2 research outputs found
Thermal photons in QGP and non-ideal effects
We investigate the thermal photon production-rates using one dimensional
boost-invariant second order relativistic hydrodynamics to find proper time
evolution of the energy density and the temperature. The effect of
bulk-viscosity and non-ideal equation of state are taken into account in a
manner consistent with recent lattice QCD estimates. It is shown that the
\textit{non-ideal} gas equation of state i.e behaviour
of the expanding plasma, which is important near the phase-transition point,
can significantly slow down the hydrodynamic expansion and thereby increase the
photon production-rates. Inclusion of the bulk viscosity may also have similar
effect on the hydrodynamic evolution. However the effect of bulk viscosity is
shown to be significantly lower than the \textit{non-ideal} gas equation of
state. We also analyze the interesting phenomenon of bulk viscosity induced
cavitation making the hydrodynamical description invalid. We include the
viscous corrections to the distribution functions while calculating the photon
spectra. It is shown that ignoring the cavitation phenomenon can lead to
erroneous estimation of the photon flux.Comment: 11 pages, 13 figures; accepted for publication in JHE
Flow in heavy-ion collisions - Theory Perspective
I review recent developments in the field of relativistic hydrodynamics and
its application to the bulk dynamics in heavy-ion collisions at the
Relativistic Heavy- Ion Collider (RHIC) and the Large Hadron Collider (LHC). In
particular, I report on progress in going beyond second order relativistic
viscous hydrodynamics for conformal fluids, including temperature dependent
shear viscosity to entropy density ratios, as well as coupling hydrodynamic
calculations to microscopic hadronic rescattering models. I describe
event-by-event hydrodynamic simulations and their ability to compute higher
harmonic flow coefficients. Combined comparisons of all harmonics to recent
experimental data from both RHIC and LHC will potentially allow to determine
the desired details of the initial state and the medium properties of the
quark-gluon plasma produced in heavy-ion collisions.Comment: 8 pages, Invited plenary talk at the 22nd International Conference on
Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2011), May 23-28
2011, Annecy, Franc