Evidence for a positive longitudinal double-spin asymmetry 〈Aρ1〉 = 0.24 ± 0.11stat ± 0.02syst in the cross section for exclusive diffractive ρ(770) vector meson production in polarised lepton-proton scattering was observed by the HERMES experiment. The longitudinally polarised 27.56 GeV HERA positron beam was scattered off a longitudinally polarised pure hydrogen gas target. The average invariant mass of the photon-proton system has a value of 〈W 〉 = 4.9 GeV, while the average negative squared four-momentum of the virtual photon is 〈Q〉 = 1.7 GeV. The ratio of the present result to the corresponding spin asymmetry in inclusive deep-inelastic scattering is in agreement with an early theoretical prediction based on the generalised vector meson dominance model. PACS numbers : 13.25.-k; 13.40.-f; 13.60.-r; 13.60.Le; 13.88.+e; 14.40.Cs

A. Airapetian, N. Akopov, Z. Akopov, M. Amarian, 31 V.V. Ammosov, A. Andrus, E.C. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetissian, P. Bailey, D. Balin, V. Baturin, M. Beckmann, S. Belostotski, S. Bernreuther, N. Bianchi, H.P. Blok, 29 H. Böttcher, A. Borissov, A. Borysenko, M. Bouwhuis, J. Brack, A. Brüll, V. Bryzgalov, G.P. Capitani, T. Chen, H.C. Chiang, G. Ciullo, M. Contalbrigo, P.F. Dalpiaz, R. De Leo, M. Demey, L. De Nardo, E. De Sanctis, E. Devitsin, P. Di Nezza, J. Dreschler, M. Düren, M. Ehrenfried, A. Elalaoui-Moulay, G. Elbakian, F. Ellinghaus, U. Elschenbroich, R. Fabbri, A. Fantoni, A. Fechtchenko, L. Felawka, B. Fox, S. Frullani, G. Gapienko, V. Gapienko, F. Garibaldi, K. Garrow, E. Garutti, D. Gaskell, G. Gavrilov, 27 V. Gharibyan, G. Graw, O. Grebeniouk, L.G. Greeniaus, 27 I.M. Gregor, K. Hafidi, M. Hartig, D. Hasch, D. Heesbeen, M. Henoch, R. Hertenberger, W.H.A. Hesselink, 29 A. Hillenbrand, M. Hoek, Y. Holler, B. Hommez, G. Iarygin, A. Ivanilov, A. Izotov, H.E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, M. Kopytin, V. Korotkov, V. Kozlov, B. Krauss, V.G. Krivokhijine, L. Lagamba, L. Lapikás, A. Laziev, 29 P. Lenisa, P. Liebing, L.A. Linden-Levy, K. Lipka, W. Lorenzon, H. Lu, J. Lu, S. Lu, B.-Q. Ma, B. Maiheu, N.C.R. Makins, Y. Mao, B. Marianski, H. Marukyan, F. Masoli, V. Mexner, N. Meyners, O. Mikloukho, C.A. Miller, 27 Y. Miyachi, V. Muccifora, A. Nagaitsev, E. Nappi, Y. Naryshkin, A. Nass, M. Negodaev, W.-D. Nowak, K. Oganessyan, H. Ohsuga, N. Pickert, S. Potashov, D.H. Potterveld, M. Raithel, D. Reggiani, P.E. Reimer, A. Reischl, A.R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, L. Rubacek, J. Rubin, D. Ryckbosch, Y. Salomatin, I. Sanjiev, 22 I. Savin, A. Schäfer, C. Schill, G. Schnell, 28 K.P. Schüler, J. Seele, R. Seidl, B. Seitz, R. Shanidze, C. Shearer, T.-A. Shibata, V. Shutov, M.C. Simani, 29 K. Sinram, M. Stancari, M. Statera, E. Steffens, J.J.M. Steijger, H. Stenzel, J. Stewart, F. Stinzing, U. Stösslein, P. Tait, H. Tanaka, S. Taroian, B. Tchuiko, A. Terkulov, A. Tkabladze, A. Trzcinski, M. Tytgat, A. Vandenbroucke, P.B. van der Nat, 29 G. van der Steenhoven, M.C. Vetterli, 27 V. Vikhrov, M.G. Vincter, C. Vogel, M. Vogt, J. Volmer, C. Weiskopf, J. Wendland, 27 J. Wilbert, Y. Ye, Z. Ye, S. Yen, B. Zihlmann, and P. Zupranski

K. Ackerstaff6, A. Airapetian36, N. Akopov36, I. Akushevich7, M. Amarian26,31,36, E.C. Aschenauer7,14,26, H. Avakian11, R. Avakian36, A. Avetissian36, B. Bains16, S. Barrow28, C. Baumgarten24, M. Beckmann13, S. Belostotski29, J.E. Belz32,33, Th. Benisch9, S. Bernreuther9, N. Bianchi11, S. Blanchard25, J. Blouw26, H. Böttcher7, A. Borissov6,15, J. Brack5, B. Bray4, S. Brauksiepe13, B. Braun9,24, St. Brons7, W. Brückner15, A. Brüll15, E.E.W. Bruins21, H.J. Bulten19,26,35, R.V. Cadman16, G.P. Capitani11, P. Carter4, P. Chumney25, E. Cisbani31, G.R. Court18, P. F. Dalpiaz10, R. De Leo3, P.P.J. Delheij33, E. De Sanctis11, D. De Schepper2,21, E. Devitsin23, P.K.A. de Witt Huberts26, P. Di Nezza11, M. Düren9, A. Dvoredsky4, J. Ely5, G. Elbakian36, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B.W. Filippone, H. Fischer, H.T. Fortune28, B. Fox5, S. Frabetti10, J. Franz13, S. Frullani31, M.-A. Funk6, N.D. Gagunashvili8, P. Galumian1, H. Gao2,16,21, Y. Gärber7, F. Garibaldi31, G. Gavrilov29, P. Geiger15, V. Gharibyan36, A. Golendukhin6,20,24,36, G. Graw24, O. Grebeniouk29, P.W. Green1,33, L.G. Greeniaus1,33, C. Grosshauser9, M. Guidal26, A. Gute9, V. Gyurjyan11, J.P. Haas25, W. Haeberli19, J.-O. Hansen2, D. Hasch7, O. Häusser†32,33, R. Henderson33, F.H. Heinsius13, Th. Henkes26, M. Henoch9, R. Hertenberger24, Y. Holler6, R.J. Holt16, W. Hoprich15, H. Ihssen6,26, M. Iodice31, A. Izotov29, H.E. Jackson2, A. Jgoun29, C. Jones2, R. Kaiser7,32,33, M. Kestel13, E. Kinney5, M. Kirsch9, A. Kisselev29, P. Kitching1, H. Kobayashi34, N. Koch20, K. Königsmann13, M. Kolstein26, H. Kolster24, V. Korotkov, W. Korsch, V. Kozlov, L.H. Kramer, B. Krause, V.G. Krivokhijine, M. Kückes, F. Kümmell13, M. Kurisuno34, G. Kyle25, W. Lachnit9, W. Lorenzon22,28, A. Lung4, N.C.R. Makins2,16, F.K. Martens1, J.W. Martin21, H. Marukyan36, F. Masoli10, A. Mateos21, M. Maul30, M. McAndrew18, K. McIlhany4,21, R.D. McKeown4, F. Meissner7, F. Menden13,33, D. Mercer5, A. Metz24, N. Meyners6 O. Mikloukho29, C.A. Miller1,33, M.A. Miller16, R. Milner21, V. Mitsyn8, A. Most16,22,28, R. Mozzetti11, V. Muccifora11, A. Nagaitsev8, E. Nappi3, Yu. Naryshkin29, A.M. Nathan16, F. Neunreither9, J.M. Niczyporuk16,21, W.-D. Nowak7, M. Nupieri11, P. Oelwein15, H. Ogami34, T.G. O’Neill2, R. Openshaw33, B.R. Owen16, J. Ouyang33, V. Papavassiliou25, S.F. Pate21,25, M. Pitt4, H.R. Poolman26, S. Potashov23, D.H. Potterveld2, G. Rakness5, A. Reali, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, G. Röper, P. Rossi, S. Rudnitsky, M. Ruh13, D. Ryckbosch14, Y. Sakemi34, I. Savin8, C. Scarlett22, A. Schäfer30, F. Schmidt9, H. Schmitt13, G. Schnell25, K.P. Schüler6, A. Schwind7, J. Seibert13, T.-A. Shibata34, K. Shibatani34, T. Shin21, V. Shutov8, C. Simani10, A. Simon13,25, K. Sinram6, P. Slavich10,11, W.R. Smythe5, J. Sowinski15, M. Spengos6,28, E. Steffens9, J. Stenger9, J. Stewart18, F. Stock9,15, U. Stoesslein7, M. Sutter21, H. Tallini18, S. Taroian36, A. Terkulov23, D.M. Thiessen32,33, B. Tipton21, E. Thomas11, A. Trudel33, M. Tytgat14, G.M. Urciuoli31, J.J. van Hunen26, R. van de Vyver14, J.F.J. van den Brand26,35, G. van der Steenhoven26, M.C. Vetterli32,33, V. Vikhrov29, M. Vincter33, J. Visser26, E. Volk15, W. Wander9,21, T.P. Welch27, J. Wendland32,33, S.E. Williamson16, T. Wise19, K. Woller6, S. Yoneyama, K. Zapfe, H. Zohrabian, R. Zurmühle Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada Physics Division, Argonne National Laboratory, Argonne, Illinois 60439-4843, USA Istituto Nazionale di Fisica Nucleare, Sezione di Bari, 70124 Bari, Italy W.K. Kellogg Radiation Lab, California Institute of Technology, Pasadena, California 91125, USA Nuclear Physics Laboratory, University of Colorado, Boulder, Colorado 80309-0446, USA DESY, Deutsches Elektronen Synchrotron, 22603 Hamburg, Germany DESY Zeuthen, 15738 Zeuthen, Germany Joint Institute for Nuclear Research, 141980 Dubna, Russia Physikalisches Institut, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara and Dipartimento di Fisica, Università di Ferrara, 44100 Ferrara,

A single-spin asymmetry was measured in the azimuthal distribution of pi+pi- pairs produced in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target. For the first time, evidence is found for a correlation between the transverse target polarization and the azimuthal orientation of the plane containing the two pions.The corresponding single-spin asymmetry is expected to be related to the product of the little-known quark transversity distribution function and an unknown naive-T-odd chiral-odd dihadron fragmentation function.

K. Ackerstaff, A. Airapetian, I. Akushevich, N. Akopov, M. Amarian, E.C. Aschenauer, R. Avakian, H. Avakian, A. Avetissian, B. Bains, S. Barrow, M. Beckmann, S. Belostotski, J.E. Belz, Th. Benisch, S. Bernreuther, N. Bianchi, S. Blanchard, J. Blouw, H. Böttcher, A. Borissov, J. Brack, B. Braun, B. Bray, W. Brückner, A. Brüll, E.E.W. Bruins, H.J. Bulten, G.P. Capitani, P. Carter, E. Cisbani, G.R. Court, P.P.J. Delheij, E. Devitsin, C.W. de Jager, E. De Sanctis, D. De Schepper, P.K.A. de Witt Huberts, M. Düren, A. Dvoredsky, G. Elbakian, J. Emerson, A. Fantoni, A. Fechtchenko, M. Ferstl, D. Fick, K. Fiedler, B.W. Filippone, H. Fischer, H.T. Fortune, J. Franz, S. Frullani, M.-A. Funk, N.D. Gagunashvili, P. Galumian, H. Gao, Y. Gärber, F. Garibaldi, P. Geiger, V. Gharibyan, A. Golendoukhin, G. Graw, O. Grebeniouk, P.W. Green, L.G. Greeniaus, C. Grosshauser, A. Gute, V. Gyurjyan, J.P. Haas, W. Haeberli, J.-O. Hansen, D. Hasch, O. Häusser, R.S. Henderson, Th. Henkes, R. Hertenberger, Y. Holler, R.J. Holt, H. Ihssen, M. Iodice, A. Izotov, H.E. Jackson, A. Jgoun, C. Jones, R. Kaiser, E. Kinney, M. Kirsch, A. Kisselev, P. Kitching, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, W. Korsch, V. Kozlov, L.H. Kramer, B. Krause, V.G. Krivokhijine, M. Kückes, G. Kyle, W. Lachnit, W. Lorenzon, A. Lung, N.C.R. Makins, S.I. Manaenkov, F.K. Martens, J.W. Martin, A. Mateos, K. McIlhany, R.D. McKeown, F. Meissner, D. Mercer, A. Metz, N. Meyners, O.Mikloukho, C.A. Miller, M.A. Miller, R.G. Milner, V. Mitsyn, A. Most, R. Mozzetti, V. Muccifora, A. Nagaitsev, Y. Naryshkin, A.M. Nathan, F. Neunreither M. Niczyporuk, W.-D. Nowak, M. Nupieri, P. Oelwein, H. Ogami, T.G. O’Neill, R. Openshaw, V. Papavassiliou, S.F. Pate, M. Pitt, S. Potashov, D.H. Potterveld, B. Povh, G. Rakness, R. Redwine, A.R. Reolon, R. Ristinen, K. Rith, G. Röper, H. Roloff, P. Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, K.P. Schüler, A. Schwind, T.-A. Shibata, T. Shin, A. Simon, K. Sinram, W.R. Smythe, J. Sowinski, M. Spengos, E. Steffens, J. Stenger, J. Stewart, F. Stock, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, D.M. Thiessen, B. Tipton, A. Trudel, M. Tytgat, G.M. Urciuoli, R. Van de Vyver, J.F.J. van den Brand, G. van der Steenhoven, M.C. Vetterli, E. Volk, W. Wander, T.P. Welch, S.E. Williamson, T. Wise, T. Wölfel, K. Zapfe-Düren, H. Zohrabian, R. Zurmühle

A measurement of the beam-spin asymmetry in the azimuthal distribution of pions produced in semi-inclusive deep-inelastic scattering off protons is presented. The measurement was performed using the HERMES spectrometer with a hydrogen gas target and the longitudinally polarized 27.6 GeV positron beam of HERA. The sinusoidal amplitude of the dependence of the asymmetry on the angle phi of the hadron production plane around the virtual photon direction relative to the lepton scattering plane was measured for pi(+), pi(-) and pi(0) mesons. The dependence of this amplitude on the Bjorken scaling variable and on the pion fractional energy and transverse momentum is presented. The results are compared to theoretical model calculations. (C) 2007 Elsevier B.V. All rights reserved.

This report presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC). The collisions of lead nuclei at energies , will probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research is to study the fundamental theory of the strong interaction ? Quantum Chromodynamics (QCD) ? in extreme conditions of temperature, density and parton momentum fraction (low-x).This report covers in detail the potential of CMS to carry out a series of representative Pb-Pb measurements. These include bulk observables, (charged hadron multiplicity, low pT inclusive hadron identified spectra and elliptic flow) which provide information on the collective properties of the system, as well as perturbative probes such as quarkonia, heavy-quarks, jets and high pT hadrons which yield tomographic information of the hottest and densest phases of the reaction.

The first observation of an azimuthal cross section asymmetry with respect to the charge of the incoming lepton beam is reported from a study of hard exclusive electroproduction of real photons. The data have been accumulated by the HERMES experiment at DESY, in which the HERA 27.6 GeV electron or positron beam scattered off an unpolarized hydrogen gas target. The observed asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply virtual Compton scattering (DVCS) process. The interference term is sensitive to DVCS amplitudes, which provide the most direct access to generalized parton distributions.

Measurements of the cross section for exclusive virtual-photoproduction of 0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident on a hydrogen gas target in the HERA storage ring. The invariant mass W of the photon-nucleon system ranges from 4.0 to 6.0 GeV, while the negative squared four-momentum Q 2 of the virtual photon varies from 0.7 to 5.0 GeV 2. The present data together with most of the previous data at W > 4 GeV are well described by a model that infers the W-dependence of the cross section from the dependence on the Bjorken scaling variable x of the unpolarized structure function for deep-inelastic scattering. In addition, a model calculation based on OO-Forward Parton Distributions gives a fairly good account of the longitudinal component of the 0 production cross section for Q 2 > 2 GeV 2. 2

Precise measurements of the spin structure functions of the proton g(1)(p)(x,Q(2)) and deuteron g(1)(d)(x,Q(2)) are presented over the kinematic range 0.0041 <= x <= 0.9 and 0.18 GeV2 <= Q(2)<= 20 GeV2. 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 targets internal to the HERA storage ring. The neutron spin structure function g(1)(n) is extracted by combining proton and deuteron data. The integrals of g(1)(p,d) at Q(2)=5 GeV2 are evaluated over the measured x range. Neglecting any possible contribution to the g(1)(d) integral from the region x <= 0.021, a value of 0.330 +/- 0.011(theo)+/- 0.025(exp)+/- 0.028(evol) is obtained for the flavor-singlet axial charge a(0) in a leading-twist next-to-next-to-leading-order analysis.

The HERMES experiment has measured the transverse polarization of A and A hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P Λ n of the A hyperon is found to be positive while the observed A polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P Λ n = 0.078± 0.006(stat) ± 0.012(syst) and P Λ n = -0.025 ± 0.015(stat) ± 0.018(syst) for A and A, respectively. The dependences of P Λ n and P Λ n on the fraction ζ of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p T were investigated. The measured A polarization rises linearly with p T and exhibits a different behavior for low and high values of ζ, which approximately correspond to the backward and forward regions in the center-of-mass frame of the γ*N reaction.

The HERMES experiment has measured the transverse polarization of Lambda and (Lambda) over bar hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P-n(Lambda) of the Lambda hyperon is found to be positive while the observed (Lambda) over bar polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P-n(Lambda)=0.078 +/- 0.006(stat)+/- 0.012(syst) and P-n((Lambda) over bar)=-0.025 +/- 0.015(stat)+/- 0.018(syst) for Lambda and (Lambda) over bar, respectively. The dependences of P-n(Lambda) and P-n((Lambda) over bar) on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p(T) were investigated. The measured Lambda polarization rises linearly with p(T) and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.