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Title: J/ψ polarization in p + p collisions at √s = 200 GeV in STAR

The study report on a polarization measurement of inclusive J/ψ mesons in the di-electron decay channel at mid-rapidity at 2T<6 GeV/c in p+p collisions at √s = 200 GeV. Data were taken with the STAR detector at RHIC. The J/ψ polarization measurement should help to distinguish between different models of the J/ψ production mechanism since they predict different p T dependences of the J/ψ polarization. In this analysis, J/ψ polarization is studied in the helicity frame. The polarization parameter λ θ measured at RHIC becomes smaller towards high p T, indicating more longitudinal J/ψ polarization as p T increases. The result is compared with predictions of presently available models.
  1. AGH Univ. of Science and Technology, Cracow (Poland). et al.
Publication Date:
Grant/Contract Number:
AC02-06CH11357; NRF-2012004024
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 739; Journal Issue: C; Journal ID: ISSN 0370-2693
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; charmonia; polarization; spin alignment; STAR; RHIC
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1223123