Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shear viscosity of pion gas due to $\rho\pi\pi$ and $\sigma\pi\pi$
  interactions   We have evaluated the shear viscosity of pion gas taking into account its
scattering with the low mass resonances, $\sigma$ and $\rho$ during propagation
in the medium. The thermal width (or collisional rate) of the pions is
calculated from $\pi\sigma$ and $\pi\rho$ loop diagrams using effective
interactions in the real time formulation of finite temperature field theory. A
very small value of shear viscosity by entropy density ratio ($\eta/s$), close
to the KSS bound, is obtained which approximately matches the range of values
of $\eta/s$ used by Niemi et al. \cite{Niemi} in order to fit the RHIC data of
elliptic flow.

22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs