Speakers
Amaresh Jaiswal
(Tata Institute of Fundamental Research)
Rajeev Bhalerao
(Tata Institute of Fundamental Research)
Sreekanth V.
(Tata Institute of Fundamental Research)
Subrata Pal
(Tata Institute of Fundamental Research)
Description
We derive relativistic viscous hydrodynamic equations for various
forms of the non-equilibrium single-particle phase-space distribution
function $f(x,p)$, and apply these results to relativistic heavy-ion
collisions at the RHIC and LHC energies.
In the first part of this work, we derive hydrodynamic equations
invoking the generalized second law of thermodynamics for two
different forms of $f(x,p)$ within Grad's 14-moment approximation. We
find that the relaxation times in these two derivations are identical
for shear viscosity but different for bulk viscosity. These equations
are used to study thermal dilepton and hadron spectra within
longitudinal scaling expansion of the matter formed in relativistic
heavy-ion collisions. For consistency, the same $f(x,p)$ is used in
the particle production prescription as in the derivation of the
viscous evolution equations. Appreciable differences are found in the
transverse-momentum spectra corresponding to the two forms of
$f(x,p)$. We emphasize that an inconsistent treatment of the
non-equilibrium effects influences the particle production
significantly, which may affect the extraction of transport properties
of quark-gluon plasma [1].
In the second part, we consider an alternative Chapman-Enskog-like
method, which unlike the widely used Grad's method, involves a small
expansion parameter. We derive an expression for $f(x,p)$ to second
order in this parameter. We show analytically that while Grad's method
leads to the violation of the experimentally observed $1/\sqrt{m_T}$
scaling of the longitudinal femtoscopic radii, the alternative method
does not exhibit such an unphysical behavior. We compare numerical
results for hadron transverse-momentum spectra and femtoscopic radii
obtained in these two methods, within the one-dimensional scaling
expansion scenario. Moreover, we demonstrate a rapid convergence of
the Chapman-Enskog-like expansion up to second order. This leads to an
expression for $\delta f(x,p)$ which provides a better alternative to
Grad's approximation for hydrodynamic modelling of relativistic
heavy-ion collisions [2].
[1] R.S. Bhalerao, A. Jaiswal, S. Pal, and V. Sreekanth, Phys. Rev. C88 (2013) 044911.
[2] R.S. Bhalerao, A. Jaiswal, S. Pal, and V. Sreekanth, e-Print: arXiv:1312.1864 [nucl-th].
Authors
Amaresh Jaiswal
(Tata Institute of Fundamental Research)
Rajeev Bhalerao
(Tata Institute of Fundamental Research)
Sreekanth V.
(Tata Institute of Fundamental Research)
Subrata Pal
(Tata Institute of Fundamental Research)
