Transverse momentum dependence of J/psi polarization at midrapidity in p+p collisions at sqrt(s)=200 GeV

TL;DR

This study measures how the polarization of J/psi particles produced in proton-proton collisions varies with transverse momentum, providing insights into quarkonium production mechanisms at RHIC energies.

Contribution

It presents the first detailed measurement of J/psi polarization dependence on transverse momentum at 200 GeV in p+p collisions, comparing results across different polarization frames.

Findings

J/psi polarization is consistent with zero in most frames and momenta.

A slight trend towards longitudinal polarization above 2 GeV/c.

Limited data prevents definitive conclusions in some frames.

Abstract

We report the measurement of the transverse momentum dependence of inclusive J/psi polarization in p+p collisions at sqrt(s)=200 GeV performed by the PHENIX Experiment at RHIC. The polarization is studied in the helicity, Gottfried-Jackson, and Collins-Soper frames for p_T < 5 GeV/c and |y| < 0.35. The J/psi 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.