0439720 - ÚJF 2015 RIV NL eng J - Journal Article
Adamczyk, L. - Barnovská, Zuzana - Bielčík, J. - Bielčíková, Jana - Chaloupka, P. - Hajková, O. - Pachr, M. - Rusňák, Jan - Šumbera, Michal - Tlustý, David - Vértési, Robert … Total 358 authors
J/psi polarization in p plus p collisions at root s=200 GeV in STAR.
Physics Letters. B. Roč. 739, DEC (2014), s. 180-188. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA ČR GA13-20841S
Institutional support: RVO:61389005
Keywords : charmonia * polarization * spin alignment
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders
Impact factor: 6.131, year: 2014 ; AIS: 1.52, rok: 2014
DOI: https://doi.org/10.1016/j.physletb.2014.10.049

e report on a polarization measurement of inclusive J/psi mesons in the di-electron decay channel at mid-rapidity at 2 < p(T) < 6 GeV/c in p + p collisions at root s = 200 GeV. Data were taken with the STAR detector at RHIC. The J/psi polarization measurement should help to distinguish between different models of the J/psi production mechanism since they predict different p(T) dependences of the J/psi polarization. In this analysis, J/psi is studied in the helicity frame. The polarization parameter lambda(theta) measured at RHIC becomes smaller towards high p(T), indicating more longitudinal J/psi polarization as p(T) increases. The result is compared with predictions of presently available models.
Permanent Link: http://hdl.handle.net/11104/0242941