Transverse momentum dependence of J/psi polarization at midrapidity in p plus p collisions at root s=200 GeV
We report the measurement of the transverse momentum dependence of inclusive J/psi polarization in p + p collisions at root s = 200 GeV performed by the PHENIX Experiment at the Relativistic Heavy Ion Collider. The J/psi polarization is studied in the helicity, Gottfried-Jackson, and Collins-Soper frames for p(T) < 5 GeV/c and vertical bar y vertical bar < 0.35. The polarization in the helicity and Gottfried-Jackson frames is consistent with zero for all transverse momenta, with a slight (1.8 sigma) trend towards longitudinal polarization for transverse momenta above 2 GeV/c. No conclusion is allowed due to the limited acceptance in the Collins-Soper frame and the uncertainties of the current data. The results are compared to observations for other collision systems and center of mass energies and to different quarkonia production models.
This article is published as Adare, A., S. Afanasiev, C. Aidala, N. N. Ajitanand, Yasuyuki Akiba, H. Al-Bataineh, J. Alexander et al. "Transverse momentum dependence of J/ψ polarization at midrapidity in p+ p collisions at s= 200 GeV." Physical Review D 82, no. 1 (2010): 012001. DOI:10.1103/PhysRevD.82.012001. Posted with permission.