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

Summary, in English

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.

• Author: S Acharya; F. T. Acosta; D. Adamova; Jonatan Adolfsson; M. M. Aggarwal; Z. Ahammed; S. U. Ahn; Peter Christiansen; Martin Ljunggren; Adrian Nassirpour; Anders Oskarsson; Tuva Richert; David Silvermyr; Evert Stenlund; Vytautas Vislavicius; S. Zou
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration
• Publishing year: 2018
• Language: English
• Publication/Series: European Physical Journal C
• Volume: 78
• Issue: 7
• Links: http://dx.doi.org/10.1140/epjc/s10052-018-6027-2
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1434-6044