by the sum of one boson exchanges, and four models, all of which fit the data very well (χ 2 congruent 3 per data point) are discussed. Two models require the exchange of only the π, σ, ρ, and ω, but also require an admixture of γ 5 coupling for the pion, while two other models restrict the pion coupling to pure γ 5 γ μ , but require the exchange of six mesons, including the η, and a light scalar-isovector meson referred to as σ 1 . Deuteron wave functions resulting from these models are obtained. The singularities and relativistic effects which are a part of this approach are discussed, and a complete development of the theory is presented

  8. Pre-equilibrium parton dynamics: Proceedings

    International Nuclear Information System (INIS)

    Wang, Xin-Nian

    1993-01-01

    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

  9. 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.

  10. Pion-nucleon vertex function with an off-shell nucleon

    International Nuclear Information System (INIS)

    Nutt, W.T.; Shakin, C.M.

    1977-01-01

    A model calculation for the π-N vertex function is presented in the case in which there is a single off-mass-shell nucleon and a (nearly) on-mass-shell pion. Very strong effects due to the P 11 resonance at 1470 MeV are found. A simple parametrization of the vertex function is prvided in the case that at least one nucleon is on its mass shell. (Auth.)

  11. Universality of many-body two-nucleon momentum distributions: Correlated nucleon spectral function of complex nuclei

    Science.gov (United States)

    Ciofi degli Atti, Claudio; Morita, Hiko

    2017-12-01

    Background: The nuclear spectral function is a fundamental quantity that describes the mean-field and short-range correlation dynamics of nucleons embedded in the nuclear medium; its knowledge is a prerequisite for the interpretation of various electroweak scattering processes off nuclear targets aimed at providing fundamental information on strong and weak interactions. Whereas in the case of the three-nucleon and, partly, the four-nucleon systems, the spectral function can be calculated ab initio within a nonrelativistic many-body Schroedinger approach, in the case of complex nuclei only models of the correlated, high-momentum part of the spectral function are available so far. Purpose: The purpose of this paper is to present a new approach such that the spectral function for a specific nucleus can be obtained from a reliable many-body calculation based upon realistic nucleon-nucleon interactions, thus avoiding approximations leading to adjustable parameters. Methods: The expectation value of the nuclear many-body Hamiltonian, containing realistic nucleon-nucleon interaction of the Argonne family, is evaluated variationally by a normalization-conserving linked-cluster expansion and the resulting many-body correlated wave functions are used to calculate the one-nucleon and the two-nucleon momentum distributions; by analyzing the high-momentum behavior of the latter, the spectral function can be expressed in terms of a transparent convolution formula involving the relative and center-of-mass (c.m.) momentum distributions in specific regions of removal energy E and momentum k . Results: It is found that as a consequence of the factorization of the many-body wave functions at short internucleon separations, the high-momentum behavior of the two-nucleon momentum distributions in A =3 ,4 ,12 ,16 ,40 nuclei factorizes, at proper values of the relative and c.m. momenta, into the c.m. and relative momentum distributions, with the latter exhibiting a universal A

  12. Axial structure of the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner

    2002-01-01

    We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.

  13. A parton shower based on factorization of the quantum density matrix

    OpenAIRE

    Nagy, Zoltan; Soper, Davison E.

    2014-01-01

    We present first results from a new parton shower event generator, D eductor . Anticipating a need for an improved treatment of parton color and spin, the structure of the generator is based on the quantum density matrix in color and spin space. So far, D eductor implements only a standard spin-averaged treatment of spin in parton splittings. Although D eductor implements an improved treatment of color, in this paper we present results in the standard leading color approximation so that we ca...

  14. Instanton partons in 5-dimensional SU(N) gauge theory

    International Nuclear Information System (INIS)

    Bolognesi, Stefano; Lee, Kimyeong

    2011-01-01

    The circle compactification of the 6-dimensional (2,0) superconformal theory of A N-1 type leads to the 5-dimensional SU(N) maximally supersymmetric gauge theory. Instanton solitons embody Kaluza-Klein modes and are conjectured to be composed of partonic constituents. We realize such a parton of 1/N instanton topological charge at the intersection of magnetic flux sheets. After a further compactification with nontrivial Wilson-line expectation value, instantons or calorons have been shown to be split into fundamental monopoles of fractional instanton charge. In the symmetric phase with trivial Wilson-line expectation value, Bogomol'nyi-Prasad-Sommerfield instanton partons emerge more concretely as non-Abelian Bogomol'nyi-Prasad-Sommerfield monopoles of minimum charge allowed in Dirac quantization.

  15. 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.

  16. 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.

  17. The nucleon-nucleon potential in the chromodielectric soliton model

    International Nuclear Information System (INIS)

    Koepf, W.; Wilets, L.; Pepin, S.; Stancu, F.

    1993-01-01

    The short- and medium-range parts of the nucleon-nucleon interaction are being studied in the framework of the chromodielectric soliton model. The model consists of current quarks, gluons in the abelian approximation, and a scalar σ field which simulates the nonabelian interactions of the gluons and governs the medium through the dielectric function κ(σ). Absolute color confinement is effected by the vanishing of the dielectric in vacuum; this also removes the troublesome van der Waals problem. The authors distinguish between spatial confinement, which arises from the self energy of the quarks in medium (excluding MFA contributions), and color confinement which is effected through OGE in the MFA (including the corresponding self energy contributions). The static (adiabatic) energies are computed as a function of deformation (generalized bag separation) in a constrained MFA. Six quark molecular-type wave functions in all important space-spin-isospin-color configurations are included. The gluon propagator is solved in the deformed dielectric medium. The resultant Hamiltonian matrix is diagonalized. Dynamics are handled in the Generator Coordinate Method, which leads to the Hill-Wheeler integral equation. In the present case, this yields a set of coupled equations corresponding to the various configurations. Although this can be approximated by a set of differential equations, they propose to solve the integral equations with some regularization scheme

  18. 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.

  19. Three-particle correlations from parton cascades in Au+Au collisions

    International Nuclear Information System (INIS)

    Ma, G.L.; Ma, Y.G.; Zhang, S.; Cai, X.Z.; Chen, J.H.; He, Z.J.; Huang, H.Z.; Long, J.L.; Shen, W.Q.; Shi, X.H.; Zhong, C.; Zuo, J.X.

    2007-01-01

    We present a study of three-particle correlations among a trigger particle and two associated particles in Au+Au collisions at s NN =200 GeV using a multi-phase transport model (AMPT) with both partonic and hadronic interactions. We found that three-particle correlation densities in different angular directions with respect to the triggered particle ('center', 'cone', 'deflected', 'near' and 'near-away') increase with the number of participants. The ratio of 'deflected' to 'cone' density approaches to 1.0 with the increasing of number of participants, which indicates that partonic Mach-like shock waves can be produced by strong parton cascades in central Au+Au collisions

  20. Probing nuclear structure with nucleons; Sonder la structure nucleaire avec des nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Bauge, E. [CEA Bruyeres-le-Chatel, Service de Physique Nucl aire, 91 (France)

    2007-07-01

    The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)

  1. p-wave pion production from nucleon-nucleon collisions

    International Nuclear Information System (INIS)

    Baru, V.; Epelbaum, E.; Haidenbauer, J.; Hanhart, C.; Kudryavtsev, A. E.; Lensky, V.; Meissner, U.-G.

    2009-01-01

    We investigate p-wave pion production in nucleon-nucleon collisions up to next-to-next-to-leading order in chiral effective field theory. In particular, we show that it is possible to describe simultaneously the p-wave amplitudes in the pn→ppπ - , pp→pnπ + , pp→dπ + channels by adjusting a single low-energy constant accompanying the short-range operator that is available at this order. This study provides a nontrivial test of the applicability of chiral effective field theory to reactions of the type NN→NNπ.

  2. Systematic improvement of parton showers with effective theory

    International Nuclear Information System (INIS)

    Baumgart, Matthew; Marcantonini, Claudio; Stewart, Iain W.

    2011-01-01

    We carry out a systematic classification and computation of next-to-leading order kinematic power corrections to the fully differential cross section in the parton shower. To do this we devise a map between ingredients in a parton shower and operators in a traditional effective field theory framework using a chain of soft-collinear effective theories. Our approach overcomes several difficulties including avoiding double counting and distinguishing approximations that are coordinate choices from true power corrections. Branching corrections can be classified as hard-scattering, that occur near the top of the shower, and jet-structure, that can occur at any point inside it. Hard-scattering corrections include matrix elements with additional hard partons, as well as power suppressed contributions to the branching for the leading jet. Jet-structure corrections require simultaneous consideration of potential 1→2 and 1→3 branchings. The interference structure induced by collinear terms with subleading powers remains localized in the shower.

  3. 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.

  4. Nucleon-Nucleon Potentials and Computation of Scattering Phase Shifts

    Directory of Open Access Journals (Sweden)

    Jhasaketan Bhoi

    2015-12-01

    Full Text Available By judicious exploitation of supersymmetry formalism of quantum mechanics higher partial wave nucleon-nucleon potentials are generated from its ground state interactions. The nuclear Hulthen potential and the corresponding ground state wave function with the parameters of Arnold and MacKellar are used as the starting point of our calculation. We compute the scattering phase shifts for our constructed potentials through Phase Function Method to examine the merit of our approach to the problem.

  5. Scattering by bound nucleons

    International Nuclear Information System (INIS)

    Tezuka, Hirokazu.

    1984-10-01

    Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)

  6. Unbiased Polarised Parton Distribution Functions and their Uncertainties

    CERN Document Server

    Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan

    2012-01-01

    We present preliminary results on the determination of spin-dependent, or polarised, Parton Distribution Functions (PDFs) from all relevant inclusive polarised DIS data. The analysis is performed within the NNPDF approach, which provides a faithful and statistically sound representation of PDFs and their uncertainties. We describe how the NNPDF methodology has been extended to the polarised case, and compare our results with other recent polarised parton sets. We show that polarised PDF uncertainties can be sizeably underestimated in standard determinations, most notably for the gluon.

  7. Are partons confined tachyons?

    International Nuclear Information System (INIS)

    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 2 > c 2 , without conflict with the observational fact that neither quarks nor tachyons have appeared as ''free particles''. Some consequences of this model are explored

  8. 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.

  9. The transverse-energy distributions of 32S-nucleus collisions at 200 GeV per nucleon

    International Nuclear Information System (INIS)

    Akesson, T.; Atherton, H.; Beker, H.; Bettoni, D.; Boeggild, H.; Dederichs, K.; Devenish, R.C.E.; En'yo, H.; Esten, M.J.; Fabjan, C.W.; Mazzoni, M.A.; Nilsson, S.; Piuz, F.; Poulard, G.; Price, M.; Russ, J.; Schukraft, J.; Sekimoto, M.; Seman, M.; Shotton, P.; Sletten, H.; Thodberg, H.H.; Veenhof, R.; Wigmans, R.; Willis, W.; Almehed, S.; Haglund, R.; Hedeberg, V.; Johansson, S.; Loerstad, B.; Mjoernmark, U.; Angelis, A.L.S.; Dodd, J.R.; Lessard, L.; McCubbin, M.L.; Armenise, N.; Muciaccia, M.T.; Simone, S.; Aubry, P.; Beaudoin, G.; Beaulieu, J.M.; Depommier, P.; Lounis, A.; Bartels, H.W.; Drees, A.; Fischer, P.; Glaessel, P.; Goerlach, U.; Hoelscher, A.; Kroh, V.; Neubert, M.; Pfeiffer, A.; Specht, H.J.; Benary, O.; Dagan, S.; Heifetz, R.; Marzari-Chiesa, A.; Masera, M.; Oren, Y.; Bisi, V.; Giubellino, P.; Ramello, L.; Riccati, L.; Blevis, I.; Fraenkel, Z.; Tserruya, I.; Cleland, W.; Clemen, M.; Collick, B.; Murray, M.; Park, Y.M.; Thompson, J.; Corriveau, F.; Hamel, L.A.; Jarlskog, G.; Lamarche, F.; Leroy, C.; Mazzucato, E.; Sirois, Y.; Dell'Uomo, S.; Di Liberto, S.; Meddi, F.; Rosa, G.; DiGiacomo, N.; Van Hecke, H.; Jacak, B.; McGaughey, P.; Sondheim, W.; Sunier, J.; Dolgoshein, B.; Kalinovski, A.; Kantserov, A.; Nevski, P.; Smirnov, S.; Sumarokov, A.; Tcherniatin, V.; Tikhomirov, V.; Berlandsson, B.; Sellden, B.; Gaidot, A.; Gibrat-Debu, F.; London, G.; Pansart, J.P.; Vasseur, G.; McCubbin, N.A.; Romano, G.; Sidorov, V.

    1988-01-01

    Transverse-energy distributions have been measured for the collisions of the 32 S nucleus with Al, Ag, W, Pt, Pb and U target nuclei, at an incident energy of 200 GeV per nucleon. The shapes of these distribution reflect the geometry of the collisions, including the deformation effects. For central collisions, the transverse-energy production in the region -0.1 lab 0.5 , where A is the atomic mass number of the target. This increase is accompanied by a relative depletion in the forward region η lab > 2.9. These results are compared with those obtained under similar conditions with incident 16 O nuclei. A comparison is also made with the predictions of a Monte Carlo generator based on the dual parton model. Finally, we give estimates of the energy density reached and its dependence on the atomic mass number of the projectile. (orig.)

  10. Parton-shower matching systematics in vector-boson-fusion WW production

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, Michael [Karlsruhe Institute of Technology, Institute for Theoretical Physics, Karlsruhe (Germany); Plaetzer, Simon [Durham University, Institute for Particle Physics Phenomenology, Durham (United Kingdom); University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom)

    2017-05-15

    We perform a detailed analysis of next-to-leading order plus parton-shower matching in vector-boson-fusion WW production including leptonic decays. The study is performed in the Herwig 7 framework interfaced to VBFNLO 3, using the angular-ordered and dipole-based parton-shower algorithms combined with the subtractive and multiplicative-matching algorithms. (orig.)

  11. Survey of structures revealed in nucleon-nucleon scattering experiments and dibaryon resonances

    International Nuclear Information System (INIS)

    Hidaka, K.; Yokosawa, A.

    1979-01-01

    Structures appearing in various experimental data (particularly those with polarized beams) in nucleon-nucleon systems are reviewed. Evidence is presented for the existence of dibaryon resonances with an emphasis on a diproton resonance in 3 F 3 (J/sup P/ = 3 - ) state. 38 references

  12. A separable approach to the Bethe-Salpeter equation and its application to nucleon-nucleon scattering

    International Nuclear Information System (INIS)

    Schwarz, K.; Froehlich, J.; Zingl, H.F.K.

    1980-01-01

    The Bethe-Salpeter equation is solved in closed form with the help of a four dimensional separable 'potential'. For possible applications to three-nucleon investigations the authors have fitted all nucleon-nucleon S-wave phase shifts in a sufficient way by this method; in addition they also present an example for a P-wave. (Auth.)

  13. Polarized 3 parton production in inclusive DIS at small x

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, Alejandro [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, Ciudad de México 04510 (Mexico); Centre for Theoretical and Mathematical Physics, and Department of Physics, University of Cape Town, Rondebosch 7700 (South Africa); Hentschinski, Martin, E-mail: hentschinski@correo.nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, Ciudad de México 04510 (Mexico); Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla 1152 (Mexico); Jalilian-Marian, Jamal [Department of Natural Sciences, Baruch College, CUNY, 17 Lexington Avenue, New York, NY 10010 (United States); CUNY Graduate Center, 365 Fifth Avenue, New York, NY 10016 (United States); Tejeda-Yeomans, Maria Elena [Departamento de Física, Universidad de Sonora, Boulevard Luis Encinas J. y Rosales, Colonia Centro, Hermosillo, Sonora 83000 (Mexico)

    2016-10-10

    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.

  14. Polarized 3 parton production in inclusive DIS at small x

    International Nuclear Information System (INIS)

    Ayala, Alejandro; Hentschinski, Martin; Jalilian-Marian, Jamal; Tejeda-Yeomans, Maria Elena

    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. 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.

  15. Four-nucleon system with Δ-isobar excitation

    International Nuclear Information System (INIS)

    Deltuva, A.; Fonseca, A.C.; Sauer, P.U.

    2008-01-01

    The four-nucleon bound state and scattering below three-body breakup threshold are described based on the realistic coupled-channel potential CD Bonn+Δ which allows the excitation of a single nucleon to a Δ isobar. The Coulomb repulsion between protons is included. In the four-nucleon system the two-baryon coupled-channel potential yields effective two-, three- and four-nucleon forces, mediated by the Δ isobar and consistent with each other and with the underlying two-nucleon force. The effect of the four-nucleon force on the studied observables is much smaller than the effect of the three-nucleon force. The inclusion of the Δ isobar is unable to resolve the existing discrepancies with the experimental data

  16. Nucleon structure in view of recent developments

    International Nuclear Information System (INIS)

    Martin, A.D.

    1993-01-01

    We review the present knowledge of the parton structure of the proton. We discuss recent developments concerning deep-inelastic scattering and parton distributions at small x, with emphasis on the predictions of perturbative QCD that are relevant to the experiment at HERA. (author). 37 refs, 16 figs, 1 tab

  17. Statistical properties of antisymmetrized molecular dynamics for non-nucleon-emission and nucleon-emission processes

    International Nuclear Information System (INIS)

    Ono, A.; Horiuchi, H.

    1996-01-01

    Statistical properties of antisymmetrized molecular dynamics (AMD) are classical in the case of nucleon-emission processes, while they are quantum mechanical for the processes without nucleon emission. In order to understand this situation, we first clarify that there coexist mutually opposite two statistics in the AMD framework: One is the classical statistics of the motion of wave packet centroids and the other is the quantum statistics of the motion of wave packets which is described by the AMD wave function. We prove the classical statistics of wave packet centroids by using the framework of the microcanonical ensemble of the nuclear system with a realistic effective two-nucleon interaction. We show that the relation between the classical statistics of wave packet centroids and the quantum statistics of wave packets can be obtained by taking into account the effects of the wave packet spread. This relation clarifies how the quantum statistics of wave packets emerges from the classical statistics of wave packet centroids. It is emphasized that the temperature of the classical statistics of wave packet centroids is different from the temperature of the quantum statistics of wave packets. We then explain that the statistical properties of AMD for nucleon-emission processes are classical because nucleon-emission processes in AMD are described by the motion of wave packet centroids. We further show that when we improve the description of the nucleon-emission process so as to take into account the momentum fluctuation due to the wave packet spread, the AMD statistical properties for nucleon-emission processes change drastically into quantum statistics. Our study of nucleon-emission processes can be conversely regarded as giving another kind of proof of the fact that the statistics of wave packets is quantum mechanical while that of wave packet centroids is classical. copyright 1996 The American Physical Society

  18. Charge dependence and charge asymmetry in the nucleon-nucleon interaction due to processes involving Δ's

    International Nuclear Information System (INIS)

    Wells, T.B.

    1978-01-01

    The charge dependence and charge asymmetry of the nucleon-nucleon force arising from the exchange of a pion and a photon with the excitation of a nucleon resonance [Δ(1236)] is calculated. This charge dependence and asymmetry is studied through its effects on the 1 S nucleon-nucleon scattering lengths. The complexity of the calculation forces the use of approximations. The calculation is performed first with a pole approximation for the resonance and a second time with a Chew-Low description of the resonance. Both calculations neglect nuclear recoil. Estimates of this effect are made. The changes in the scattering lengths are small ( +- / 2 = 1.0225 G/sub π 0 / 2 will explain the proton-neutron scattering length

  19. The nucleon-nucleon interaction in the presence of the electromagnetic field: Nucleon-nucleon bremsstrahlung

    International Nuclear Information System (INIS)

    Brown, V.R.

    1990-01-01

    Nucleon-nucleon bremsstrahlung, NNγ, is a fundamental process, which involves the strong and electromagnetic fields acting simultaneously. Since the electromagnetic interaction is well known, NNγ provides a calculable tool for comparing off-energy-shell effects from different two-nucleon potentials compared to experiment and also provides a simple testing ground, which is sensitive to meson-exchange-current contributions that are so important in electronuclear physics. Historically, experimental studies have focused on ppγ, with only a few measurements of npγ. The present workshop was organized primarily to investigate the interest in, the value of, and the feasibility of doing an npγ experiment using the neutron white source at LANL. An increasing amount of US nuclear physics dollars are being spent on electronuclear physics. npγ is a fundamental process with large meson-exchange currents. In the npγ calculations of Brown and Franklin, the meson-exchange contributions increase the cross section by a factor of roughly two and later the angular distribution of the emitted photon dramatically. The details of these calculated effects have never been verified experimentally, but the proper quantum-mechanical inclusion of meson-exchange contributions, using the methods of brown and Franklin, has proved to be essential in understanding the heavy-ion results. The understanding of the importance of such terms is extremely important inelectronuclear processes, such as are presently under investigation or being planned at Bates, SLAC, and CEBAF. Just one example is in the electrodisintegration of the deuteron, where meson-exchange contributions must be included properly before any conclusions about nuclear models, such as QCD versus meson-exchange potentials can be made

  20. Induced hyperon-nucleon-nucleon interactions and the hyperon puzzle

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, Roland; Roth, Robert [Institut fuer Kernphysik, TU Darmstadt (Germany)

    2016-07-01

    There is a strong experimental and theoretical interest in determining the structure of hypernuclei and the effect of strangeness in strongly interacting many-body systems. Recently, we presented the first calculations of hypernuclei in the p shell from first principles. However, these calculations showed either slow convergence with respect to model-space size or, when the hyperon-nucleon potential is transformed via the Similarity Renormalization Group, strong induced three-body terms. By including these induced hyperon-nucleon-nucleon (YNN) terms explicitly, we get precise binding and excitation energies. We present first results for p-shell hypernuclei and discuss the origin of the YNN terms, which are mainly driven by the evolution of the Λ-Σ conversion terms. We find that they are tightly connected to the hyperon puzzle, a long-standing issue where the appearance of hyperons in models of neutron star matter lowers the predicted maximum neutron star mass below the bound set by the heaviest observed objects.

  1. A parton shower based on factorization of the quantum density matrix

    International Nuclear Information System (INIS)

    Nagy, Zoltan; Soper, Davison E.

    2014-01-01

    We present rst results from a new parton shower event generator, DEDUCTOR. Anticipating a need for an improved treatment of parton color and spin, the structure of the generator is based on the quantum density matrix in color and spin space. So far, DEDUCTOR implements only a standard spin-averaged treatment of spin in parton splittings. Although DEDUCTOR implements an improved treatment of color, in this paper we present results in the standard leading color approximation so that we can compare to the generator PYTHIA. The algorithms used incorporate a virtuality based shower ordering parameter and massive initial state bottom and charm quarks.

  2. Geometrical parton

    Energy Technology Data Exchange (ETDEWEB)

    Ebata, T [Tohoku Univ., Sendai (Japan). Coll. of General Education

    1976-06-01

    The geometrical distribution inferred from the inelastic cross section is assumed to be proportional to the partial waves. The precocious scaling and the Q/sup 2/-dependence of various quantities are treated from the geometrical point of view. It is shown that the approximate conservation of the orbital angular momentum may be a very practical rule to understand the helicity structure of various hadronic and electromagnetic reactions. The rule can be applied to inclusive reactions as well. The model is also applied to large angle processes. Through the discussion, it is suggested that many peculiar properties of the quark-parton can be ascribed to the geometrical effects.

  3. Scale breaking effects in the quark-parton model for large P perpendicular phenomena

    International Nuclear Information System (INIS)

    Baier, R.; Petersson, B.

    1977-01-01

    We discuss how the scaling violations suggested by an asymptotically free parton model, i.e., the Q 2 -dependence of the transverse momentum of partons within hadrons may affect the parton model description of large p perpendicular phenomena. We show that such a mechanism can provide an explanation for the magnitude of the opposite side correlations and their dependence on the trigger momentum. (author)

  4. Analytic approach to the relativistic problem of constructing effective nucleon-nucleon and pion-nucleon interaction operators at low and intermediate energies

    International Nuclear Information System (INIS)

    Safronov, A.N.; Safronov, A.A.

    2006-01-01

    formation of a short-range repulsive core. In the given work this approach is generalized for constructing effective hadron-hadron interaction operators in framework multichannel formalism in arbitrary angular momentum states taking into account effects of inelasticity. The methods of taking into account mechanisms of formation a quark-gluon compound states in hadron-hadron interactions are elaborated also. The developed methods are applied to constructing nucleon-nucleon interaction operators in different partial-wave states. The boson-exchange model was used to calculate the discontinuities of the partial-wave scattering amplitudes taking into account π, σ, ρ, ω, η, a 0 -meson contributions. The effective nucleon-nucleon potentials in our approach (as against the one-boson-exchange model in usual sense) contain nonlinear contributions on dynamic discontinuities of partial-wave scattering amplitudes, which play essential role at small distances. Note that in realistic Bonn potential model [5] the short-range repulsion is due to ω-meson exchange contribution. It is required in this theory non-realistically large value (≅20 ) of the coupling constant g ωNN 2 /4π. The value of this coupling constant in our approach is consistent with available experimental data [6] and also with theoretical quark-model calculations. The theoretical predictions of the proposed approach are in fairly good agreement with partial-wave-analysis data for laboratory kinetic energies of incident nucleon up to T=1.5-2.0 GeV. The developed approach is applied also to pion-nucleon scattering at kinetic energies of incident pion up to T=2.0 GeV. This work was supported by the Russian Foundation for Basic Research under the project No 04-02-16967. (author)

  5. Skyrme-model πNN form factor and nucleon-nucleon interaction

    International Nuclear Information System (INIS)

    Holzwarth, G.; Machleidt, R.

    1997-01-01

    We apply the strong πNN form factor, which emerges from the Skyrme model, in the two-nucleon system using a one-boson-exchange (OBE) model for the nucleon-nucleon (NN) interaction. Deuteron properties and phase parameters of NN scattering are reproduced well. In contrast to the form factor of monopole shape that is traditionally used in OBE models, the Skyrme form factor leaves low-momentum transfers essentially unaffected while it suppresses the high-momentum region strongly. It turns out that this behavior is very appropriate for models of the NN interaction and makes it possible to use a soft pion form factor in the NN system. As a consequence, the πN and the NN systems can be described using the same πNN form factor, which is impossible with the monopole. copyright 1997 The American Physical Society

  6. Fusion reactor nucleonics: status and needs

    International Nuclear Information System (INIS)

    Lee, J.D.; Engholm, B.A.; Dudziak, D.J.; Haight, R.C.

    1980-01-01

    The national fusion technology effort has made a good start at addressing the basic nucleonics issues, but only a start. No fundamental nucleonics issues are seen as insurmountable barriers to the development of commercial fusion power. To date the fusion nucleonics effort has relied almost exclusively on other programs for nuclear data and codes. But as we progress through and beyond ETF type design studies the fusion program will need to support a broad based nucleonics effort including code development, sensitivity studies, integral experiments, data acquisition etc. It is clear that nucleonics issues are extremely important to fusion development and that we have only scratched the surface

  7. Why do nucleons cling. [Meson theory

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N [Hindu Coll., Delhi (India)

    1976-10-01

    The nature of the forces which bind nucleons together within the nucleus of an atom have been discussed in detail. The characteristic properties of the nucleons, such as spin, interaction range etc. and the meson theory of nuclear forces are described. The present researches indicate that the force between two nucleons in a many-nucleon system is not very different from the force between two free nucleons. Researches related to the origin of nuclear forces based on the meson theory are now mainly concerned with the role played by the heavier mesons and the two pion exchanges in the middle region around 0.7 fm. (10/sup -13/ cm).

  8. Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons

    Science.gov (United States)

    Howell, C. R.; Tornow, W.; Witała, H.

    2016-03-01

    The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL) is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.

  9. Comparative study of various methods of primary energy estimation in nucleon-nucleon interactions

    International Nuclear Information System (INIS)

    Goyal, D.P.; Yugindro Singh, K.; Singh, S.

    1986-01-01

    The various available methods for the estimation of primary energy in nucleon-nucleon interactions have been examined by using the experimental data on angular distributions of shower particles from p-N interactions at two accelerator energies, 67 and 400 GeV. Three different groups of shower particle multiplicities have been considered for interactions at both energies. It is found that the different methods give quite different estimates of primary energy. Moreover, each method is found to give different values of energy according to the choice of multiplicity groups. It is concluded that the E ch method is relatively the better method among all the methods available, and that within this method, the consideration of the group of small multiplicities gives a much better result. The method also yields plausible estimates of inelasticity in high energy nucleon-nucleon interactions. (orig.)

  10. Normal Spin Asymmetries in Elastic Electron-Proton Scattering

    International Nuclear Information System (INIS)

    M. Gorchtein; P.A.M. Guichon; M. Vanderhaeghen

    2004-01-01

    We discuss the two-photon exchange contribution to observables which involve lepton helicity flip in elastic lepton-nucleon scattering. This contribution is accessed through the single spin asymmetry for a lepton beam polarized normal to the scattering plane. We estimate this beam normal spin asymmetry at large momentum transfer using a parton model and we express the corresponding amplitude in terms of generalized parton distributions. We further discuss this observable in the quasi-RCS kinematics which may be dominant at certain kinematical conditions and find it to be governed by the photon helicity-flip RCS amplitudes

  11. Normal Spin Asymmetries in Elastic Electron-Proton Scattering

    International Nuclear Information System (INIS)

    Gorchtein, M.; Guichon, P.A.M.; Vanderhaeghen, M.

    2005-01-01

    We discuss the two-photon exchange contribution to observables which involve lepton helicity flip in elastic lepton-nucleon scattering. This contribution is accessed through the single spin asymmetry for a lepton beam polarized normal to the scattering plane. We estimate this beam normal spin asymmetry at large momentum transfer using a parton model and we express the corresponding amplitude in terms of generalized parton distributions. We further discuss this observable in the quasi-RCS kinematics which may be dominant at certain kinematical conditions and find it to be governed by the photon helicity-flip RCS amplitudes

  12. Comparison of parton distributions and structure functions for the proton

    International Nuclear Information System (INIS)

    Abramowicz, H.; Charchula, K.; Krawczyk, M.; Levy, A.

    1990-09-01

    A comparative study of the most popular parton parametrizations is presented. The individual parton distributions as well as the F 2 structure function are discussed with a particular emphasis on the low x region, 10 -4 -2 . The predictions of these parametrizations for the F 2 structure function have a wide spread which persists also in the HERA kinematical region. (orig.)

  13. Polarized 3 parton production in inclusive DIS at small x

    Directory of Open Access Journals (Sweden)

    Alejandro Ayala

    2016-10-01

    Full Text Available 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.

  14. The breaking of Bjorken scaling in the covariant parton model

    International Nuclear Information System (INIS)

    Polkinghorne, J.C.

    1976-01-01

    Scale breaking is investigated in terms of a covariant parton model formulation of deep inelastic processes. It is shown that a consistent theory requires that the convergence properties of parton-hadron amplitudes should be modified as well as the parton being given form factors. Purely logarithmic violation is possible and the resulting model has many features in common with asymtotically free gauge theories. Behaviour at large and small ω and fixed q 2 is investigated. γW 2 should increase with q 2 at large ω and decrease with q 2 at small ω. Heuristic arguments are also given which suggest that the model would only lead to logarithmic modifications of dimensional counting results in purely hadronic deep scattering. (Auth.)

  15. Hadron Correlations and Parton Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Fries, R.J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)]. E-mail: rjfries@comp.tamu.edu

    2007-02-15

    Parton recombination has been found to be an extremely useful model to understand hadron production at the Relativistic Heavy Ion Collider. It is particularly important to explore its connections with hard processes. This article reviews some of the aspects of the quark recombination model and places particular emphasis on hadron correlations.

  16. 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...

  17. Isospin Mixing in the Nucleon and 4He and the Nucleon Strange Electric Form Factor

    International Nuclear Information System (INIS)

    Viviani, M.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Rosati, S.; Schiavilla, R.; Kubis, B.; Lewis, R.

    2007-01-01

    In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4 He(e-vector,e ' ) 4 He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4 He. We examine this issue in the present Letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in 4 He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX Collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor

  18. Isospin mixing in the nucleon and He-4 and the nucleon strange electric form-factor

    International Nuclear Information System (INIS)

    M. Viviani; R. Schiavilla; B. Kubis; R. Lewis; L. Girlanda; A. Kievsky; L.E. Marcucci; S. Rosati

    2007-01-01

    In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4 He((rvec e),e(prime)) 4 He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4 He. We examine this issue in the present letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in 4 He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor

  19. The nucleon-nucleon correlations and the integral characteristics of the potential distributions in nuclei

    International Nuclear Information System (INIS)

    Knyaz'kov, O.M.; Kukhtina, I.N.

    1989-01-01

    The integral characteristics of the potential distribution in nuclei, namely the volume integrals, moments and mean square radii are studied in the framework of the semimicroscopic approach to the interaction of low energy nucleons with nuclei on the base of the exchange nucleon-nucleon correlations and the density dependence of effective forces. The ratio of the normalized multipole moments of potential and matter distributions is investigated. The energy dependence of the integral characteristics is analyzed. 15 refs.; 2 tabs

  20. Spin observables in nucleon-nucleus scattering

    International Nuclear Information System (INIS)

    Moss, J.M.

    1982-01-01

    The curse of inelastic nucleon scattering and charge exchange has always been the enormous complexity of the nucleon-nucleon (N-N) interaction. This complexity, however, can also be viewed as the ultimate promise of nucleons as probes of nuclear structure. Given an adequate theoretical basis, inelastic nucleon scattering is capable of providing information not obtainable with other probes. Recently a revolution of experimental technique has taken place that makes it desirable to re-examine the question of what physics is ultimately obtainable from inelastic nucleon scattering. It is now feasible to perform complete polarization transfer (PT) experiments for inelastic proton scattering with high efficiency and excellent energy resolution. Programs to measure PT obsevables are underway at several laboratories, and results are beginning to appear. Objectives of this presentation are to examine how such experiments are done, and what physics is presently obtained and may ultimately be learned from them

  1. Neutrino dimuon production and the strangeness asymmetry of the nucleon

    International Nuclear Information System (INIS)

    Olness, F.; Nadolsky, P.; Pumplin, J.; Stump, D.; Huston, J.; Tung, W.K.; Lai, H.L.; Kretzer, S.; Owens, J.F.

    2005-01-01

    We have performed the first global QCD analysis to include the CCFR and NuTeV dimuon data, which provide direct constraints on the strange and antistrange parton distributions, s(x) and anti s(x). To explore the strangeness sector, we adopt a general parametrization of the non-perturbative s(x), anti s(x) functions satisfying basic QCD requirements. We find that the strangeness asymmetry, as represented by the momentum integral [S - ]≡∫ 0 1 x [s(x)- anti s(x)] dx, is sensitive to the dimuon data provided the theoretical QCD constraints are enforced. We use the Lagrange multiplier method to probe the quality of the global fit as a function of [S - ] and find -0.001 - ] < 0.004. Representative parton distribution sets spanning this range are given. Comparisons with previous work are made. (orig.)

  2. Parton Distributions in the Higgs Boson Era

    CERN Document Server

    Rojo, Juan

    2013-01-01

    Parton distributions are an essential ingredient of the LHC program. PDFs are relevant for precision Standard Model measurements, for Higgs boson characterization as well as for New Physics searches. In this contribution I review recent progress in the determination of the parton distributions of the proton during the last year. Important developments include the impact of new LHC measurements to pin down poorly known PDFs, studies of theoretical uncertainties, higher order calculations for processes relevant for PDF determinations, PDF benchmarking exercises with LHC data, as well as methodological and statistical improvements in the global analysis framework. I conclude with some speculative considerations about future directions in PDF determinations from the theory point of view.

  3. Reconstruction of Monte Carlo replicas from Hessian parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Tie-Jiun [Department of Physics, Southern Methodist University,Dallas, TX 75275-0181 (United States); Gao, Jun [INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology,Department of Physics and Astronomy, Shanghai Jiao-Tong University, Shanghai 200240 (China); High Energy Physics Division, Argonne National Laboratory,Argonne, Illinois, 60439 (United States); Huston, Joey [Department of Physics and Astronomy, Michigan State University,East Lansing, MI 48824 (United States); Nadolsky, Pavel [Department of Physics, Southern Methodist University,Dallas, TX 75275-0181 (United States); Schmidt, Carl; Stump, Daniel [Department of Physics and Astronomy, Michigan State University,East Lansing, MI 48824 (United States); Wang, Bo-Ting; Xie, Ke Ping [Department of Physics, Southern Methodist University,Dallas, TX 75275-0181 (United States); Dulat, Sayipjamal [Department of Physics and Astronomy, Michigan State University,East Lansing, MI 48824 (United States); School of Physics Science and Technology, Xinjiang University,Urumqi, Xinjiang 830046 (China); Center for Theoretical Physics, Xinjiang University,Urumqi, Xinjiang 830046 (China); Pumplin, Jon; Yuan, C.P. [Department of Physics and Astronomy, Michigan State University,East Lansing, MI 48824 (United States)

    2017-03-20

    We explore connections between two common methods for quantifying the uncertainty in parton distribution functions (PDFs), based on the Hessian error matrix and Monte-Carlo sampling. CT14 parton distributions in the Hessian representation are converted into Monte-Carlo replicas by a numerical method that reproduces important properties of CT14 Hessian PDFs: the asymmetry of CT14 uncertainties and positivity of individual parton distributions. The ensembles of CT14 Monte-Carlo replicas constructed this way at NNLO and NLO are suitable for various collider applications, such as cross section reweighting. Master formulas for computation of asymmetric standard deviations in the Monte-Carlo representation are derived. A correction is proposed to address a bias in asymmetric uncertainties introduced by the Taylor series approximation. A numerical program is made available for conversion of Hessian PDFs into Monte-Carlo replicas according to normal, log-normal, and Watt-Thorne sampling procedures.

  4. Hadron muoproduction at the COMPASS experiment

    International Nuclear Information System (INIS)

    Rajotte, Jean-Francois

    2010-01-01

    The COMPASS Collaboration has two main fields of interest: to improve our knowledge of the nucleon spin structure and to study hadrons through spectroscopy. These goals require a multipurpose universal spectrometer such as the COmmon Muon and Proton Apparatus for Structure and Spectroscopy, COMPASS. In its first years of data taking (2002-2007), the nucleon spin structure was studied with a polarized muon beam scattering off a polarized target. These studies resumed in 2010 and will continue until at least 2011. The years 2008 and 2009 were dedicated to hadron spectroscopy using hadron beams. In the case of the nucleon structure studies, it is crucial to detect with high precision the incoming beam muon (160 GeV), the scattered muon and the produced hadrons. The large amount of high quality data accumulated provides access to the unpolarized and polarized parton distributions of the nucleon and the hadronization process. Subtle differences (asymmetries) between polarized cross sections have been predicted for hadron production from polarized muon-nucleon interaction for COMPASS. It is based on these differences that the polarized parton distributions can be measured. In this context, it is important to first compare predictions with the gross features of the measured unpolarized semi-inclusive differential cross sections or the closely related differential multiplicities. In order to determine cross sections, the data has to be corrected for the acceptance of the spectrometer. In this thesis, a multidimensional acceptance correction method, based on Monte Carlo simulation, is developed and applied to the data measured in 2004. The method is first used to determine the inclusive muon-nucleon cross section which is compared with a global fit to world data. This serves as a test of the acceptance correction method and to verify if the results from previous experiments can be reproduced. Then, unpolarized differential multiplicities as a function of transverse momentum

  5. Hadron muoproduction at the COMPASS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rajotte, Jean-Francois

    2010-09-30

    The COMPASS Collaboration has two main fields of interest: to improve our knowledge of the nucleon spin structure and to study hadrons through spectroscopy. These goals require a multipurpose universal spectrometer such as the COmmon Muon and Proton Apparatus for Structure and Spectroscopy, COMPASS. In its first years of data taking (2002-2007), the nucleon spin structure was studied with a polarized muon beam scattering off a polarized target. These studies resumed in 2010 and will continue until at least 2011. The years 2008 and 2009 were dedicated to hadron spectroscopy using hadron beams. In the case of the nucleon structure studies, it is crucial to detect with high precision the incoming beam muon (160 GeV), the scattered muon and the produced hadrons. The large amount of high quality data accumulated provides access to the unpolarized and polarized parton distributions of the nucleon and the hadronization process. Subtle differences (asymmetries) between polarized cross sections have been predicted for hadron production from polarized muon-nucleon interaction for COMPASS. It is based on these differences that the polarized parton distributions can be measured. In this context, it is important to first compare predictions with the gross features of the measured unpolarized semi-inclusive differential cross sections or the closely related differential multiplicities. In order to determine cross sections, the data has to be corrected for the acceptance of the spectrometer. In this thesis, a multidimensional acceptance correction method, based on Monte Carlo simulation, is developed and applied to the data measured in 2004. The method is first used to determine the inclusive muon-nucleon cross section which is compared with a global fit to world data. This serves as a test of the acceptance correction method and to verify if the results from previous experiments can be reproduced. Then, unpolarized differential multiplicities as a function of transverse momentum

  6. Pion distribution in the nucleon

    International Nuclear Information System (INIS)

    Lee, T.-S.H.

    1989-01-01

    A model is presented for calculating the pion wave function inside the nucleon. By assuming that all pions around a core of the nucleon are in the lowest eigenstate of the system, it is shown that both the bound state and πN scattering amplitude can be consistently described by an exactly soluble model defined in the subspace spanned by the core state and the physical πN state. The parameters of the model are determined by fitting the data of the nucleon mass, πNN coupling constant and low energy πN scattering phase shifts. The model predicts that the probability of finding the pion component inside the nucleon is about 20%. The calculated πNN form factor differs significantly from the conventional monopole form. The dynamical consequences of the differences are demonstrated in a calculation of electromagnetic production of pions from the nucleon and the deuteron. 7 refs., 4 figs., 1 tab

  7. Parton showers in a phenomenological context

    International Nuclear Information System (INIS)

    Bengtsson, M.

    1987-08-01

    Models for generating multiple parton final states, based on the Altarelli-Parisi equations, are presented. Algorithms are described for applications in e + e - physics, leptoproduction and hadron physics. The two latter cases are somewhat special since composite objects are present in the initial state. Constraints from structure function evolution are properly taken into account. The scheme in leptoproduction is made selfconsistent in the sense that parton shower evolution does not affect the measurable structure functions. The scheme developed in e + e - allows for a number of different features which are not given directly in this approach, i.e. matching onto matrix elements, coherence effects, argument in α s , implementation of kinematics etc. These options are systematically studied, using Lund string fragmentation for hadronization, and compared with experimental data. A note on α s determinations in hadron-hadron collisions is also included. (author)

  8. Multiple parton interactions at the LHC

    CERN Document Server

    Gaunt, Jonathan Richard

    2018-01-01

    Many high-energy collider experiments (including the current Large Hadron Collider at CERN) involve the collision of hadrons. Hadrons are composite particles consisting of partons (quarks and gluons), and this means that in any hadron–hadron collision there will typically be multiple collisions of the constituents — i.e. multiple parton interactions (MPI). Understanding the nature of the MPI is important in terms of searching for new physics in the products of the scatters, and also in its own right to gain a greater understanding of hadron structure. This book aims at providing a pedagogical introduction and a comprehensive review of different research lines linked by an involvement of MPI phenomena. It is written by pioneers as well as young leading scientists, and reviews both experimental findings and theoretical developments, discussing also the remaining open issues.

  9. On the angular distribution of spectator nucleons in high-energy collisions with deuterium nuclei

    International Nuclear Information System (INIS)

    Bartke, J.

    1975-01-01

    Angular distributions of spectator nucleons in collisions of high-energy particles with deuterium nuclei are discussed in the framework of the impulse model. Comparison with experimental data shows that predictions following from this simple theoretical model are verified by experiment. Some general remarks on the study of angular distributions of spectator nucleons are given. (author)

  10. Off-energy-shell variations of two-nucleon transition matrix and three-nucleon problem

    International Nuclear Information System (INIS)

    Stingl, M.; Sauer, P.U.

    1975-01-01

    For a schematic three-nucleon problem, approximate analytic expressions are derived for the functional derivatives of measurable three-particle quantities with respect to off-shell variations of the triplet-s two-nucleon transition matrix. Those quantities include neutron-deuteron scattering lengths, trinucleon binding energies, and the 3 He charge form-factor minimum; correlations between off-shell changes in the latter two are discussed. An indication is given how results of this kind may be to decide whether or not a given set of discrepancies between calculated and experimental three-nucleon observables can be reconciled in terms of off-shell variations of a nonretarded hermitean two-nucleon interaction. The treatment is not restricted to special classes of phase-shift equivalent potentials or phase-shift preserving transformations but instead makes use of a systematic parameterization of off-shell variations in terms of symmetric rational approximants of increasing order

  11. Electromagnetic interactions with nuclei and nucleons

    International Nuclear Information System (INIS)

    Thornton, S.T.; Sealock, R.M.

    1990-01-01

    This report discusses the following topics: general LEGS work; photodisintegration of the deuteron; progress towards other experiments; LEGS instrumentation; major LEGS software projects; NaI detector system; nucleon detector system; waveshifting fibers; EGN prototype detector for CEBAF; photon beam facility at CEBAF; delta electroproduction in nuclei; quasielastic scattering and excitation of the Delta by 4 He(e,e'); and quasielastic scattering at high Q 2

  12. 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.

  13. All the states of the nucleon. Nucleon spectroscopy through the production of mesons; Le nucleon dans tous ses etats. Etude de la spectroscopie du nucleon via la photoproduction de mesons

    Energy Technology Data Exchange (ETDEWEB)

    Rebreyend, D

    2006-10-15

    The photoproduction of mesons on the nucleon gives a direct access to its spectroscopy and is a promising way for the study of the structure of the nucleon. The GRAAL experiment uses a tagged and polarized photon beam produced through the Compton diffusion of laser photons on the electrons circulating in the ESRF storage ring. The combination of this photon beam and an efficient detection system has allowed a series of measurements concerning the photoproduction of light mesons on the proton and on the neutron. The first 4 chapters are dedicated to the nucleon spectroscopy: the nucleon models and their consequences on the excited levels are recalled, the experimental technique used is described and the difficulties due to the extraction of relevant data are presented. Highly accurate measurements of cross-sections, {sigma} asymmetry beams and resonance parameters have been performed. The last part is dedicated to the principle of the measurement of the electric dipole momentum of the neutron. (A.C.)

  14. Collective multipole excitations based on correlated realistic nucleon-nucleon interactions

    International Nuclear Information System (INIS)

    Paar, N.; Papakonstantinou, P.; Hergert, H.; Roth, R.

    2006-01-01

    We investigate collective multipole excitations for closed shell nuclei from 16 O to 208 Pb using correlated realistic nucleon-nucleon interactions in the framework of the random phase approximation (RPA). The dominant short-range central and tensor correlations a re treated explicitly within the Unitary Correlation Operator Method (UCOM), which provides a phase-shift equivalent correlated interaction VUCOM adapted to simple uncorrelated Hilbert spaces. The same unitary transformation that defines the correlated interaction is used to derive correlated transition operators. Using VUCOM we solve the Hartree-Fock problem and employ the single-particle states as starting point for the RPA. By construction, the UCOM-RPA is fully self-consistent, i.e. the same correlated nucleon-nucleon interact ion is used in calculations of the HF ground state and in the residual RPA interaction. Consequently, the spurious state associated with the center-of-mass motion is properly removed and the sum-rules are exhausted within ±3%. The UCOM-RPA scheme results in a collective character of giant monopole, dipole, and quadrupole resonances in closed-shell nuclei across the nuclear chart. For the isoscalar giant monopole resonance, the resonance energies are in agreement with experiment hinting at a reasonable compressibility. However, in the 1 - and 2 + channels the resonance energies are overestimated due to missing long-range correlations and three-body contributions. (orig.)

  15. Use of a finite range nucleon-nucleon interaction in the continuum shell model

    International Nuclear Information System (INIS)

    Faes, Jean-Baptiste

    2007-01-01

    The unification of nuclear structure and nuclear reactions was always a great challenge of nuclear physics. The extreme complexity of finite quantum systems lead in the past to a separate development of the nuclear structure and the nuclear reactions. A unified description of structure and reactions is possible within the continuum shell model. All previous applications of this model used the zero-range residual interaction and the finite depth local potential to generate the single-particle basis. In the thesis, we have presented an extension of the continuum shell model for finite-range nucleon-nucleon interaction and an arbitrary number of nucleons in the scattering continuum. The great advantage of the present formulation is the same two-body interaction used both to generate the single-particle basis and to describe couplings to the continuum states. This formulation opens a possibility for an ab initio continuum shell model studies with the same nucleon-nucleon interaction generating the nuclear mean field, the configuration mixing and the coupling to the scattering continuum. First realistic applications of the above model has been shown for spectra of "1"7F and "1"7O, and elastic phase-shifts in the reaction "1"6O(p, p)"1"6O. (author)

  16. Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons

    Directory of Open Access Journals (Sweden)

    Howell C.R.

    2016-01-01

    Full Text Available The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.

  17. On single nucleon wave functions in nuclei

    International Nuclear Information System (INIS)

    Talmi, Igal

    2011-01-01

    The strong and singular interaction between nucleons, makes the nuclear many body theory very complicated. Still, nuclei exhibit simple and regular features which are simply described by the shell model. Wave functions of individual nucleons may be considered just as model wave functions which bear little resemblance to the real ones. There is, however, experimental evidence for the reality of single nucleon wave functions. There is a simple method of constructing such wave functions for valence nucleons. It is shown that this method can be improved by considering the polarization of the core by the valence nucleon. This gives rise to some rearrangement energy which affects the single valence nucleon energy within the nucleus.

  18. Coloured quarks and the short range nucleon nucleon interaction

    International Nuclear Information System (INIS)

    Ribeiro, J.E.F.T.

    1978-02-01

    The strong repulsive core that exists in the scattering of two nucleons is studied with the help of the Resonating Group Method (R.G.M.), where the Pauli Principle of fermion antisymmetry is taken explicitly into account. The quark-quark potential is described in terms of colour (long range confining potential) and hyperfine interactions alone. The mass differences N*(1688) - N(938) and Δ(1236) = N(938) are used to fit the two free constants of the assumed quark potential. It is shown that although the Pauli Principle does not exclude ab initio a S state of two nucleons, a strong repulsive potential is, nevertheless, found. Two cases are studied in detail: The Isosinglet case (neutron proton scattering) and the Isotriplet one (identical nucleons). Phase shifts for each case are presented and the obtained relative wave functions are found consistent with the observed experimental features for the repulsive potential. Some formal results concerning an important class of operators characteristic of the present R.G.M. calculations are also presented. (author)

  19. Experimental tests of charge symmetry violation in parton distributions

    International Nuclear Information System (INIS)

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

    2005-01-01

    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

  20. Nuclear forces with Δ excitations up to next-to-next-to-leading order. Part I: Peripheral nucleon-nucleon waves

    International Nuclear Information System (INIS)

    Krebs, H.; Epelbaum, E.; Meissner, U.G.

    2007-01-01

    We study the two-nucleon force at next-to-next-to-leading order in a chiral effective field theory with explicit Δ degrees of freedom. Fixing the appearing low-energy constants from a next-to-leading-order calculation of pion-nucleon threshold parameters, we find an improved convergence of most peripheral nucleon-nucleon phases compared to the theory with pions and nucleons only. In the delta-full theory, the next-to-leading-order corrections are dominant in most partial waves considered. (orig.)

  1. Nucleon-nucleon interactions via Lattice QCD: Methodology. HAL QCD approach to extract hadronic interactions in lattice QCD

    Science.gov (United States)

    Aoki, Sinya

    2013-07-01

    We review the potential method in lattice QCD, which has recently been proposed to extract nucleon-nucleon interactions via numerical simulations. We focus on the methodology of this approach by emphasizing the strategy of the potential method, the theoretical foundation behind it, and special numerical techniques. We compare the potential method with the standard finite volume method in lattice QCD, in order to make pros and cons of the approach clear. We also present several numerical results for nucleon-nucleon potentials.

  2. Measurement of hard double-parton interactions in $W(\\to l\

    CERN Document Server

    Aad, Georges; Abbott, Brad; Abdallah, Jalal; Abdel Khalek, Samah; Abdelalim, Ahmed Ali; Abdinov, Ovsat; Aben, Rosemarie; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Ochoa, Ines; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Agustoni, Marco; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Allbrooke, Benedict; Allison, Lee John; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alonso, Francisco; Altheimer, Andrew David; Alvarez Gonzalez, Barbara; 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Auerbach, Benjamin; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Axen, David; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Backus Mayes, John; Badescu, Elisabeta; Bagnaia, Paolo; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Sarah; Balek, Petr; Balli, Fabrice; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Basye, Austin; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beale, Steven; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Sebastian; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Beemster, Lars; Begel, Michael; Behar Harpaz, Silvia; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Bertella, Claudia; Bertin, Antonio; Bertolucci, Federico; Besana, Maria Ilaria; Besjes, Geert-Jan; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianchini, Louis; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bittner, Bernhard; Black, Curtis; Black, James; Black, Kevin; Blair, Robert; Blanchard, Jean-Baptiste; Blazek, Tomas; Bloch, Ingo; Blocker, Craig; Blocki, Jacek; Blum, Walter; Blumenschein, Ulrike; Bobbink, Gerjan; Bobrovnikov, Victor; Bocchetta, Simona Serena; Bocci, Andrea; Boddy, Christopher Richard; Boehler, Michael; Boek, Jennifer; Boek, Thorsten Tobias; Boelaert, Nele; Bogaerts, Joannes Andreas; Bogdanchikov, Alexander; Bogouch, Andrei; Bohm, Christian; Bohm, Jan; Boisvert, Veronique; Bold, Tomasz; Boldea, Venera; Bolnet, Nayanka Myriam; 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Cuthbert, Cameron; Cwetanski, Peter; Czirr, Hendrik; Czodrowski, Patrick; Czyczula, Zofia; D'Auria, Saverio; D'Onofrio, Monica; D'Orazio, Alessia; Da Cunha Sargedas De Sousa, Mario Jose; Da Via, Cinzia; Dabrowski, Wladyslaw; Dafinca, Alexandru; Dai, Tiesheng; Dallaire, Frederick; Dallapiccola, Carlo; Dam, Mogens; Damiani, Daniel; Danielsson, Hans Olof; Dao, Valerio; Darbo, Giovanni; Darlea, Georgiana Lavinia; Dassoulas, James; Davey, Will; Davidek, Tomas; Davidson, Nadia; Davidson, Ruth; Davies, Eleanor; Davies, Merlin; Davignon, Olivier; Davison, Adam; Davygora, Yuriy; Dawe, Edmund; Dawson, Ian; Daya-Ishmukhametova, Rozmin; De, Kaushik; de Asmundis, Riccardo; De Castro, Stefano; De Cecco, Sandro; de Graat, Julien; De Groot, Nicolo; de Jong, Paul; De La Taille, Christophe; De la Torre, Hector; De Lorenzi, Francesco; De Nooij, Lucie; De Pedis, Daniele; De Salvo, Alessandro; De Sanctis, Umberto; De Santo, Antonella; De Vivie De Regie, Jean-Baptiste; De Zorzi, Guido; Dearnaley, William James; 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Guillemin, Thibault; Guindon, Stefan; Gul, Umar; Gunther, Jaroslav; Guo, Bin; Guo, Jun; Gutierrez, Phillip; Guttman, Nir; Gutzwiller, Olivier; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haas, Stefan; Haber, Carl; Hadavand, Haleh Khani; Hadley, David; Haefner, Petra; Hajduk, Zbigniew; Hakobyan, Hrachya; Hall, David; Halladjian, Garabed; Hamacher, Klaus; Hamal, Petr; Hamano, Kenji; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Handel, Carsten; Hanke, Paul; Hansen, John Renner; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hansson, Per; Hara, Kazuhiko; Harenberg, Torsten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Hartert, Jochen; Hartjes, Fred; Haruyama, Tomiyoshi; Harvey, Alex; Hasegawa, Satoshi; Hasegawa, Yoji; Hassani, Samira; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hayakawa, Takashi; Hayashi, Takayasu; Hayden, Daniel; Hays, Chris; Hayward, Helen; Haywood, Stephen; Head, Simon; Heck, Tobias; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heinemann, Beate; Heisterkamp, Simon; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, Robert; Henke, Michael; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Hensel, Carsten; Medina Hernandez, Carlos; Hernández Jiménez, Yesenia; Herrberg, Ruth; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Hickling, Robert; Higón-Rodriguez, Emilio; Hill, John; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirsch, Florian; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hohlfeld, Marc; Holmgren, Sven-Olof; Holy, Tomas; Holzbauer, Jenny; Hong, Tae Min; Hooft van Huysduynen, Loek; Horner, Stephan; Hostachy, Jean-Yves; Hou, Suen; Hoummada, Abdeslam; Howard, Jacob; Howarth, James; Hrabovsky, Miroslav; Hristova, Ivana; Hrivnac, Julius; Hryn'ova, Tetiana; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Hu, Diedi; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Hülsing, Tobias Alexander; Huettmann, Antje; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Huhtinen, Mika; Hurwitz, Martina; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibbotson, Michael; Ibragimov, Iskander; Iconomidou-Fayard, Lydia; Idarraga, John; Iengo, Paolo; Igonkina, Olga; Ikegami, Yoichi; Ikematsu, Katsumasa; Ikeno, Masahiro; Iliadis, Dimitrios; Ilic, Nikolina; Ince, Tayfun; Ioannou, Pavlos; Iodice, Mauro; Iordanidou, Kalliopi; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishino, Masaya; Ishitsuka, Masaki; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Ivashin, Anton; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, John; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakoubek, Tomas; Jakubek, Jan; Jamin, David Olivier; Jana, Dilip; Jansen, Eric; Jansen, Hendrik; Janssen, Jens; Jantsch, Andreas; Janus, Michel; Jared, Richard; Jarlskog, Göran; Jeanty, Laura; Jen-La Plante, Imai; Jeng, Geng-yuan; Jennens, David; Jenni, Peter; Loevschall-Jensen, Ask Emil; Jež, Pavel; Jézéquel, Stéphane; Jha, Manoj Kumar; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Shan; Jinnouchi, Osamu; Joergensen, Morten Dam; Joffe, David; Johansen, Marianne; Johansson, Erik; Johansson, Per; Johnert, Sebastian; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tim; Joram, Christian; Jorge, Pedro; Joshi, Kiran Daniel; Jovicevic, Jelena; Jovin, Tatjana; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Juranek, Vojtech; Jussel, Patrick; Juste Rozas, Aurelio; Kabana, Sonja; Kaci, Mohammed; Kaczmarska, Anna; Kadlecik, Peter; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kajomovitz, Enrique; Kalinin, Sergey; Kalinovskaya, Lidia; Kama, Sami; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kanno, Takayuki; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kar, Deepak; Karagounis, Michael; Karakostas, Konstantinos; Karnevskiy, Mikhail; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Yousuke; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kazama, Shingo; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Keener, Paul; Kehoe, Robert; Keil, Markus; Keller, John; Kenyon, Mike; Keoshkerian, Houry; Kepka, Oldrich; Kerschen, Nicolas; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Kharchenko, Dmitri; Khodinov, Alexander; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hyeon Jin; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; Kirk, Julie; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kitamura, Takumi; Kittelmann, Thomas; Kiuchi, Kenji; Kladiva, Eduard; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klemetti, Miika; Klier, Amit; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klinkby, Esben; Klioutchnikova, Tatiana; Klok, Peter; Klous, Sander; Kluge, Eike-Erik; Kluge, Thomas; Kluit, Peter; Kluth, Stefan; Kneringer, Emmerich; Knoops, Edith; Knue, Andrea; Ko, Byeong Rok; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Köneke, Karsten; König, Adriaan; Koenig, Sebastian; Köpke, Lutz; Koetsveld, Folkert; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohlmann, Simon; Kohn, Fabian; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kolanoski, Hermann; Kolesnikov, Vladimir; Koletsou, Iro; Koll, James; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kono, Takanori; Kononov, Anatoly; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kopeliansky, Revital; Koperny, Stefan; Kopp, Anna Katharina; Korcyl, Krzysztof; Kordas, Kostantinos; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotov, Sergey; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, Jana; Krauss, Frank; Kravchenko, Anton; Kreiss, Sven; Krejci, Frantisek; Kretzschmar, Jan; Kreutzfeldt, Kristof; Krieger, Nina; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruse, Mark; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Thorsten; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kuna, Marine; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurata, Masakazu; Kurochkin, Yurii; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; Kwee, Regina; La Rosa, Alessandro; La Rotonda, Laura; Labarga, Luis; Lablak, Said; Lacasta, Carlos; Lacava, Francesco; Lacey, James; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laisne, Emmanuel; Lambourne, Luke; Lampen, Caleb; Lampl, Walter; Lancon, Eric; Landgraf, Ulrich; Landon, Murrough; Lang, Valerie Susanne; Lange, Clemens; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Lanza, Agostino; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Larner, Aimee; Lassnig, Mario; Laurelli, Paolo; Lavorini, Vincenzo; Lavrijsen, Wim; Laycock, Paul; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Menedeu, Eve; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Michel; Legendre, Marie; Legger, Federica; Leggett, Charles; Lehmacher, Marc; Lehmann Miotto, Giovanna; Leister, Andrew Gerard; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Lemmer, Boris; Lendermann, Victor; Leney, Katharine; Lenz, Tatiana; Lenzen, Georg; Lenzi, Bruno; Leonhardt, Kathrin; Leontsinis, Stefanos; Lepold, Florian; Leroy, Claude; Lessard, Jean-Raphael; Lester, Christopher; Lester, Christopher Michael; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bing; Li, Bo; Li, Haifeng; Li, Ho Ling; Li, Shu; Li, Xuefei; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lie, Ki; Liebig, Wolfgang; Limbach, Christian; Limosani, Antonio; Limper, Maaike; Lin, Simon; Linde, Frank; Linnemann, James; Lipeles, Elliot; Lipniacka, Anna; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Dong; Liu, Jianbei; Liu, Lulu; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Lombardo, Vincenzo Paolo; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lo Sterzo, Francesco; Losty, Michael; Lou, XinChou; Lounis, Abdenour; Loureiro, Karina; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Ludwig, Dörthe; Ludwig, Inga; Ludwig, Jens; Luehring, Frederick; Lukas, Wolfgang; Luminari, Lamberto; Lund, Esben; Lund-Jensen, Bengt; Lundberg, Björn; Lundberg, Johan; Lundberg, Olof; Lundquist, Johan; Lungwitz, Matthias; Lynn, David; Lytken, Else; Ma, Hong; Ma, Lian Liang; Maccarrone, Giovanni; Macchiolo, Anna; Maček, Boštjan; Machado Miguens, Joana; Macina, Daniela; Mackeprang, Rasmus; Madar, Romain; Madaras, Ronald; Maddocks, Harvey Jonathan; Mader, Wolfgang; Madsen, Alexander Kondrup; Maeno, Mayuko; Maeno, Tadashi; Mättig, Peter; Mättig, Stefan; Magnoni, Luca; Magradze, Erekle; Mahboubi, Kambiz; Mahlstedt, Joern; Mahmoud, Sara; Mahout, Gilles; Maiani, Camilla; Maidantchik, Carmen; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Malecki, Piotr; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mamuzic, Judita; Manabe, Atsushi; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Manfredini, Alessandro; Manhaes de Andrade Filho, Luciano; Manjarres Ramos, Joany Andreina; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Mantifel, Rodger; Mapelli, Alessandro; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchese, Fabrizio; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marroquim, Fernando; Marshall, Zach; Marti, Lukas Fritz; Marti-Garcia, Salvador; Martin, Brian; Martin, Brian Thomas; Martin, Jean-Pierre; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martin-Haugh, Stewart; Martinez, Homero; Martinez, Mario; Martinez Outschoorn, Verena; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Matsunaga, Hiroyuki; Matsushita, Takashi; Mattravers, Carly; Maurer, Julien; Maxfield, Stephen; Maximov, Dmitriy; Mazini, Rachid; Mazur, Michael; Mazzaferro, Luca; Mazzanti, Marcello; Mc Donald, Jeffrey; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; Mchedlidze, Gvantsa; Mclaughlan, Tom; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Mechtel, Markus; Medinnis, Mike; Meehan, Samuel; Meera-Lebbai, Razzak; Meguro, Tatsuma; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meineck, Christian; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Meloni, Federico; Mendoza Navas, Luis; Meng, Zhaoxia; Mengarelli, Alberto; Menke, Sven; Meoni, Evelin; Mercurio, Kevin Michael; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Meyer, Joerg; Michal, Sebastien; Micu, Liliana; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Miller, David; Miller, Robert; Mills, Bill; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Milutinovic-Dumbelovic, Gordana; Minaenko, Andrey; Miñano Moya, Mercedes; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Mitrevski, Jovan; Mitsou, Vasiliki A; Mitsui, Shingo; Miyagawa, Paul; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Moeller, Victoria; Mönig, Klaus; Möser, Nicolas; Mohapatra, Soumya; Mohr, Wolfgang; Moles-Valls, Regina; Molfetas, Angelos; Monk, James; Monnier, Emmanuel; Montejo Berlingen, Javier; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Mora Herrera, Clemencia; Moraes, Arthur; Morange, Nicolas; Morel, Julien; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Morley, Anthony Keith; Mornacchi, Giuseppe; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Mueller, Felix; Mueller, James; Mueller, Klemens; Müller, Thomas; Mueller, Timo; Muenstermann, Daniel; Munwes, Yonathan; Murray, Bill; Mussche, Ido; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nackenhorst, Olaf; Nadal, Jordi; Nagai, Koichi; Nagai, Ryo; Nagai, Yoshikazu; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Namasivayam, Harisankar; Nanava, Gizo; Napier, Austin; Narayan, Rohin; Nash, Michael; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Neal, Homer; Nechaeva, Polina; Neep, Thomas James; Negri, Andrea; Negri, Guido; Negrini, Matteo; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neumann, Manuel; Neusiedl, Andrea; Neves, Ricardo; Nevski, Pavel; Newcomer, Mitchel; Newman, Paul; Nguyen, Duong Hai; Nguyen Thi Hong, Van; Nickerson, Richard; Nicolaidou, Rosy; Nicquevert, Bertrand; Niedercorn, Francois; Nielsen, Jason; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsen, Henrik; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nisius, Richard; Nobe, Takuya; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Norberg, Scarlet; Nordberg, Markus; Novakova, Jana; Nozaki, Mitsuaki; Nozka, Libor; Nuncio-Quiroz, Adriana-Elizabeth; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; O'Brien, Brendan Joseph; O'Neil, Dugan; O'Shea, Val; Oakes, Louise Beth; Oakham, Gerald; Oberlack, Horst; Ocariz, Jose; Ochi, Atsuhiko; Oda, Susumu; Odaka, Shigeru; Odier, Jerome; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohshima, Takayoshi; Okamura, Wataru; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira, Miguel Alfonso; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olivito, Dominick; Olszewski, Andrzej; Olszowska, Jolanta; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlando, Nicola; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Osuna, Carlos; Otero y Garzon, Gustavo; Ottersbach, John; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Owen, Simon; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagan Griso, Simone; Paganis, Efstathios; Pahl, Christoph; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Paleari, Chiara; Palestini, Sandro; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panduro Vazquez, William; Pani, Priscilla; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Papadelis, Aras; Papadopoulou, Theodora; Paramonov, Alexander; Paredes Hernandez, Daniela; Park, Woochun; Parker, Michael Andrew; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pashapour, Shabnaz; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pearce, James; Pedersen, Maiken; Pedraza Lopez, Sebastian; Pedraza Morales, Maria Isabel; Peleganchuk, Sergey; Pelikan, Daniel; Peng, Haiping; Penning, Bjoern; Penson, Alexander; Penwell, John; Perez Cavalcanti, Tiago; Perez Codina, Estel; Pérez García-Estañ, María Teresa; Perez Reale, Valeria; Perini, Laura; Pernegger, Heinz; Perrino, Roberto; Perrodo, Pascal; Peshekhonov, Vladimir; Peters, Krisztian; Peters, Yvonne; Petersen, Brian; Petersen, Jorgen; Petersen, Troels; Petit, Elisabeth; Petridis, Andreas; Petridou, Chariclia; Petrolo, Emilio; Petrucci, Fabrizio; Petschull, Dennis; Petteni, Michele; Pezoa, Raquel; Phan, Anna; Phillips, Peter William; Piacquadio, Giacinto; Picazio, Attilio; Piccaro, Elisa; Piccinini, Maurizio; Piec, Sebastian Marcin; Piegaia, Ricardo; Pignotti, David; Pilcher, James; Pilkington, Andrew; Pina, João Antonio; Pinamonti, Michele; Pinder, Alex; Pinfold, James; Pingel, Almut; Pinto, Belmiro; Pizio, Caterina; Pleier, Marc-Andre; Pleskot, Vojtech; Plotnikova, Elena; Plucinski, Pawel; Poblaguev, Andrei; Poddar, Sahill; Podlyski, Fabrice; Poettgen, Ruth; Poggioli, Luc; Pohl, David-leon; Pohl, Martin; Polesello, Giacomo; Policicchio, Antonio; Polifka, Richard; Polini, Alessandro; Poll, James; Polychronakos, Venetios; Pomeroy, Daniel; Pommès, Kathy; Pontecorvo, Ludovico; Pope, Bernard; Popeneciu, Gabriel Alexandru; Popovic, Dragan; Poppleton, Alan; Portell Bueso, Xavier; Pospelov, Guennady; Pospisil, Stanislav; Potrap, Igor; Potter, Christina; Potter, Christopher; Poulard, Gilbert; Poveda, Joaquin; Pozdnyakov, Valery; Prabhu, Robindra; Pralavorio, Pascal; Pranko, Aliaksandr; Prasad, Srivas; Pravahan, Rishiraj; Prell, Soeren; Pretzl, Klaus Peter; Price, Darren; Price, Joe; Price, Lawrence; Prieur, Damien; Primavera, Margherita; Proissl, Manuel; Prokofiev, Kirill; Prokoshin, Fedor; Protopopescu, Serban; Proudfoot, James; Prudent, Xavier; Przybycien, Mariusz; Przysiezniak, Helenka; Psoroulas, Serena; Ptacek, Elizabeth; Pueschel, Elisa; Puldon, David; Purohit, Milind; Puzo, Patrick; Pylypchenko, Yuriy; Qian, Jianming; Quadt, Arnulf; Quarrie, David; Quayle, William; Raas, Marcel; Radeka, Veljko; Radescu, Voica; Radloff, Peter; Ragusa, Francesco; Rahal, Ghita; Rahimi, Amir; Rajagopalan, Srinivasan; Rammensee, Michael; Rammes, Marcus; Randle-Conde, Aidan Sean; Randrianarivony, Koloina; Rangel-Smith, Camila; Rao, Kanury; Rauscher, Felix; Rave, Tobias Christian; Raymond, Michel; Read, Alexander Lincoln; Rebuzzi, Daniela; Redelbach, Andreas; Redlinger, George; Reece, Ryan; Reeves, Kendall; Reinsch, Andreas; Reisinger, Ingo; Relich, Matthew; Rembser, Christoph; Ren, Zhongliang; Renaud, Adrien; Rescigno, Marco; Resconi, Silvia; Resende, Bernardo; Reznicek, Pavel; Rezvani, Reyhaneh; Richter, Robert; Richter-Was, Elzbieta; Ridel, Melissa; Rieck, Patrick; Rijssenbeek, Michael; Rimoldi, Adele; Rinaldi, Lorenzo; Rios, Ryan Randy; Ritsch, Elmar; Riu, Imma; Rivoltella, Giancesare; Rizatdinova, Flera; Rizvi, Eram; Robertson, Steven; Robichaud-Veronneau, Andree; Robinson, Dave; Robinson, James; Robson, Aidan; Rocha de Lima, Jose Guilherme; Roda, Chiara; Roda Dos Santos, Denis; Roe, Adam; Roe, Shaun; Røhne, Ole; Rolli, Simona; Romaniouk, Anatoli; Romano, Marino; Romeo, Gaston; Romero Adam, Elena; Rompotis, Nikolaos; Roos, Lydia; Ros, Eduardo; Rosati, Stefano; Rosbach, Kilian; Rose, Anthony; Rose, Matthew; Rosenbaum, Gabriel; Rosendahl, Peter Lundgaard; Rosenthal, Oliver; Rosselet, Laurent; Rossetti, Valerio; Rossi, Elvira; Rossi, Leonardo Paolo; Rotaru, Marina; Roth, Itamar; Rothberg, Joseph; Rousseau, David; Royon, Christophe; Rozanov, Alexandre; Rozen, Yoram; Ruan, Xifeng; Rubbo, Francesco; Rubinskiy, Igor; Ruckstuhl, Nicole; Rud, Viacheslav; Rudolph, Christian; Rudolph, Matthew Scott; Rühr, Frederik; Ruiz-Martinez, Aranzazu; Rumyantsev, Leonid; Rurikova, Zuzana; Rusakovich, Nikolai; Ruschke, Alexander; Rutherfoord, John; Ruthmann, Nils; Ruzicka, Pavel; Ryabov, Yury; 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True, Patrick; Trzebinski, Maciej; Trzupek, Adam; Tsarouchas, Charilaos; Tseng, Jeffrey; Tsiakiris, Menelaos; Tsiareshka, Pavel; Tsionou, Dimitra; Tsipolitis, Georgios; Tsiskaridze, Shota; Tsiskaridze, Vakhtang; Tskhadadze, Edisher; Tsukerman, Ilya; Tsulaia, Vakhtang; Tsung, Jieh-Wen; Tsuno, Soshi; Tsybychev, Dmitri; Tua, Alan; Tudorache, Alexandra; Tudorache, Valentina; Tuggle, Joseph; Turala, Michal; Turecek, Daniel; Turk Cakir, Ilkay; Turra, Ruggero; Tuts, Michael; Tykhonov, Andrii; Tylmad, Maja; Tyndel, Mike; Tzanakos, George; Uchida, Kirika; Ueda, Ikuo; Ueno, Ryuichi; Ughetto, Michael; Ugland, Maren; Uhlenbrock, Mathias; Ukegawa, Fumihiko; Unal, Guillaume; Undrus, Alexander; Unel, Gokhan; Ungaro, Francesca; Unno, Yoshinobu; Urbaniec, Dustin; Urquijo, Phillip; Usai, Giulio; Vacavant, Laurent; Vacek, Vaclav; Vachon, Brigitte; Vahsen, Sven; Valencic, Nika; Valentinetti, Sara; Valero, Alberto; Valery, Loic; Valkar, Stefan; Valladolid Gallego, Eva; Vallecorsa, Sofia; Valls Ferrer, Juan Antonio; 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Vlachos, Sotirios; Vladoiu, Dan; Vlasak, Michal; Vogel, Adrian; Vokac, Petr; Volpi, Guido; Volpi, Matteo; Volpini, Giovanni; von der Schmitt, Hans; von Radziewski, Holger; von Toerne, Eckhard; Vorobel, Vit; Vorwerk, Volker; Vos, Marcel; Voss, Rudiger; Vossebeld, Joost; Vranjes, Nenad; Vranjes Milosavljevic, Marija; Vrba, Vaclav; Vreeswijk, Marcel; Vu Anh, Tuan; Vuillermet, Raphael; Vukotic, Ilija; Vykydal, Zdenek; Wagner, Wolfgang; Wagner, Peter; Wahlen, Helmut; Wahrmund, Sebastian; Wakabayashi, Jun; Walch, Shannon; Walder, James; Walker, Rodney; Walkowiak, Wolfgang; Wall, Richard; Waller, Peter; Walsh, Brian; Wang, Chiho; Wang, Haichen; Wang, Hulin; Wang, Jike; Wang, Jin; Wang, Kuhan; Wang, Rui; Wang, Song-Ming; Wang, Tan; Wang, Xiaoxiao; Warburton, Andreas; Ward, Patricia; Wardrope, David Robert; Warsinsky, Markus; Washbrook, Andrew; Wasicki, Christoph; Watanabe, Ippei; Watkins, Peter; Watson, Alan; Watson, Ian; Watson, Miriam; Watts, Gordon; Watts, Stephen; Waugh, Anthony; Waugh, Ben; 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Zanello, Lucia; Zanzi, Daniele; Zaytsev, Alexander; Zeitnitz, Christian; Zeman, Martin; Zemla, Andrzej; Zenin, Oleg; Ženiš, Tibor; Zinonos, Zinonas; Zerwas, Dirk; Zevi della Porta, Giovanni; Zhang, Dongliang; Zhang, Huaqiao; Zhang, Jinlong; Zhang, Lei; Zhang, Xueyao; Zhang, Zhiqing; Zhao, Long; Zhao, Zhengguo; Zhemchugov, Alexey; Zhong, Jiahang; Zhou, Bing; Zhou, Ning; Zhou, Yue; Zhu, Cheng Guang; Zhu, Hongbo; Zhu, Junjie; Zhu, Yingchun; Zhuang, Xuai; Zhuravlov, Vadym; Zibell, Andre; Zieminska, Daria; Zimin, Nikolai; Zimmermann, Robert; Zimmermann, Simone; Zimmermann, Stephanie; Ziolkowski, Michael; Zitoun, Robert; Živković, Lidija; Zmouchko, Viatcheslav; Zobernig, Georg; Zoccoli, Antonio; zur Nedden, Martin; Zutshi, Vishnu; Zwalinski, Lukasz

    2013-03-25

    The production of W bosons in association with two jets in proton-proton collisions at a centre-of-mass energy of $\\sqrt{s}$=7 TeV has been analysed for the presence of double-parton interactions using data corresponding to an integrated luminosity of 36/pb, collected with the ATLAS detector at the LHC. The fraction of events arising from double-parton interactions, $f_{DP}^{(D)}$ has been measured through the momentum balance between the two jets and amounts to $f_{DP}^{(D)} = 0.08 \\pm 0.01 (stat.) \\pm 0.02 (sys.)$ for jets with transverse momentum PT > 20 GeV and rapidity |y|<2.8. This corresponds to a measurement of the effective area parameter for hard double-parton interactions of $\\sigma_{eff} = 15 \\pm 3 (stat.)^{+5}_{-3}$ (sys.) mb.

  3. QCD's Partner Needed for Mass Spectra and Parton Structure Functions

    International Nuclear Information System (INIS)

    Kim, Y.S.

    2009-01-01

    as in the case of the hydrogen atom, bound-state wave functions are needed to generate hadronic spectra. For this purpose, in 1971, Feynman and his students wrote down a Lorentz-invariant harmonic oscillator equation. This differential equation has one set of solutions satisfying the Lorentz-covariant boundary condition. This covariant set generates Lorentz-invariant mass spectra with their degeneracies. Furthermore, the Lorentz-covariant wave functions allow us to calculate the valence parton distribution by Lorentz-boosting the quark-model wave function from the hadronic rest frame. However, this boosted wave function does not give an accurate parton distribution. The wave function needs QCD corrections to make a contact with the real world. Likewise, QCD needs the wave function as a starting point for calculating the parton structure function. (author)

  4. Dual model for parton densities

    International Nuclear Information System (INIS)

    El Hassouni, A.; Napoly, O.

    1981-01-01

    We derive power-counting rules for quark densities near x=1 and x=0 from parton interpretations of one-particle inclusive dual amplitudes. Using these rules, we give explicit expressions for quark distributions (including charm) inside hadrons. We can then show the compatibility between fragmentation and recombination descriptions of low-p/sub perpendicular/ processes

  5. Unveiling the nucleon tensor charge at Jefferson Lab: A study of the SoLID case

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Zhihong; Sato, Nobuo; Allada, Kalyan; Liu, Tianbo; Chen, Jian-Ping; Gao, Haiyan; Kang, Zhong-Bo; Prokudin, Alexei; Sun, Peng; Yuan, Feng

    2017-04-01

    © 2017 The Authors Future experiments at the Jefferson Lab 12 GeV upgrade, in particular, the Solenoidal Large Intensity Device (SoLID), aim at a very precise data set in the region where the partonic structure of the nucleon is dominated by the valence quarks. One of the main goals is to constrain the quark transversity distributions. We apply recent theoretical advances of the global QCD extraction of the transversity distributions to study the impact of future experimental data from the SoLID experiments. Especially, we develop a simple strategy based on the Hessian matrix analysis that allows one to estimate the uncertainties of the transversity quark distributions and their tensor charges extracted from SoLID data simulation. We find that the SoLID measurements with the proton and the effective neutron targets can improve the precision of the u- and d-quark transversity distributions up to one order of magnitude in the range 0.05 < x < 0.6.

  6. Warming up a nucleon

    International Nuclear Information System (INIS)

    Eletsky, V.L.

    1991-01-01

    The problem of temperature dependence of nucleon mass is addressed by considering a retarded correlator of two currents with quantum numbers of a nucleon at finite temperature T π in the chiral limit. It is shown that at Euclidean momenta the leading one-loop corrections arise from direct interaction of thermal pions with the currents. A dispersive representation for the correlator shows that this interaction smears the nucleon pole over frequency interval with width ∼ T. This interaction does not change the exponential fall-off of the correlator in Euclidean space but gives an O(T 2 /F π 2 ) contribution to the pre-exponential factor. 11 refs. (author)

  7. Nucleon-nucleon interaction in the soliton bag model

    International Nuclear Information System (INIS)

    Schuh, A.

    1985-01-01

    In the framework of the Soliton Bag Model introduced by Friedberg and Lee we treat S-wave nucleon-nucleon scattering. Our system consists of six quarks and the nontopological soliton field which represents an average colorfree interaction between the quarks and yields their (relative) confinement. The dynamical problem is treated by means of the Generator coordinate Method (GCM) where the total wave function is the weighted sum over static configurations of prescribed bag deformation. The static configurations needed for the GCM ansatz are generated starting from a potential well of prescribed deformation wherein we solve the Dirac equation for the quarks. The single particle quark orbitals are properly coupled with respect to orbital, color, spin, and isospin quantum numbers to form a totally antisymmetric 6-quark state. A mean field solution for the soliton field is then calculated and turned into a quantum mechanical state by a coherent state approximation. Since these static configurations are only to be seen as wave function generators for the GCM no selfconsistency between quark and soliton solution is enforced. With these configurations we then evaluate the norm and Hamiltonian kernels appearing in the GCM treatment. The Hill-Wheeler integral equation for the weight functions is transformed into a Schroedinger-type differential equation by an expansion into symmetric moments of up to second order. This equation is brought into a form where we can identify the interaction potential unambiguously. We find an intermediate range attraction of about 120 MeV and no attraction in the vicinity of the spherically symmetric shape of the system, in contradiction to the naive adiabatic potentials widely used in quark models for the nucleon-nucleon interaction up to now. (orig./HSI) [de

  8. VNI version 4.1. Simulation of high-energy particle collisions in QCD: Space-time evolution of e+e-... A + B collisions with parton-cascades, cluster-hadronization, final-state hadron cascades

    International Nuclear Information System (INIS)

    Geiger, K.; Longacre, R.

    1999-01-01

    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 treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. Finally, the cascading of produced prehadronic clusters and of hadrons includes a multitude of 2 → n processes, and is modeled in parallel to the parton cascade description. This paper gives a brief review of the physics underlying VNI, as well as a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including simple examples), annotates input and control parameters, and discusses output data provided by it

  9. Few-nucleon systems (theory)

    International Nuclear Information System (INIS)

    Schwamb, M.

    2006-01-01

    An overview over present achievements and future challenges in the field of few-nucleon systems is presented. Special emphasis is laid on the construction of a unified approach to hadronic and electromagnetic reactions on few-nucleon systems, necessary for studying the borderline between quark-gluon and effective descriptions. (orig.) (orig.)

  10. Polarized lepton-nucleon scattering

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, E. [Stanford Univ., CA (United States)

    1994-12-01

    The author provides a summary of the proposed and published statistical (systematic) uncertainties from the world experiments on nucleon spin structure function integrals. By the time these programs are complete, there will be a vast resource of data on nucleon spin structure functions. Each program has quite different experimental approaches regarding the beams, targets, and spectrometers thus ensuring systematically independent tests of the spin structure function measurements. Since the field of spin structure function measurements began, there has been a result appearing approximately every five years. With advances in polarized target technology and high polarization in virtually all of the lepton beams, results are now coming out each year; this is a true signature of the growth in the field. Hopefully, the experiments will provide a consistent picture of nucleon spin structure at their completion. In summary, there are still many open questions regarding the internal spin structure of the nucleon. Tests of QCD via the investigation of the Bjorken sum rule is a prime motivator for the field, and will continue with the next round of precision experiments. The question of the origin of spin is still a fundamental problem. Researchers hope is that high-energy probes using spin will shed light on this intriguing mystery, in addition to characterizing the spin structure of the nucleon.

  11. Polarized lepton-nucleon scattering

    International Nuclear Information System (INIS)

    Hughes, E.

    1994-01-01

    The author provides a summary of the proposed and published statistical (systematic) uncertainties from the world experiments on nucleon spin structure function integrals. By the time these programs are complete, there will be a vast resource of data on nucleon spin structure functions. Each program has quite different experimental approaches regarding the beams, targets, and spectrometers thus ensuring systematically independent tests of the spin structure function measurements. Since the field of spin structure function measurements began, there has been a result appearing approximately every five years. With advances in polarized target technology and high polarization in virtually all of the lepton beams, results are now coming out each year; this is a true signature of the growth in the field. Hopefully, the experiments will provide a consistent picture of nucleon spin structure at their completion. In summary, there are still many open questions regarding the internal spin structure of the nucleon. Tests of QCD via the investigation of the Bjorken sum rule is a prime motivator for the field, and will continue with the next round of precision experiments. The question of the origin of spin is still a fundamental problem. Researchers hope is that high-energy probes using spin will shed light on this intriguing mystery, in addition to characterizing the spin structure of the nucleon

  12. Hadronic top-quark pair-production with one jet and parton showering

    Energy Technology Data Exchange (ETDEWEB)

    Alioli, Simone; Moch, Sven-Olaf [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Uwer, Peter [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2011-10-15

    We present a calculation of heavy-flavor production in hadronic collisions in association with one jet matched to parton shower Monte Carlo programs at next-to-leading order in perturbative QCD. Top-quark decays are included and spin correlations in the decay products are taken into account. The calculation builds on existing results for the radiative corrections to heavy-quark plus one jet production and uses the POWHEG BOX for the interface to the parton shower programs PYTHIA or HERWIG. A broad phenomenological study for the Large Hadron Collider and the Tevatron is presented. In particular we study - as one important sample application - the impact of the parton shower on the top-quark charge asymmetry. (orig.)

  13. Hadronization of dense partonic matter

    Energy Technology Data Exchange (ETDEWEB)

    Fries, Rainer J [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2006-12-15

    The parton recombination model has turned out to be a valuable tool to describe hadronization in high-energy heavy-ion collisions. I review the model and revisit recent progress in our understanding of hadron correlations. I also discuss higher Fock states in the hadrons, possible violations of the elliptic flow scaling and recombination effects in more dilute systems.

  14. New QCD sum rules for nucleon axial-vector coupling constants

    International Nuclear Information System (INIS)

    Lee, F.X.; Leinweber, D.B.; Jin, X.

    1997-01-01

    Two new sets of QCD sum rules for the nucleon axial-vector coupling constants are derived using the external-field technique and generalized interpolating fields. An in-depth study of the predicative ability of these sum rules is carried out using a Monte Carlo based uncertainty analysis. The results show that the standard implementation of the QCD sum rule method has only marginal predicative power for the nucleon axial-vector coupling constants, as the relative errors are large. The errors range from approximately 50% to 100% compared to the nucleon mass obtained from the same method, which has only a 10%- 25% error. The origin of the large errors is examined. Previous analyses of these coupling constants are based on sum rules that have poor operator product expansion convergence and large continuum contributions. Preferred sum rules are identified and their predictions are obtained. We also investigate the new sum rules with an alternative treatment of the problematic transitions which are not exponentially suppressed in the standard treatment. The alternative treatment provides exponential suppression of their contributions relative to the ground state. Implications for other nucleon current matrix elements are also discussed. copyright 1997 The American Physical Society

  15. Experimental determination of the effective nucleon-nucleon interaction for p-nucleus reactions at intermediate energies

    International Nuclear Information System (INIS)

    McClelland, J.B.; Aas, B.; Azizi, A.

    1982-01-01

    A complete measurement of the polarization transfer observables has been made for the first time in the (p,p') reaction at intermediate energies. Measurements are reported for the 12 C(p,p') 12 C reaction to the 1 + , T = 0(12.71 MeV) and 1 + , T = 1(15.11 MeV) states at 500 MeV at laboratory scattering angles of 3.5 0 , 5.5 0 , 7.5 0 , and 12.0 0 . Linear combinations of these observables are shown to exhibit a very selective dependence on the isoscalar and isovector spin-dependent components of the nucleon-nucleon interaction. To the extent of the validity of the single collision approximation, these amplitudes are compared directly to the free nucleon-nucleon amplitudes at small momentum transfers

  16. Electromagnetic structure of a bound nucleon

    International Nuclear Information System (INIS)

    Nogami, Y.

    1977-01-01

    The effect of binding on the electromagnetic (e.m.) structure of a nucleon in a nucleus is examined by means of a model consisting of a single nucleon which is bound in a harmonic oscillator potential and also coupled to the pion field through the Chew-Low interaction. The 'two-pion contribution' to the e.m. structure is considered. This is the part which is probably most susceptible to the binding effect. By the binding effect it is meant the one which arises because the nucleon wave functions, in the intermediate state as well as in the initial and final states, are distorted by the potential in which the nucleon is bound. This may be compared to a similar correction to the impulse approximation for pion-nucleus scattering. Unlike the latter which is likely to be quite appreciable, the binding correction to the e.m. structure of the nucleon is found to be negligibly small. The so-called quenching effect due to the Pauli principle when there are other nucleons is also discussed [pt

  17. Three nucleon interaction and nuclear composition

    International Nuclear Information System (INIS)

    Pandharipande, V.R.

    1983-01-01

    The author discusses results of some of the calculations carried out by J. Carlson, I. Lagaris, J. Lomnitz-Adler, R.A. Smith, R.B. Wiringa and himself to study the three nucleon interaction. The group has attempted to calculate the wavefunctions and binding energies of 3 H, 3 He, 4 He and nuclear matter, with the variational method, from a nonrelativistic Hamiltonian. Only nucleon degrees of freedom are retained in this Hamiltonian; the effects of other degrees of freedom are implicit in the two and three nucleon potentials. The author discusses further the calculations carried out, in collaboration with B. Friman, and R.B. Wiringa, to study the composition of nuclei. Nucleons interact by many processes including exchange of pions with or without excitation to isobar (Δ) states. Thus the nucleus contains pions being exchanged, and some nucleons in the Δ state. The group attempts to calculate the number and momentum distribution of these exchanged pions, and the fraction of time a nucleon in the nucleus is in the Δ state. 21 references, 4 figures

  18. The study of nucleon-nucleon interaction from the 3 nucleon interaction D(n,nnp) at 14 MeV

    International Nuclear Information System (INIS)

    Gondrand, Jean-Claude

    1970-01-01

    The n-p spectrum for the neutron-proton final state interaction in a complete D(n,nnp) experiment at 14 MeV was measured with a two-dimensional time-of-flight spectrometer. A previously measured n-n spectrum, and the n-p spectrum are compared with theoretical convoluted spectra obtained from Faddeev equations (AMADO Model) for three nucleon-nucleon potentials. The cross-sections σ(E 1 ,Ω 1 ,Ω 2 ) are extracted from the two experimental spectra by a simulation method. (author) [fr

  19. Nucleon strangeness: present and future

    CERN Document Server

    Sapozhnikov, M G

    2010-01-01

    A review of experimental results for the measurement of the strange quark distributions in the nucleon, is given. Contributions of the strange quarks to the nucleon mass, electromagnetic form factors and spin, are discussed.

  20. Effective pion--nucleon interaction in nuclear matter

    International Nuclear Information System (INIS)

    Celenza, L.S.; Liu, L.C.; Nutt, W.; Shakin, C.M.

    1976-01-01

    We discuss the modification of the interaction between a pion and a nucleon in the presence of an infinite medium of nucleons (nuclear matter). The theory presented here is covariant and is relevant to the calculation of the pion--nucleus optical potential. The specific effects considered are the modifications of the nucleon propagator due to the Pauli principle and the modification of the pion and nucleon propagators due to collisions with nucleons of the medium. We also discuss in detail the pion self-energy in the medium, paying close attention to off-shell effects. These latter effects are particularly important because of the rapid variation with energy of the fundamental pion--nucleon interaction. Numerical results are presented, the main feature being the appearance of a significant damping width for the (3, 3) resonance

  1. QCD parton model at collider energies

    International Nuclear Information System (INIS)

    Ellis, R.K.

    1984-09-01

    Using the example of vector boson production, the application of the QCD improved parton model at collider energies is reviewed. The reliability of the extrapolation to SSC energies is assessed. Predictions at √S = 0.54 TeV are compared with data. 21 references

  2. Chemical and kinetic equilibrations via radiative parton transport

    International Nuclear Information System (INIS)

    Zhang Bin; Wortman, Warner A

    2011-01-01

    A hot and dense partonic system can be produced in the early stage of a relativistic heavy ion collision. How it equilibrates is important for the extraction of Quark-Gluon Plasma properties. We study the chemical and kinetic equilibrations of the Quark-Gluon Plasma using a radiative transport model. Thermal and Color-Glass-Condensate motivated initial conditions are used. We observe that screened parton interactions always lead to partial pressure isotropization. Different initial pressure anisotropies result in the same asymptotic evolution. Comparison of evolutions with and without radiative processes shows that chemical equilibration interacts with kinetic equilibration and radiative processes can contribute significantly to pressure isotropization.

  3. Mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter within the relativistic impulse approximation

    International Nuclear Information System (INIS)

    Jiang Weizhou; Li Baoan; Chen Liewen

    2007-01-01

    The mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter are investigated using the nucleon optical potential obtained within the relativistic impulse approximation with the empirical nucleon-nucleon scattering amplitudes and the nuclear densities obtained in the relativistic mean-field model. It is found that the isospin-splitting of nucleon mean free paths, sensitive to the imaginary part of the symmetry potential, changes its sign at certain high kinetic energy. The in-medium nucleon-nucleon cross sections are analytically and numerically demonstrated to be essentially independent of the isospin asymmetry of the medium and increase linearly with density in the high-energy region where the relativistic impulse approximation is applicable

  4. Testing partonic charge symmetry at a high-energy electron collider

    International Nuclear Information System (INIS)

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

    2011-01-01

    We examine the possibility that one could measure partonic charge symmetry violation (CSV) by comparing neutrino or antineutrino production through charged-current reactions induced by electrons or positrons at a possible electron collider at the LHC. We calculate the magnitude of CSV that might be expected at such a facility. We show that this is likely to be a several percent effect, substantially larger than the typical CSV effects expected for partonic reactions.

  5. Deeply Virtual Compton scattering at CERN. What is the size of the proton?

    Energy Technology Data Exchange (ETDEWEB)

    Joerg, Philipp

    2017-04-27

    Tremendous efforts have been made to understand the Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism, which led to the successful discovery of the Higgs Boson and the clarification of the origin of the mass of fundamental particles. However, it is often forgotten that the vast majority of visible matter is given by baryons, which gain most of their mass dynamically within poorly known non-perturbative quantum chromodynamics processes. The best laboratory to study the underlying mechanisms of non-perturbative quantum chromodynamics is still given by the nucleon and the central question of how the macroscopic properties of a nucleon like its mass, spin and size can be comprehensively decomposed into the microscopic description in terms of quarks, antiquarks and gluons remains still open. A major part of the COMPASS-II program is dedicated to the investigation of Generalized Parton Distributions (GPDs), which aim for the most complete description of the partonic structure of the nucleon, comprising both, spacial and kinematic distributions. By including transverse degrees of freedom, a three dimensional picture of baryonic matter is created, which will revolutionise our understanding of what comprises 99 percent of the visible matter. GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular the Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). At COMPASS, those processes are investigated using a high intensity muon beam of 160 GeV/c together with a 2.5 m-long liquid hydrogen target and an open field two stage spectrometer, to detect and identify charged and neutral particles. In order to optimize the selection of exclusive reactions at those energies, the target is surrounded by a new barrel-shaped time-of-flight system, which detects the recoiling target particles. A pilot run dedicated to the measurement of Generalized Parton distributions performed in 2012 allows for detailed performance studies

  6. Renormalization in Large Momentum Effective Theory of Parton Physics.

    Science.gov (United States)

    Ji, Xiangdong; Zhang, Jian-Hui; Zhao, Yong

    2018-03-16

    In the large-momentum effective field theory approach to parton physics, the matrix elements of nonlocal operators of quark and gluon fields, linked by straight Wilson lines in a spatial direction, are calculated in lattice quantum chromodynamics as a function of hadron momentum. Using the heavy-quark effective theory formalism, we show a multiplicative renormalization of these operators at all orders in perturbation theory, both in dimensional and lattice regularizations. The result provides a theoretical basis for extracting parton properties through properly renormalized observables in Monte Carlo simulations.

  7. Possible signatures of the hadronisation scale in parton jets

    International Nuclear Information System (INIS)

    Ochs, W.

    1987-01-01

    Models for hardon production in hard collisions differ widely in the energy scale characteristic of the transition from the primary partonic to the secondary hadronic phase of jet evolution. We investigate possible experimental signatures for the existence of both phases. In particular, we consider multiplicity and energy moments, long range charge correlations and angular correlations as a function of total energy or near the exclusive two body limit in e + e - annihilation and deep inelastic scattering processes. The possibility of a dual correspondence between hadronic and partonic states is discussed. (orig.)

  8. Probing lumps of wee partons in deep inelastic scattering

    International Nuclear Information System (INIS)

    Buchmueller, W.

    1994-06-01

    Recently, the ZEUS collaboration has reported on several remarkable properties of events with a large rapidity gap in deep inelastic scattering. We suggest that the mechanism underlying these events is the scattering of electrons off lumps of wee partons inside the proton. Based on an effective lagrangian approach the Q 2 -, x- and W-distributions are evaluated. For sufficiently small invariant mass of the detected hadronic system, the mechanism implies leading twist behaviour. The x- and W-distributions are determined by the Lipatov exponent which governs the behaviour of parton densities at small x. (orig.)

  9. Determination of the 3Pj phase shifts from nucleon-nucleon data: a critical evaluation and a surprising result

    International Nuclear Information System (INIS)

    Tornow, T.; Tornow, W.

    1999-01-01

    It Is shown that the 3 P j neutron-proton (proton-proton) phase shifts cannot be determined to less than ± 100 % (± 20 %) uncertainty at low energies (∼ 10 MeV), even if high-accuracy nucleon-nucleon data were to become available for currently inaccessible observables. For a more accurate determination, appropriate theoretical constraints have to be invoked, but their accuracy can be judged only from the comparison of rigorous three-nucleon continuum calculations with particular three-nucleon observables. (author)

  10. The charge form factor of three-nucleon systems and the polarization of the bound nucleon

    International Nuclear Information System (INIS)

    Giannini, M.M.; Drechsel, D.; Arenhoevel, H.; Tornow, V.

    1979-01-01

    The discrepancy between theoretical calculations of the 3 He charge density and the results derived from elastic electron scattering may be due to the analysis of the experimental data in terms of spherical nucleons. A classical model with deformed nucleons gives qualitive agreement with experiment for an oblate quadrupole moment of -1.8 mb. Such a deformation of the bound nucleon can be described by the admixture of Δ(1232) and higher isobar components with spin >= 3/2. Since the admixture probabilities are small the dominant contributions stem from the transition quadrupole moments between free nucleon and isobar components. Taking into account the leading Δ(1232) components one can explain about half of the discrepancy. As this transition operator is isovector, the effects are opposite for 3 He and 3 H. (orig.)

  11. How dense does parton matter get in Pb + Pb collisions at the CERN SPS?

    International Nuclear Information System (INIS)

    Geiger, K.; Mueller, B.

    1998-01-01

    The qualitative features of parton production through materialization in heavy-ion collisions are examined within perturbative QCD, and the magnitude of the resulting parton density created during the early stage of the collisions is estimated. The implications for 'anomalous' J/ψ suppression observed in Pb + Pb collisions at the CERN SPS are discussed. The A-dependence of absorption of J/ψ by (partonic) comovers is steeper than assumed in most phenomenological models, because the absorption process is dominated by quasi-perturbative QCD interactions. The argument is supported by results recently obtained in the framework of the parton cascade model. Significant 'anomalous' suppression for Pb + Pb collisions at the CERN-SPS are predicted, but not for S + U collisions. (author)

  12. Three-nucleon forces and their importance in three-nucleon sys- tems and heavier nuclei

    NARCIS (Netherlands)

    Kalantar-Nayestanaki, N.

    2014-01-01

    Abstract In the past two decades, several laboratories have produced a large amount of data for cross sections, analyzing powers, and other spin observables from various reactions in the three-nucleon system. The experimental results are moderately described by only using the two-nucleon potentials

  13. Correlations in the Parton Recombination Model

    Energy Technology Data Exchange (ETDEWEB)

    Bass, S.A. [Department of Physics, Duke University, Durham, NC 27708-0305 (United States); RIKEN BNL Research Center, Brookhaven Nat. Lab., Upton, NY 11973 (United States); Fries, R.J. [School of Physics and Astronomy, Univ. of Minnesota, Minneapolis, MN 55455 (United States); Mueller, B. [Department of Physics, Duke University, Durham, NC 27708-0305 (United States)

    2006-08-07

    We describe how parton recombination can address the recent measurement of dynamical jet-like two particle correlations. In addition we discuss the possible effect realistic light-cone wave-functions including higher Fock-states may have on the well-known elliptic flow valence-quark number scaling law.

  14. Color oscillations of nucleons in a nucleus

    International Nuclear Information System (INIS)

    Petrov, V.A.; Smirnov, A.Yu.

    1987-01-01

    Possibility of nucleus description as an object consisting of quarks and gluons is considered. A model of two-nucleon interaction in a nucleus is presented and analytical expressions for the nucleus nucleon ground state wave functions and also for nuclear nucleon structure functions are obtained. The carried out analysis shows that the suggested model permits to express the nucleus structure functions at quark level only by means of nucleon and Δ-isobaric degrees of freedom

  15. Structure functions are not parton probabilities

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.; Hoyer, Paul; Sannino, Francesco; Marchal, Nils; Peigne, Stephane

    2002-01-01

    The common view that structure functions measured in deep inelastic lepton scattering are determined by the probability of finding quarks and gluons in the target is not correct in gauge theory. We show that gluon exchange between the fast, outgoing partons and target spectators, which is usually assumed to be an irrelevant gauge artifact, affects the leading twist structure functions in a profound way. This observation removes the apparent contradiction between the projectile (eikonal) and target (parton model) views of diffractive and small x B phenomena. The diffractive scattering of the fast outgoing quarks on spectators in the target causes shadowing in the DIS cross section. Thus the depletion of the nuclear structure functions is not intrinsic to the wave function of the nucleus, but is a coherent effect arising from the destructive interference of diffractive channels induced by final state interactions. This is consistent with the Glauber-Gribov interpretation of shadowing as a rescattering effect

  16. Qualitative treatment of three-nucleon properties

    International Nuclear Information System (INIS)

    Efimov, V.

    1981-01-01

    An attempt is made at consistent qualitative treatment of the three-nucleon system. The approach used is based on the physical concept of effective three-nucleon long-range interaction resulting from the existence of the deuteron and the virtual singlet deuteron. Within the framework of the approach, a qualitative treatment of the triton properties, nucleon-deuteron scattering, and triton-disintegration reactions is carried out. The following topics are dealt with: the Phillips line, the triton D-wave admixture, the doublet effective range of the n-d scattering, the triton virtual state, the anomaly of the n-d elastic cross section near the three-body threshold, and the partial cross sections of the inelastic n-d scattering and of the triton photo- and electrodisintegration. The discussion of these topics includes the evaluation of three-nucleon parameters and the qualitative interpretation of experimental data and calculation results; some predictions are also made. The results of our analysis lead to the conclusion that the concept of effective three-nucleon long-range interaction can indeed serve as grounds for consistent qualitative treatment of the three-nucleon phenomena. (orig.)

  17. Probing nuclear structure with nucleons

    International Nuclear Information System (INIS)

    Bauge, E.

    2007-01-01

    The goal of this lecture is to show how nucleon scattering can be used to probe the structure of target nuclei, and how nucleon scattering observables can be interpreted in terms of nuclear structure using microscopic optical potentials. After a brief overview of the specificities of nucleon-nucleus scattering, and a quick reminder on scattering theory, the main part of this lecture is devoted to the construction of optical potentials in which the target nuclei structure information is folded with an effective interaction. Several examples of such microscopic optical model potentials are given. (author)

  18. Hard scattering on light nuclei: a convenient way to study parton correlations

    International Nuclear Information System (INIS)

    Calucci, G.; Treleani, D.

    2011-01-01

    The one-body partonic distributions in the hadrons are well investigated using electromagnetic or weak interactions. If we wish to exploit the same procedure to study the two-body distributions we should study the very rare events with multiple electromagnetic or weak interactions on the same hadron.The alternative is to study events with hard QCD double scattering of partons of the same hadron, such events become more and more abundant when the energy of the colliding hadrons grows. In fact at very high energies even the parton at small fractional momentum χ may suffer collisions with momentum transfer large enough to allow a perturbative treatment

  19. Coulomb effects in three-nucleon scattering versus charge-symmetry breaking in the 3P nucleon-nucleon interactions

    International Nuclear Information System (INIS)

    Tornow, W.; Howell, C.R.; Walter, R.L.; Slaus, I.

    1992-01-01

    Comparison of data for neutron-deuteron and proton-deuteron analyzing power A y for elastic scattering has become crucial for investigating charge-symmetry breaking in the 3 P nucleon-nucleon interactions. We extended this comparison down to 5 MeV and find that the relative difference between n-d and p-d scattering at the A y maximum near 120 degree increases with decreasing energy. By applying a straightforward Coulomb ''correction'' to the p-d data, we account for most of the difference, suggesting that the Coulomb force, rather than charge-symmetry breaking, is responsible for most of the observed difference

  20. QED radiative correction for the single-W production using a parton shower method

    International Nuclear Information System (INIS)

    Kurihara, Y.; Fujimoto, J.; Ishikawa, T.; Shimizu, Y.; Kato, K.; Tobimatsu, K.; Munehisa, T.

    2001-01-01

    A parton shower method for the photonic radiative correction is applied to single W-boson production processes. The energy scale for the evolution of the parton shower is determined so that the correct soft-photon emission is reproduced. Photon spectra radiated from the partons are compared with those from the exact matrix elements, and show a good agreement. Possible errors due to an inappropriate energy-scale selection or due to the ambiguity of the energy-scale determination are also discussed, particularly for the measurements on triple gauge couplings. (orig.)