Sarmistha Banik, Rana Nandi, Debades Bandyopadhyay
We study shear viscosities of different species in hot and neutrino-trapped
dense matter relevant to protoneutron stars. It is found that the shear
viscosities of neutrons, protons and electrons in neutrino-trapped matter are
of the same orders of magnitude as the corresponding shear viscosities in
neutrino-free matter. Above all, the shear viscosity due to neutrinos is higher
by several orders of magnitude than that of other species in neutrino-trapped
matter.
Next we investigate the effect of shear viscosity in particular, neutrino
shear viscosity on the thermal nucleation rate of droplets of antikaon
condensed matter in protoneutron stars. The first-order phase transition from
hadronic matter to antikaon condensed matter is driven by the thermal
nucleation process. We compute the equation of state used for the calculation
of shear viscosity and thermal nucleation time within the relativistic mean
field model. Neutrino shear viscosity enhances the prefactor in the nucleation
rate by several orders of magnitude compared with the $T^4$ approximation of
earlier calculations. Consequently the thermal nucleation time in the $T^4$
approximation overestimates our result. Furthermore, the thermal nucleation of
an antikaon droplet might be possible in neutrino-trapped matter before
neutrino diffusion takes place.
View original:
http://arxiv.org/abs/1112.4586
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