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Johannes Blรผmlein (Desy Zeuthen)17/04/2007, 09:00Spin PhysicsOverview on polarised PDFsGo to contribution page
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Krzysztof Kurek (Soltan Institute for Nuclear Studies)17/04/2007, 09:20Spin PhysicsResults on the deuteron longitudinal inclusive spin-dependent asymmetryA_1^d and the spindependentstructure function g_1^d are presented. The data have been collected by the COMPASS experiment at CERN during the years 2002-2004 using 160 GeV/c polarised muon beam scattered off a polarised 6LiD target. The obtained values for Gamma_1^d, the first moment of g_1^d(x), and for the...Go to contribution page
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Lara De Nardo (DESY / TRIUMF)17/04/2007, 09:40Spin PhysicsPrecise measurements of the spin structure functions $g_1^^p(x,Q2)$ and $g_1^n(x,Q2)$ are presented over the kinematic range 0.0041 $\leq x \leq $ 0.9 and 0.18 GeV$^2$ $\leq Q2 \leq $ 20 GeV$^2$. The data were collected at the HERMES experiment at DESY, in deep-inelastic scattering of 27.6 GeV longitudinally polarized positrons off longitudinally polarized hydrogen and deuterium gas...Go to contribution page
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Dimitar Stamenov (INRNE, Sofia)17/04/2007, 10:00Spin PhysicsThe results of a new NLO QCD analysis of the world data on inclusive polarized DIS are presented. The very precise CLAS proton and deuteron data, as well as the latest COMPASS data on the asymmetry $A_1^d$ were included in the analysis, and the impact of these data on polarized parton densities and higher twist effects has been studied. It is demonstrated that the low Q^2 CLAS data...Go to contribution page
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Keith Griffioen (College of William & Mary)17/04/2007, 10:20Spin PhysicsThe CLAS Collaboration at Jefferson Lab has a sustained and comprehensive program measuring the spin structure function g_1 for the proton and deuteron at low and intermediate Q2. Precise data with extensive kinematic coverage allow us to better constrain the polarized parton distributions and to accurately determine various moments of g_1 as a function of Q2. Our latest results will be...Go to contribution page
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Christof HENDLMEIER (University of Regensburg)17/04/2007, 11:10Spin PhysicsWe consider the photoproduction of two hadrons in polarized lepton-nucleon collisions in the framework of perturbative QCD. After illustrating how to obtain the experimentally relevant observables a detailed phenomenological study of the photoproduction of hadron pairs at high transverse momenta is presented. We show theoretical predictions for the relevant cross sections and double-spin...Go to contribution page
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Patricia Liebing (RIKEN / BNL)17/04/2007, 11:30Spin PhysicsHERMES has used a high statistics data sample of charged inclusive hadrons to measure double spin asymmetries as a function of p_T. From these asymmetries Delta g/g has been extracted in the region of 1<p_T<2 GeV, corresponding to x\approx0.2-0.3 The information on the background asymmetry and the subprocess kinematics has been obtained from a Leading Order Monte Carlo model and...Go to contribution page
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Susanne Koblitz (Institut fuer Kernphysik / Universitaet Mainz)17/04/2007, 11:50Spin PhysicsOne of the main goals of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon, Delta G/G. It is determined from spin asymmetries measured in the scattering of 160GeV/c polarised muons on a polarised LiD target. The gluon is accessed by the selection of photon-gluon fusion events. A selection of PGF events can be obtained with charmed mesons in the...Go to contribution page
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Kensuke Okada (Riken / BNL)17/04/2007, 12:10Spin PhysicsTo study the proton spin structure, the Relativistic Heavy Ion Collider (RHIC) at BNL provides a unique opportunity by colliding polarized protons. The hard subprocesses in proton-proton collisions involve gluons in leading order, therefore measurements of cross section asymmetries between aligned and anti aligned proton helicities give us information about the spin dependent gluon...Go to contribution page
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Renee Fatemi (MIT)17/04/2007, 12:30Spin PhysicsRecent STAR results on jet production in polarized p+p collisions at 200GeV at RHICGo to contribution page
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Frank Simon (MIT)17/04/2007, 14:00Spin PhysicsRecent STAR results on hadron production in polarized p+p collisions at 200GeV at RHICGo to contribution page
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Alexander Korzenev (Mainz University)17/04/2007, 14:20Spin PhysicsA first evaluation of the polarized valence quark distribution\Delta u_v(x)+Delta d_v(x) from the COMPASS experiment (CERN/SPS) is presented. The data were collected by COMPASS in the years 2002--2004 using a 160 GeV polarized muon beam scattered off a large polarized 6LiD target and cover the range 1< Q2 < 100(GeV/c)2 and $0.006<x<0.7. The analysis is based on the difference...Go to contribution page
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Philip Cole (Idaho State University)17/04/2007, 14:40Spin PhysicsA comprehensive program with polarized electron and photon probes with unpolarized and polarized proton and duteron targets is undergoing at JLab. Results and perspectives will be reported.Go to contribution page
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Karl Slifer (University of Virginia)17/04/2007, 15:00Spin PhysicsWe have measured the spin structure of the nucleon in the region of the resonances (final state mass W <2 GeV) at intermediate four-momentum transfer Q2 ~ 1.3 (GeV/c)2. Double-spin inclusive asymmetries for longitudinally polarized 5.75 GeV electrons incident on longitudinal and transverse solid polarized targets were measured in Jefferson Lab's Hall C. Frozen ammonia and deuterated...Go to contribution page
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Boris Ermolaev (Ioffe Physico-Technical Institute)17/04/2007, 15:20Spin PhysicsStandard Approach (SA) for description of $g_1$ is based on the DGLAP evolution equations and the special fits for the initial parton densities. SA accounts for the total resummation of logs of $Q2$ and lacks the total resummation of leading $ln(1/x)$. In order to meet the small -$x$ experimental data, SA includes phenomenological singular factors in the fits. They mimic the...Go to contribution page
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Ralf Seidl (University of Illinois at Urbana-Champaign)17/04/2007, 16:10Spin PhysicsIn order to obtain precise information on helicity and transversity distributions from semi-inclusive measurements in DIS and proton-proton collisions a good knowledge of fragmentation functions is necessary. The Belle experiment at the asymmetric e+e- collider KEKB can provide precise spin averaged and spin dependent fragmentation functions such as the Collins function and the...Go to contribution page
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Markus Diefenthaler (Physikalisches Institut II, Friedrich-Alexander-Universitรคt)17/04/2007, 16:30Spin PhysicsIn 2005 the HERMES collaboration published first evidence for azimuthal single-spin asymmetries in semi-inclusive production of charged pions on a transversely polarised hydrogen target. The measured asymmetries are caused by both the Collins and the Sivers mechanisms. Their distinctive Fourier components provide signals to previously unmeasured quantities: the transversity quark...Go to contribution page
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Andrea Bressan (INFN Trieste)17/04/2007, 16:50Spin PhysicsThe CERN COMPASS experiment is on the floor collecting data since 2002; in the years 2002, 2003, and 2004 data were collected using a 160 GeV polarized muon beam and a 6LiD polarized target. In about 20% of the running time the target polarisation was oriented transversely with respect to the muon beam direction to measure transverse spin effects in semi inclusive deep inelastic...Go to contribution page
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Umberto D'Alesio (Dipartimento di Fisica, Cagliari University)17/04/2007, 17:10Spin PhysicsWe present a global analysis of azimuthal asymmetries in e^+e^- -> h_1 h_2 X processes (BELLE data) and in semi-inclusive deep inelasticscattering (HERMES and COMPASS data). It results in the extraction of the Collins fragmentation function and of the transversity distribution function for u and d quarks. Theseturn out to have opposite signs and to be sizably smaller than...Go to contribution page
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Leonard Gamberg (Penn State Berks, Dept. of Physics)17/04/2007, 17:30Spin PhysicsThis talk will focus on transverse quark spin effects in SIDIS. I will discuss the theoretical T-odd input to the cos 2\phi azimuthal asymmetry as well as new work on the Collins function and the Boer Mulders function, the essential TMD inputs to this asymmetry. We will present new estimates of the cos2\phi asymmetry as a function of P_T, x, and z. I will also talk a bit about the...Go to contribution page
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Yury Naryshkin (Petersburg Nuclear Physics Institute)18/04/2007, 11:10Spin PhysicsTransverse Lambda and Lambda-bar polarization produced inclusively in quasi-real photon-nucleon scattering have been studied in the HERMES experiment using a 27.6 GeV positron beam incident on hydrogen and deuterium gas targets. The average transverse polarizations were found to be P^{Lambda}_n = 0.078 +- 0.006(stat) +- 0.012(syst) and P^{bar Lambda}_n = -0.025 +- 0.015(stat) +-0.018...Go to contribution page
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K. Oleg Eyser (UC Riverside, DESY)18/04/2007, 11:30Spin PhysicsWith recent experimental measurements of various asymmetries at HERMES[1], Belle[2], STAR[3], and BRAHMS[4] there has been a growing interest in the understanding of the transversely polarized proton structure. Theoretical explanations include different mechanisms, such as effects from the Sivers function, the Collins effect, higher twist contributions, or combinations of all of the above....Go to contribution page
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Steven Heppelmann (Penn State)18/04/2007, 11:50Spin Physics
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J.H. Lee (BNL)18/04/2007, 12:10Spin PhysicsSingle transverse spin asymmetries (SSA) in transversely polarised pp reactions at the energy regime where pQCD is applicable are expected to be negligibly small in the lowest-oredr QCD approximation, whereas experimentally large SSAs have been observed at high xF. Recently, new measurements of SSAs have been available from semi-inclusive deep-inelastic scattering and transversely polarised pp...Go to contribution page
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Philipp Haegler (TU Muenchen)18/04/2007, 12:30Spin PhysicsIn this talk, we present recent results from lattice QCD on the transverse spin structure of hadrons. Strong correlations between spin, orbital angular momentum and coordinate degrees of freedom lead to strongly distorted densities of quarks in hadrons in particular for transverse quark polarizations. We discuss possible implications of our results for the Sivers and Boer-Mulders function...Go to contribution page
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Hiroyuki Kawamura (RIKEN)19/04/2007, 09:00Spin PhysicsWe study the double-spin asymmetries in transversly/longitudinally polarized Drell-Yan processes at transverse momentum Q_T of the produced lepton pair. We first consider the double transverse-spin asymmetry A_{TT}(Q_T) in the transversely polarized Drell-Yan process in detail, in particular, in the small Q_T region, where the bulk of dileptons are produced. The large logarithms due to...Go to contribution page
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Prof. Yuji Koike (Department of Physics, Niigata University)19/04/2007, 09:20Spin PhysicsWe present a consistent framework for the twist-3 calculation for the single transverse spin asymmetry (SSA). We prove that the consistent use of the Ward identity for color gauge invariance is crutial to obtain the factorization property and the gauge invariance of the twist-3 single-spin-dependent cross section. This proof had been missed in the previous literature. As an...Go to contribution page
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Prof. Kazuhiro Tanaka (Dept. of Physics, Juntendo University)19/04/2007, 09:40Spin PhysicsIt is known that a dominant QCD mechanism for the single transverse-spin asymmetry in hard processes is induced by the twist-3 quark-gluon correlations inside a hadron, combined with the soft-gluonic poles to produce the interfering phase for the associated partonic hard scattering. We show that the coupling of the relevant soft gluon to partonic subprocess can be systematically...Go to contribution page
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Cedran Bomhof (Vrije Universiteit Amsterdam)19/04/2007, 10:00Spin PhysicsThe Sivers effect is a possible source for many single spin asymmetries. The appearance of the Sivers distribution function is also a testinground for our understanding of universality. A well-known example of the peculiar universality property of this function is the relative sign difference of the Sivers function in SIDIS and Drell-Yan scattering. This opposite sign is a direct...Go to contribution page
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Jan Balewski (IUCF)19/04/2007, 10:20Spin Physics
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Alessandro Bacchetta (DESY)19/04/2007, 11:10Spin PhysicsThe cross section for polarized semi-inclusive deep inelastic scattering is reviewed, including in particular the dependence on the transverse momentum of the detected hadron. Out of the 18 structure functions appearing in the cross section, we will discuss the present knowledge of a few selected examples.Go to contribution page
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Christian Schill (Univ. Freiburg)19/04/2007, 11:30Spin PhysicsAn important missing piece in our understanding of the spin structure of the nucleon is the transversity distribution function Delta_Tq(x). It is only one of the three leading-twist quark distribution functions q(x), Delta q(x) and Delta_Tq(x) that so-far remains unmeasured. The function Delta_Tq(x) describes the distribution of transversely polarized quarks in a transversely polarized...Go to contribution page
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Marco Radici (INFN - Sezione Pavia)19/04/2007, 11:50Spin PhysicsWe consider dihadron fragmentation functions, that describe the fragmentation of a parton in two (unpolarized) hadrons. Using Jet calculus techniques, we develop evolution equations when these functions are explicitly depending upon the invariant mass of the produced hadron pair, the socalled extended dihadron fragmentation functions. We connect our results to the integrated dihadron...Go to contribution page
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Aram Kotzinian (INFN Torino)19/04/2007, 12:10Spin PhysicsIn semi-inclusive DIS of polarized leptons on a transversely polarized target eight azimuthal modulations appear in the cross-section. Within QCD parton model four azimuthal asymmetries can be interpreted at leading order, two of them being the already measured Collins and Sivers asymmetries. The other two leading twist asymmetries, related to different transverse momentum dependent quark...Go to contribution page
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John Lajoie (Iowa State University)19/04/2007, 12:30Spin PhysicsThe PHENIX upgrade program adds a set of silicon pixel detectors (the VTX and FVTX), forward calorimetry (the NCC), and Level-1 trigger detectors (the Muon Trigger Upgrade) to the baseline detector. These upgrades will enhance the ability of PHENIX to pursue a rich program of spin physics in polarized proton collisions, in particular at sqrt(s) = 500 GeV. The VTX and FVTX detectors will...Go to contribution page
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