Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions
| dc.creator | B Collaboration | |
| dc.date | 2009-01-08 | |
| dc.date.accessioned | 2026-07-07T13:07:43Z | |
| dc.date.available | 2026-07-07T13:07:43Z | |
| dc.description | A study of the angular distributions of leptons from decays of J/psi's produced in p-C and p-W collisions at sqrt{s}=41.6 GeV has been performed in the Feynman-x region -0.34 < x_F < 0.14 and for transverse momentum 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 x 10^5 J/psi's reconstructed in both the e^+ e^- and mu^+ mu^- decay channels, indicate that J/psi's are produced with longitudinal polarization. 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. | |
| dc.description | 9 pages, 3 figures, 8 tables | |
| dc.identifier | https://arxiv.org/abs/0901.1015 | |
| dc.identifier | http://arxiv.org/abs/0901.1015 | |
| dc.identifier | Eur.Phys.J.C60:517-524,2009 | |
| dc.identifier | doi:10.1140/epjc/s10052-009-0957-7 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/228182 | |
| dc.subject | High Energy Physics - Experiment | |
| dc.title | Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions | |
| dc.type | text |