Angular distributions of leptons from J-psi's produced in 920 GeV fixed-target proton-nucleus collisions - High Energy Physics - ExperimentReport as inadecuate




Angular distributions of leptons from J-psi's produced in 920 GeV fixed-target proton-nucleus collisions - High Energy Physics - Experiment - Download this document for free, or read online. Document in PDF available to download.

Abstract: A study of the angular distributions of leptons from decays of J-psi-sproduced in p-C and p-W collisions at sqrt{s}=41.6 GeV has been performed inthe Feynman-x region -0.34 < x F < 0.14 and for transverse momentum up to 5.4GeV-c. The data were collected by the HERA-B experiment at the HERA proton ringof the DESY laboratory. The results, based on a clean selection of 2.3 x 10^5J-psi-s reconstructed in both the e^+ e^- and mu^+ mu^- decay channels,indicate that J-psi-s are produced with longitudinal polarization. Themagnitude of the effect is maximal at low p T. For p T >1 GeV-c a significantdependence on the reference frame is found: the polar anisotropy is morepronounced in the Collins-Soper frame and almost vanishes in the helicityframe, where, instead, a significant azimuthal anisotropy arises.



Author: HERA-B Collaboration

Source: https://arxiv.org/







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