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

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12 Scopus citations


We report on a polarization measurement of inclusive J/ψ mesons in the di-electron decay channel at mid-rapidity at 2 < pT < 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 the different models of the J/ψ production mechanism since they predict different pT dependences of the J/ψ polarization. In this analysis, J/ψ polarization is studied in the helicity frame. The polarization parameter λθ measured at RHIC becomes smaller towards high pT , indicating more longitudinal J/ψ polarization as pT increases. The result is compared with predictions of presently available models.

Original languageEnglish
Pages (from-to)180-188
Number of pages9
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
StatePublished - Dec 2 2014

Bibliographical note

Publisher Copyright:
© 2014 The Authors.


  • Charmonia
  • Polarization
  • RHIC
  • STAR
  • Spin alignment

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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