Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/56366
Title: Angular distributions of leptons from J/ ψ's produced in 920 GeV fixed-target proton-nucleus collisions
Author: Conde, P.
Garrido Beltrán, Lluís
Peralta, D.
HERA-B Collaboration
Keywords: Astronomia
Astrofísica
Física nuclear
Partícules (Física nuclear)
Teoria quàntica de camps
Astronomy
Astrophysics
Nuclear physics
Particles (Nuclear physics)
Quantum field theory
Issue Date: 2009
Publisher: Società Italiana di Fisica & Springer Verlag
Abstract: A study of the angular distributions of leptons from decays of J/ψ"s produced in p-C and p-W collisions at s√=41.6~GeV has been performed in the J/ψ Feynman-x region −0.34<x F <0.14 and for J/ψ transverse momenta up to 5.4 GeV/c. The data were collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The results, based on a clean selection of 2.3×105 J/ψ"s reconstructed in both the e + e − and μ + μ − decay channels, indicate that J/ψ"s are produced polarized. The magnitude of the effect is maximal at low p T . For p T >1 GeV/c a significant dependence on the reference frame is found: the polar anisotropy is more pronounced in the Collins-Soper frame and almost vanishes in the helicity frame, where, instead, a significant azimuthal anisotropy arises.
Note: Reproduccció del document publicat a: http://doi.dx.org/ 10.1140/epjc/s10052-009-0957-7
It is part of: European Physical Journal C, 2009, vol. 60, num. 4, p. 517-524
Related resource: http://dx.doi.org/10.1140/epjc/s10052-009-0957-7
URI: http://hdl.handle.net/2445/56366
ISSN: 1434-6044
Appears in Collections:Articles publicats en revistes (Física Quàntica i Astrofísica)

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