Measurement of the inclusive J/ ψ polarization at forward rapidity in pp collisions at √s=8 TeV

ALICE Collaboration

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We report on the measurement of the inclusive J/ψ polarization parameters in pp collisions at a center of mass energy s=8 TeV with the ALICE detector at the LHC. The analysis is based on a data sample corresponding to an integrated luminosity of 1.23 pb- 1. J/ψ resonances are reconstructed in their di-muon decay channel in the rapidity interval 2.5 < y< 4.0 and over the transverse-momentum interval 2 < pT< 15 GeV / c. The three polarization parameters (λθ, λφ, λθ φ) are measured as a function of pT both in the helicity and Collins-Soper reference frames. The measured J/ψ polarization parameters are found to be compatible with zero within uncertainties, contrary to expectations from all available predictions. The results are compared with the measurement in pp collisions at s=7 TeV.

Original languageEnglish (US)
Article number562
JournalEuropean Physical Journal C
Issue number7
StatePublished - Jul 1 2018


All Science Journal Classification (ASJC) codes

  • Engineering (miscellaneous)
  • Physics and Astronomy (miscellaneous)

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