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

M. Alekseev, V. Yu 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, M. Bettinelli, R. Birsa, J. Bisplinghoff, P. Bordalo, F. Bradamante, A. BravarA. Bressan, G. Brona, E. Burtin, M. P. Bussa, A. Chapiro, M. Chiosso, S. U. Chung, A. Cicuttin, M. Colantoni, M. L. Crespo, S. Dalla Torre, T. Dafni, S. Das, S. S. Dasgupta, O. Yu Denisov, L. Dhara, V. Diaz, A. M. Dinkelbach, S. V. Donskov, N. Doshita, V. Duic, W. Dünnweber, A. Efremov, A. El Alaoui, P. D. Eversheim, W. Eyrich, M. Faessler, A. Ferrero, M. Finger, M. Finger, H. Fischer, C. Franco, J. M. 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, C. Heß, F. Hinterberger, N. Horikawa, Ch Höppner, N. d'Hose, C. Ilgner, S. Ishimoto, O. Ivanov, Yu Ivanshin, T. Iwata, R. Jahn, P. Jasinski, G. Jegou, R. Joosten, E. Kabuß, W. Käfer, D. Kang, B. Ketzer, G. V. Khaustov, Yu A. Khokhlov, J. Kiefer, Yu Kisselev, F. Klein, K. Klimaszewski, S. Koblitz, J. H. Koivuniemi, V. N. Kolosov, E. V. Komissarov, K. Kondo, K. Königsmann, R. Konopka, I. Konorov, V. F. Konstantinov, A. Korzenev, A. M. Kotzinian, O. Kouznetsov, K. Kowalik, M. Krämer, A. Kral, Z. V. Kroumchtein, R. Kuhn, F. Kunne, K. Kurek, J. M. Le Goff, A. A. Lednev, A. Lehmann, S. Levorato, J. Lichtenstadt, T. Liska, 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, S. Negrini, F. Nerling, S. Neubert, D. Neyret, V. I. Nikolaenko, A. G. Olshevsky, 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. A. Savin, G. Sbrizzai, P. Schiavon, C. Schill, L. Schmitt, W. Schröder, O. Yu Shevchenko, H. W. Siebert, L. Silva, L. Sinha, A. N. Sissakian, M. Slunecka, G. I. Smirnov, S. Sosio, F. Sozzi, A. Srnka, M. Stolarski, M. Sulc, R. Sulej, S. Takekawa, S. Tessaro, F. Tessarotto, A. Teufel, L. G. Tkatchev, G. Venugopal, M. Virius, N. V. Vlassov, A. Vossen, Q. Weitzel, K. Wenzl, R. Windmolders, W. Wiślicki, H. Wollny, K. Zaremba, M. Zavertyaev, E. Zemlyanichkina, M. Ziembicki, J. Zhao, N. Zhuravlev, A. Zvyagin

*Corresponding author for this work

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Abstract

We present a LO evaluation of helicity densities of valence, Δ u v + Δ d v, non-strange sea, Δ over(u, ̄) + Δ over(d, ̄), and strange quarks, Δs (assumed to be equal to Δ over(s, ̄)). They have been obtained from the inclusive asymmetry A 1, d and the semi-inclusive asymmetries A 1, d π +, A 1, d π -, A 1, d K +, A 1, d K - 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 Q 2 > 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 Δ s (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 Δ s (x) upon the choice of fragmentation functions used in the derivation is discussed.

Original languageEnglish
Pages (from-to)217-224
Number of pages8
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume680
Issue number3
DOIs
StatePublished - 28 Sep 2009

Keywords

  • COMPASS
  • Charged kaon asymmetry
  • Double-spin asymmetry
  • Flavour separation analysis
  • Helicity density
  • Parton distribution function
  • Polarised DIS and SIDIS reactions

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