Effects of jet quenching on the hydrodynamical evolution of quark-gluon plasma

TL;DR

It is shown that, for phenomenologically acceptable values of parton energy loss, conical flow effects are too weak to explain these structures in the azimuthal angle distribution.

Abstract

We study the effects of jet quenching on the hydrodynamical evolution of the quark-gluon plasma (QGP) fluid created in a heavy-ion collision. In jet quenching, a hard QCD parton, before fragmenting into a jet of hadrons, deposits a fraction of its energy in the medium, leading to suppressed production of high-pT hadrons. Assuming that the deposited energy quickly thermalizes, we simulate the subsequent hydrodynamic evolution of the QGP fluid. For partons moving at supersonic speed, v_p > c_s, and sufficiently large energy loss, a shock wave forms leading to conical flow [1]. The PHENIX Collaboration recently suggested that observed structures in the azimuthal angle distribution [2] might be caused by conical flow. We show here that conical flow produces different angular structures than predicted in [1] and that, for phenomenologically acceptable values of parton energy loss, conical flow effects are too weak to explain the structures seen by PHENIX [2].

Figures (3)

• Figure 1: Contours of constant local energy density in the $x$-$y$ plane at three different times, $\tau{\,=\,}4.6,$ 8.6, and 12.6 fm/$c$. In each case the position of the fast parton, along with the integrated energy loss $\Delta E=\int J(x) dxdy d\tau$ up to this point, is indicated at the top of the figure. Diagrams (a)-(c) in the left column were calculated with a reference energy loss $dE/dx|_0{\,=\,}14$ GeV/fm, those in the right column (panels (d)-(f)) with a 10 times larger value.
• Figure 2: As in Fig.\ref{['F1']} but for a parton moving at subsonic speed $v_\mathrm{jet}{\,=\,}0.2\,c$ (left column) and for a fast parton ($v_\mathrm{jet}{\,=\,}c$) which loses all its energy within the first 6.4 fm (right column).
• Figure 3: Azimuthal distribution $dN/dy d\phi$ of negative pions per unit rapidity. In the upper panel we integrate over all $p_T$ while the lower panel shows only pions with $p_T{\,>\,}1$ GeV/$c$. Different symbols refer to different parameters as indicated. For better visibility the $\phi$-independent rate in the absence of the quenching jet has been subtracted. Filled symbols show the realistic case $dE/dx|_0{\,=\,}14$ GeV/fm, enhanced by a factor 10 for visibility.