123 research outputs found
Impact of temperature dependence of the energy loss on jet quenching observables
The quenching of jets (particles with ) in
ultra-relativistic heavy-ion collisions has been one of the main prediction and
discovery at RHIC. We have studied, by a simple jet quenching modeling, the
correlation between different observables like the nuclear modification factor
\Rapt, the elliptic flow and the ratio of quark to gluon suppression
. We show that the relation among these
observables is strongly affected by the temperature dependence of the energy
loss. In particular the large and and the nearly equal \Rapt of quarks
and gluons can be accounted for only if the energy loss occurs mainly around
the temperature and the flavour conversion is significant.Finally we
point out that the efficency in the conversion of the space eccentricity into
the momentum one () results to be quite smaller respect to the one coming
from elastic scatterings in a fluid with a viscosity to entropy density ratio
.Comment: 7 pages, 8 figures, Workshop WISH 201
Elliptic Flow from Non-equilibrium Initial Condition with a Saturation Scale
A current goal of relativistic heavy ion collisions experiments is the search
for a Color Glass Condensate as the limiting state of QCD matter at very high
density. In viscous hydrodynamics simulations, a standard Glauber initial
condition leads to estimate , while a Color Glass
Condensate modeling leads to at least a factor of 2 larger . Within a
kinetic theory approach based on a relativistic Boltzmann-like transport
simulation, we point out that the out-of-equilibrium initial distribution
proper of a Color Glass Condensate reduces the efficiency in building-up the
elliptic flow. Our main result at RHIC energy is that the available data on
are in agreement with a also for Color Glass
Condensate initial conditions, opening the possibility to describe
self-consistently also higher order flow, otherwise significantly
underestimated, and to pursue further the search for signatures of the Color
Glass Condensate.Comment: 6 pages, 4 figures. // Title changed, some discussion added, main
conclusions unchanged. Version accepted for publication on Phys. Lett.
Shear viscosity and chemical equilibration of the QGP
We have investigated, in the frame work of the transport approach, different
aspects of the QGP created in Heavy Ion Collisions at RHIC and LHC energies.
The shear viscosity has been calculated by using the Green-Kubo relation
at the cascade level. We have compared the numerical results for
obtained from the Green-Kubo correlator with the analytical formula in both the
Relaxation Time Approximation (RTA) and the Chapman-Enskog approximation (CE).
From this comparison we show that in the range of temperature explored in a
Heavy Ion collision the RTA underestimates the viscosity by about a factor of
2, while a good agreement is found between the CE approximation and Gree-Kubo
relation already at first order of approximation. The agreement with the CE
approximation supplies an analytical formula that allows to develop kinetic
transport theory at fixed shear viscosity to entropy density ratio, .
We show some results for the build up of anisotropic flows in a
transport approach at fixed shear viscosity to entropy density ratio, .
We study the impact of a T-dependent on the generation of the
elliptic flows at both RHIC and LHC. We show that the transport approach
provides, in a unified way, a tool able to naturally describe the
in a wide range of , including also the description of
the rise and fall and saturation of the observed at LHC.
Finally, we have studied the evolution of the quark-gluon composition employing
a Boltzmann-Vlasov transport approach that include: the mean fields dynamics,
associated to the quasi-particle model, and the elastic and inelastic
collisions for massive quarks and gluons. Following the chemical evolution from
an initial gluon dominated plasma we predict a quark dominance close to
paving the way to an hadronization via quark coalescence.Comment: 15 pages, 10 figures, Invited Talk given by S. Plumari at the 11th
International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio,
Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in
Journal of Physics: Conference Series (JPCS
Anisotropic flows and shear viscosity of the Quark-Gluon plasma within a transport approach
In this talk we discuss the build up of elliptic flow v2 and high order harmonics v3, v4 and v5 for a fluid at fixed η/s by mean of an event-by-event transport approach. We discuss the effect of the η/s ratio on the build up of the vn(pT). In particular we study the effect of a temperature dependent η/s for two different beam energies: RHIC for Au+Au at p s = 200GeV and LHC for Pb+ Pb at p s = 2.76 TeV. We find that for the two different beam energies considered t he suppression of the vn(pT) due to the viscosity of the medium have different contributions coming from the cross over or QGP phase. In ultra-central collisions the vn(pT) show a strong sensitivity to the η/s ratio in the QGP phase and this sensitivity increase with the increase of the order of the harmonic
The elliptic flow and the shear viscosity of the QGP within a kinetic approach
We use a relativistic transport approach to study the role of a temperature dependent shear viscosity to entropy density ratio, η/s(T), on the build-up of the elliptic flow, v2. The recent results from = 62.4GeV at RHIC up to 2.76 TeV at LHC have shown an intriguing property of the v2(pT), which appears to be nearly invariant with energy. We show that in our transport approach this surprising behavior can be described by a particular temperature dependence of η/s(T), typical of matter that undergoes a phase transition or a cross-over, with a rise and fall and the minimum close to critical temperature Tc
Air Traffic Management Technology Demonstration-1 Concept of Operations (ATD-1 ConOps), Version 3.0
This document describes the goals, benefits, technologies, and procedures of the Concept of Operations (ConOps) for the Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1), and provides an update to the previous versions of the document [ref 1 and ref 2]
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