Eur. Phys. J. C 70, 39-49 (2010)
https://doi.org/10.1140/epjc/s10052-010-1461-9

Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons

¹ Fakultät für Physik, Universität Bielefeld, 33501, Bielefeld, Germany
² Institut für Experimentalphysik, Universität Bochum, 44780, Bochum, Germany
³ Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, 53115, Bonn, Germany
⁴ Physikalisches Institut, Universität Bonn, 53115, Bonn, Germany
⁵ Institute of Scientific Instruments, AS CR, 61264, Brno, Czech Republic
⁶ Matrivani Institute of Experimental Research & Education, Calcutta, 700 030, India
⁷ Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
⁸ Physikalisches Institut, Universität Erlangen–Nürnberg, 91054, Erlangen, Germany
⁹ Physikalisches Institut, Universität Freiburg, 79104, Freiburg, Germany
¹⁰ CERN, 1211, Geneva 23, Switzerland
¹¹ Technical University in Liberec, 46117, Liberec, Czech Republic
¹² LIP, 1000-149, Lisbon, Portugal
¹³ Institut für Kernphysik, Universität Mainz, 55099, Mainz, Germany
¹⁴ University of Miyazaki, Miyazaki, 889-2192, Japan
¹⁵ Lebedev Physical Institute, 119991, Moscow, Russia
¹⁶ Department für Physik, Ludwig-Maximilians-Universität München, 80799, Munich, Germany
¹⁷ Physik Department, Technische Universität München, 85748, Garching, Germany
¹⁸ Nagoya University, 464, Nagoya, Japan
¹⁹ Faculty of Mathematics and Physics, Charles University in Prague, 18000, Prague, Czech Republic
²⁰ Czech Technical University in Prague, 16636, Prague, Czech Republic
²¹ Institute for High Energy Physics, State Research Center of the Russian Federation, 142281, Protvino, Russia
²² CEA IRFU/SPhN Saclay, 91191, Gif-sur-Yvette, France
²³ School of Physics and Astronomy, Tel Aviv University, 69978, Tel Aviv, Israel
²⁴ Trieste Section of INFN, 34127, Trieste, Italy
²⁵ Department of Physics and Trieste Section of INFN, University of Trieste, 34127, Trieste, Italy
²⁶ Abdus Salam ICTP and Trieste Section of INFN, 34127, Trieste, Italy
²⁷ Department of Physics and Torino Section of INFN, University of Turin, 10125, Turin, Italy
²⁸ Torino Section of INFN, 10125, Turin, Italy
²⁹ 1500 Alessandria, and Torino Section of INFN, University of Eastern Piedmont, 10125, Turin, Italy
³⁰ Sołtan Institute for Nuclear Studies and University of Warsaw, 00-681, Warsaw, Poland
³¹ Institute of Radioelectronics, Warsaw University of Technology, 00-665, Warsaw, Poland
³² Yamagata University, Yamagata, 992-8510, Japan

Gerhard.Mallot@cern.ch

Received: 9 July 2010
Revised: 14 September 2010
Published online: 15 October 2010

Abstract

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 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.