Speaker
Farid Taghinavaz
(Department of Physics, Sharif University of Technology)
Description
The shear viscosity of a hot and dense Yukawa-Fermi
gas will be determined, using the standard Green-Kubo relation, according to which the
shear viscosity is given by the retarded correlator of the traceless
part of viscous energy-momentum tensor. We approximate this retarded
correlator using a one-loop skeleton expansion, and express the
bosonic and fermionic shear viscosities, $\eta_{b}$ and $\eta_{f}$,
in terms of bosonic and fermionic spectral widths, $\Gamma_{b}$ and
$\Gamma_{\pm}$. Here, the subscripts $\pm$ correspond to normal and
collective (plasmino) excitations of fermions. We study, in
particular, the effect of these excitations on thermal properties of
$\eta_{f}[\Gamma_{\pm}]$. To do this, we determine first the
dependence of $\Gamma_{b}$ and $\Gamma_{\pm}$ on momentum $p$,
temperature $T$, chemical potential $\mu$ and $\xi_{0}\equiv
m_{b}^{0}/m_{f}^{0}$, in a one-loop perturbative expansion in the
orders of the Yukawa coupling. Here, $m_{b}^{0}$ and $m_{f}^{0}$ are
$T$ and $\mu$ independent bosonic and fermionic masses,
respectively. We then numerically determine $\eta_{b}[\Gamma_{b}]$
and $\eta_{f}[\Gamma_{\pm}]$, and study their thermal properties. It
turns out that whereas $\Gamma_{b}$ and $\Gamma_{+}$ decrease with
increasing $T$ or $\mu$, $\Gamma_{-}$ increases with increasing $T$
or $\mu$. This behavior qualitatively changes by adding thermal
corrections to $m_{b}^{0}$ and $m_{f}^{0}$, while the difference
between $\Gamma_{+}$ and $\Gamma_{-}$ keeps increasing with
increasing $T$ or $\mu$. Moreover, $\eta_{b}$ ($\eta_{f}$) increases
(decreases) with increasing $T$ or $\mu$. We show that the effect of
plasminos on $\eta_{f}$ becomes negligible with increasing
(decreasing) $T$ ($\mu$).
**Reference**
N. Sadooghi and F. Taghinavaz, *Contribution of plasminos to the shear viscosity of a hot and dense Yukawa-Fermi gas*, arXiv: 1404.1552, Accepted for publication in Phys. Rev. **D** (2014).
Summary
The contribution of plasmino modes to the shear viscosity of a Yukawa-Fermi gas will be investigated at finite temperature and chemical potential.
Author
Farid Taghinavaz
(Department of Physics, Sharif University of Technology)
Co-author
Dr
Neda Sadooghi
(Department of Physics, Sharif University of Technology)
