Negative Elliptic Flow of $J/\psi$'s: A Qualitative Signature for Charm Collectivity at RHIC

Abstract

We discuss one of the most prominent features of the very recent preliminary elliptic flow data of $J/\Psi$ meson from the PHENIX collaboration \cite{Silvestre:2008tw}. Even within the the rather large error bars of the measured data a negative elliptic flow parameter ($v_2$) for $J/\Psi$ in the range of $p_T=0.5-2.5 \GeV/c$ is visible. We argue that this negative elliptic flow at intermediate $p_T$ is a clear and qualitative signature for the collectivity of charm quarks produced in nucleus-nucleus reactions at RHIC. Within a parton recombination approach we show that a negative elliptic flow puts a lower limit on the collective transverse velocity of heavy quarks. The numerical value of the transverse flow velocity ${\beta }_T$ for charm quarks that is necessary to reproduce the data is ${\beta }_T(charm)\sim 0.55-0.6c$ and therefore compatible with the flow of light quarks.

4 pages, 3 figures; to be published in EPJ A; Changes: Added B-meson elliptic flow and data on non-photonic electron v_2 to Fig. 2; Added a plot showing the quark v_2; Added discussion about D^0 flow

Cited by in corpus (1)

• Collective phenomena in non-central nuclear collisions