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

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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, λθφ) 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.


External organisations
  • Panjab University
  • Variable Energy Cyclotron Centre
  • Korea Advanced Institute of Science and Technology (KAIST)
  • Utrecht University
  • University of Copenhagen
  • Central China Normal University (CCNU)
  • University of California, Berkeley
  • Nuclear Physics Institute, ASCR
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Sciences
Original languageEnglish
Article number562
JournalEuropean Physical Journal C
Issue number7
Publication statusPublished - 2018
Publication categoryResearch

Bibliographic note

The authors listed here are only a few of all authors. For information about all authors of the publication, please see the original publication.