# Elliptic Flow of Heavy Quarkonia in $pA$ Collisions

Zhang, Cheng (Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079, China) ; Marquet, Cyrille (CPHT, École Polytechnique, CNRS, Université Paris-Saclay, F-91128 Palaiseau, France) ; Qin, Guang-You (Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079, China) ; Wei, Shu-Yi (CPHT, École Polytechnique, CNRS, Université Paris-Saclay, F-91128 Palaiseau, France) ; Xiao, Bo-Wen (Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079, China) (CPHT, École Polytechnique, CNRS, Université Paris-Saclay, F-91128 Palaiseau, France)

03 May 2019

Abstract: Using the dilute-dense factorization in the color glass condensate framework, we investigate the azimuthal angular correlation between a heavy quarkonium and a charged light hadron in proton-nucleus collisions. We extract the second harmonic ${v}_{2}$, commonly known as the elliptic flow, with the light hadron as the reference. This particular azimuthal angular correlation between a heavy meson and a light hadron was first measured at the LHC recently. The experimental results indicate that the elliptic flows for heavy flavor mesons ($J/\psi$ and ${D}^{0}$) are almost as large as those for light hadrons. Our calculation demonstrates that this result can be naturally interpreted as an initial state effect due to the interaction between the incoming partons from the proton and the dense gluons inside the target nucleus. Since the heavy quarkonium ${v}_{2}$ exhibits a weak mass dependence according to our calculation, we predict that the heavy quarkonium $\Upsilon$ should have a similar elliptic flow as compared to that of the $J/\psi$, which can be tested in future measurements.

Published in: Physical Review Letters 122 (2019)
Published by: APS
DOI: 10.1103/PhysRevLett.122.172302
arXiv: 1901.10320
License: CC-BY-4.0

Fulltext:
XML PDF