Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

E. S. Ageev, V. Yu Alexakhin, Yu Alexandrov, G. D. Alexeev, A. Amoroso, B. Badelek, F. Balestra, J. Ball, G. Baum, Y. Bedfer, P. Berglund, C. Bernet, R. Bertini, R. Birsa, J. Bisplinghoff, P. Bordalo, F. Bradamante, A. Bravar, A. Bressan, G. BronaE. Burtin, M. P. Bussa, V. N. Bytchkov, L. Cerini, A. Chapiro, A. Cicuttin, M. Colantoni, A. A. Colavita, S. Costa, M. L. Crespo, S. Dalla Torre, S. S. Dasgupta, N. Dedek, R. De Masi, O. Yu Denisov, L. Dhara, V. Diaz, A. M. Dinkelbach, A. V. Dolgopolov, S. V. Donskov, V. A. Dorofeev, N. Doshita, V. Duic, W. Dünnweber, J. Ehlers, P. D. Eversheim, W. Eyrich, M. Fabro, M. Faessler, V. Falaleev, P. Fauland, A. Ferrero, L. Ferrero, M. Finger, M. Finger, H. Fischer, J. Franz, J. M. Friedrich, V. Frolov, R. Garfagnini, F. Gautheron, O. P. Gavrichtchouk, S. Gerassimov, R. Geyer, M. Giorgi, B. Gobbo, S. Goertz, A. M. Gorin, O. A. Grajek, A. Grasso, B. Grube, A. Grünemaier, J. Hannappel, D. Von Harrach, T. Hasegawa, S. Hedicke, F. H. Heinsius, R. Hermann, C. Heß, F. Hinterberger, M. Von Hodenberg, N. Horikawa, S. Horikawa, N. D'Hose, R. B. Ijaduola, C. Ilgner, A. I. Ioukaev, S. Ishimoto, O. Ivanov, T. Iwata, R. Jahn, A. Janata, R. Joosten, N. I. Jouravlev, E. Kabuß, V. Kalinnikov, D. Kang, F. Karstens, W. Kastaun, B. Ketzer, G. V. Khaustov, Yu A. Khokhlov, N. V. Khomutov, Yu Kisselev, F. Klein, S. Koblitz, J. H. Koivuniemi, V. N. Kolosov, E. V. Komissarov, K. Kondo, K. Königsmann, A. K. Konoplyannikov, I. Konorov, V. F. Konstantinov, A. S. Korentchenko, A. Korzenev, A. M. Kotzinian, N. A. Koutchinski, K. Kowalik, N. P. Kravchuk, G. V. Krivokhizhin, Z. V. Kroumchtein, R. Kuhn, F. Kunne, K. Kurek, M. E. Ladygin, M. Lamanna, M. Leberig, J. M. Le Goff, J. Lichtenstadt, T. Liska, I. Ludwig, A. Maggiora, M. Maggiora, A. Magnon, G. K. Mallot, I. V. Manuilov, C. Marchand, J. Marroncle, A. Martin, J. Marzec, T. Matsuda, A. N. Maximov, K. S. Medved, W. Meyer, A. Mielech, Yu V. Mikhailov, M. A. Moinester, O. Nähle, J. Nassalski, S. Neliba, D. P. Neyret, V. I. Nikolaenko, A. A. Nozdrin, V. F. Obraztsov, A. G. Olshevsky, M. Ostrick, A. Padee, P. Pagano, S. Panebianco, D. Panzieri, S. Paul, H. D. Pereira, D. V. Peshekhonov, V. D. Peshekhonov, G. Piragino, S. Platchkov, K. Platzer, J. Pochodzalla, V. A. Polyakov, A. A. Popov, J. Pretz, S. Procureur, C. Quintans, S. Ramos, P. C. Rebourgeard, G. Reicherz, J. Reymann, K. Rith, E. Rondio, A. M. Rozhdestvensky, A. B. Sadovski, E. Saller, V. D. Samoylenko, A. Sandacz, M. Sans, M. G. Sapozhnikov, I. A. Savin, P. Schiavon, C. Schill, T. Schmidt, H. Schmitt, L. Schmitt, O. Yu Shevchenko, A. A. Shishkin, H. W. Siebert, L. Sinha, A. N. Sissakian, A. Skachkova, M. Slunecka, G. I. Smirnov, F. Sozzi, A. Srnka, F. Stinzing, M. Stolarski, V. P. Sugonyaev, M. Sulc, R. Sulej, N. Takabayashi, V. V. Tchalishev, F. Tessarotto, A. Teufel, D. Thers, L. G. Tkatchev, T. Toeda, V. I. Tretyak, S. Trousov, M. Varanda, M. Virius, N. V. Vlassov, M. Wagner, R. Webb, E. Weise, Q. Weitzel, U. Wiedner, M. Wiesmann, R. Windmolders, S. Wirth, W. Wiślicki, A. M. Zanetti, K. Zaremba, J. Zhao, R. Ziegler, A. Zvyagin

Research output: Contribution to journalArticlepeer-review

Abstract

We present a determination of the gluon polarization ΔG/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q2<1 (GeV/c)2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6LiD target. The helicity asymmetry for the selected events is 〈A∥/D〉=0.002±0.019(stat)±0.003(syst). From this value, we obtain in a leading-order QCD analysis ΔG/G=0.024±0. 089(stat)±0.057(syst) at xg=0.095 and μ2≃3 (GeV/c)2.

Original languageEnglish
Pages (from-to)25-32
Number of pages8
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume633
Issue number1
DOIs
StatePublished - 2 Feb 2006

Keywords

  • Asymmetry
  • Deep inelastic scattering
  • Gluon
  • Nucleon
  • Polarization
  • Spin

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