2 research outputs found
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