The PHENIX experiment has measured the spin alignment for inclusive $J/\psi \to e^{+}{e}^{-}$ decays in proton-proton collisions at $\sqrt{s}=510\mathrm{GeV}$ at midrapidity. The angular distributions have been measured in three different polarization frames, and the three decay angular coefficients have been extracted in a full two-dimensional analysis. Previously, PHENIX saw large longitudinal net polarization at forward rapidity at the same collision energy. This analysis at midrapidity, complementary to the previous PHENIX results, sees no sizable polarization in the measured transverse momentum range of $0.0<p_T<10.0\mathrm{GeV}/c$. The results are consistent with a previous one-dimensional analysis at midrapidity at $\sqrt{s}=200\mathrm{GeV}$. The transverse-momentum-dependent cross section for midrapidity $J/\psi$ production has additionally been measured, and after comparison to world data, a simple logarithmic dependence of the cross section on $\sqrt{s}$ was found.

• Received 2 June 2020
• Accepted 22 September 2020
• Corrected 4 November 2020

DOI:https://doi.org/10.1103/PhysRevD.102.072008

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

Published by the American Physical Society