Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons
Azimuthal asymmetries in semi-inclusive production of positive (h+) and negative hadrons (h-) have been measured by scattering 160 GeV muons off longitudinally polarised deuterons at CERN. The asymmetries were decomposed in several terms according to their expected modulation in the azimuthal angle φ of the outgoing hadron. Each term receives contributions from one or several spin and transverse-momentum-dependent parton distribution and fragmentation functions. The amplitudes of all φ-modulation terms of the hadron asymmetries integrated over the kinematic variables are found to be consistent with zero within statistical errors, while the constant terms are nonzero and equal for h+ and h- within the statistical errors. The dependencies of the φ-modulated terms versus the Bjorken momentum fraction x, the hadron fractional momentum z, and the hadron transverse momentum PTh were studied. The x dependence of the constant terms for both positive and negative hadrons is in agreement with the longitudinal double-spin hadron asymmetries, measured in semi-inclusive deep-inelastic scattering. The x dependence of the sin φ-modulation term is less pronounced than that in the corresponding HERMES data. All other dependencies of the φ-modulation amplitudes are consistent with zero within the statistical errors. © 2010 The Author(s).
Alekseev, MG; Alexakhin, VY; Alexandrov, Y; Alexeev, GD; Amoroso, A; Austregesilo, A; Badełek, B; Balestra, F; Barth, J; Baum, G; Bedfer, Y; Bernhard, J; Bertini, R; Bettinelli, M; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, F; Bravar, A; Bressan, A; Brona, G; Burtin, E; Bussa, MP; Chaberny, D; Chiosso, M; Chung, SU; Cicuttin, A; Colantoni, M; Crespo, ML; Dalla Torre, S; Das, S; Dasgupta, SS; Denisov, OY; Dhara, L; Diaz, V; Donskov, SV; Doshita, N; Duic, V; Dünnweber, W; Efremov, A; El Alaoui, A; Eversheim, PD; Eyrich, W; Faessler, M; Ferrero, A; Filin, A; Finger, M; Fischer, H; Franco, C; Friedrich, JM; Garfagnini, R; Gautheron, F; Gavrichtchouk, OP; Gazda, R; Gerassimov, S; Geyer, R; Giorgi, M; Gnesi, I; Gobbo, B; Goertz, S; Grabmüller, S; Grasso, A; Grube, B; Gushterski, R; Guskov, A; Haas, F; von Harrach, D; Hasegawa, T; Heinsius, FH; Herrmann, F; Heß, C; Hinterberger, F; Horikawa, N; Höppner, C; d'Hose, N; Ilgner, C; Ishimoto, S; Ivanov, O; Ivanshin, Y; Iwata, T; Jahn, R; Jasinski, P; Jegou, G; Joosten, R; Kabuß, E; Kang, D; Ketzer, B; Khaustov, GV; Khokhlov, YA; Kisselev, Y; Klein, F; Klimaszewski, K; Koblitz, S; Koivuniemi, JH; Kolosov, VN; Kondo, K; Königsmann, K; Konopka, R; Konorov, I
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