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Flavour separation of helicity distributions from deep inelastic muon–deuteron scattering

2009; Elsevier BV; Volume: 680; Issue: 3 Linguagem: Inglês

10.1016/j.physletb.2009.08.065

1873-2445

M. Alekseev, V. Alexakhin, Yu. Alexandrov, G.D. Alexeev, A. Amoroso, A. Austregesilo, B. Badełek, F. Balestra, J. Ball, J. Barth, G. Baum, Y. Bedfer, J. Bernhard, R. Bertini, Marco Bettinelli, R. Birsa, J. Bisplinghoff, P. Bordalo, F. Bradamante, A. Bravar, A. Bressan, G. Brona, E. Burtin, M.P. Bussa, A. Chapiró, M. Chiosso, S. U. Chung, A. Cicuttin, M. Colantoni, M.L. Crespo, S. Dalla Torre, T. Dafní, Sudipta Das, S. Dasgupta, О. Денисов, L. Dhara, V. Diaz, A.M. Dinkelbach, S.V. Donskov, N. Doshita, V. Duic, W. Dünnweber, А.В. Ефремов, A. El Alaoui, P.D. Eversheim, W. Eyrich, M. Faessler, A. Ferrero, M. Finger, M. Finger, H. Fischer, C. Franco, J. Friedrich, R. Garfagnini, F. Gautheron, O.P. Gavrichtchouk, R. Gazda, S. Gerassimov, R. Geyer, M. Giorgi, B. Gobbo, S. Goertz, S. Grabmüller, O.A. Grajek, A. Grasso, B. Grube, R. Gushterski, A. Guskov, F. Haas, R. Hagemann, D. von Harrach, T. Hasegawa, J. Heckmann, F. H. Heinsius, R. Hermann, F. Herrmann, Christian Heß, F. Hinterberger, N. Horikawa, Ch. Höppner, N. d׳Hose, C. Ilgner, S. Ishimoto, O. N. Ivanov, Yu. Ivanshin, T. Iwata, R. Jahn, P. Jasinski, G. Jegou, R. Joosten, E. Kabuß, Wolfgang Käfer, Daekyoung Kang, B. Ketzer, G.V. Khaustov, Yu. Khokhlov, J. Kiefer, Yu. Kisselev, F. Klein, K. Klimaszewski, S. Koblitz, J.H. Koivuniemi, V.N. Kolosov, E.V. Komissarov, Kazuhiro Kondo, K. Königsmann, R. Konopka, I. Konorov, В.Ф. Константинов, A. Korzenev, A.M. Kotzinian, O. Kouznetsov, K. Kowalik, Markus Krämer, A. Král, Z. Kroumchtein, R. Kuhn, F. Kunne, K. Kurek, J.M. Le Goff, A.A. Lednev, A. Lehmann, S. Levorato, J. Lichtenstadt, T. Liška, A. Maggiora, M. Maggiora, A. Magnon, G.K. Mallot, A. Mann, C. Marchand, J. Marroncle, A. Martin, J. Marzec, F. Massmann, T. Matsuda, A.N. Maximov, W. Meyer, T. Michigami, Yu.V. Mikhailov, M.A. Moinester, A. Mutter, A. Nagaytsev, T. Nagel, J. Nassalski, Stefano Négrini, F. Nerling, S. Neubert, D. Neyret, V.I. Nikolaenko, А.G. Оlshevsky, M. Ostrick, A. Padee, R. Panknin, D. Panzieri, B. Parsamyan, S. Paul, B. Pawlukiewicz-Kaminska, E. Perevalova, G. Pesaro, D. V. Peshekhonov, G. Piragino, S. Platchkov, J. Pochodzalla, J. Polak, V.A. Polyakov, G. Pontecorvo, J. Pretz, C. Quintans, J.-F. Rajotte, S. Ramos, V. Rapatsky, G. Reicherz, D. Reggiani, A. Richter, F. Robinet, E. Rocco, E. Rondio, D.I. Ryabchikov, V. D. Samoylenko, A. Sandacz, H. Santos, M.G. Sapozhnikov, S. Sarkar, I. Savin, G. Sbrizzai, P. Schiavon, C. Schill, L. Schmitt, W. Schröder, O. Yu. Shevchenko, H.-W. Siebert, L. Silva, L. Sinha, A. Sissakian, M. Slunečka, G.I. Smirnov, S. Sosio, F. Sozzi, A. Srnka, M. Stolarski, M. Šulc, R. Sulej, S. Takekawa, S. Tessaro, F. Tessarotto, Andreas Teufel, L.G. Tkatchev, G. Venugopal, M. Virius, N.V. Vlassov, A. Vossen, Q. Weitzel, K. Wenzl, R. Windmolders, W. Wiślicki, H. Wollny, К. Заремба, M. Zavertyaev, E. Zemlyanichkina, M. Ziembicki, J. Zhao, N. Zhuravlev, A. Zvyagin,

Quantum Chromodynamics and Particle Interactions

We present a LO evaluation of helicity densities of valence, Δuv+Δdv, non-strange sea, Δu¯+Δd¯, and strange quarks, Δs (assumed to be equal to Δs¯). They have been obtained from the inclusive asymmetry A1,d and the semi-inclusive asymmetries A1,dπ+, A1,dπ−, A1,dK+, A1,dK− measured in polarised deep inelastic muon–deuteron scattering. The full deuteron statistics of COMPASS (years 2002–2004 and 2006) has been used. The data cover the range Q2>1(GeV/c)2 and 0.004<x<0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of Δs(x) is compatible with zero in the whole measured range, in contrast to the shape of the strange quark helicity distribution obtained in most LO and NLO QCD fits. The sensitivity of the values of Δs(x) upon the choice of fragmentation functions used in the derivation is discussed.