Speaker
Description
We investigate effects of mini-jet propagation
on collective expansion of the quark gluon plasma (QGP)
and, based on this picture, reinterpret higher harmonics ($v_{n}$) data
in Pb+Pb collisions at the LHC energies.
In ultrarelativistic heavy ion collisions,
a large number of mini-jets are subject to traverse the QGP
and are expected to disturb its collective expansion
due to deposition of energy and momentum from them.
Thus, we focus on hydrodynamic responses to propagation
of a large number of mini-jets in the QGP.
We employ a QGP fluid + jet model [1,2]
to demonstrate the above idea.
We solve (3+1)-dimensional ideal hydrodynamic equations
with energy-momentum
source terms.
As an input, we generate partons by using an event generator PYTHIA
with switching off hadronization, combined with a Monte-Carlo version
of the Glauber model.
Instead of setting initial conditions
for hydrodynamic fields,
we make these partons propagate until hydrodynamic initial time and,
during this stage, they deposit
energy and momentum locally.
We suppose these deposited energy and momentum are quickly
equilibrated to form initial hydrodynamic fields.
Although this is rather phenomenological treatment of thermalization/equilibration,
this naturally generates not only initial fluctuations of geometry
but also those of velocity fields which are often neglected in
the conventional hydrodynamic analysis.
Subsequently we consider survived partons as mini-jets and
simulate hydrodynamic responses to mini-jet propagation.
We find mini-jet propagation
indeed causes sizable anisotropic flow in the QGP fluid.
This suggests conventional hydrodynamic interpretation of
flow data based solely on initial eccentricity
should be revisited by taking account of correction from mini-jet
propagation and initial random velocity fields.
References
[1] Y.Tachibana and T.Hirano,
``Momentum transport away from a jet in an expanding nuclear medium,''
Phys. Rev. C , no. 2, 021902 (2014)
[2] Y.Tachibana and T.Hirano,
``Interplay between Mach cone and radial expansion and its signal in $\gamma$-jet events,''
Phys. Rev. C , no. 5, 054907 (2016)
| Preferred Track | Collective Dynamics |
|---|---|
| Collaboration | Not applicable |
