Polytropic equation of state and primordial quantum fluctuations
  We study the primordial Universe in a cosmological model where inflation is
driven by a fluid with a polytropic equation of state $p = \alpha\rho +
k\rho^{1 + 1/n}$. We calculate the dynamics of the scalar factor and build a
Universe with constant density at the origin. We also find the equivalent
scalar field that could create such equation of state and calculate the
corresponding slow-roll parameters. We calculate the scalar perturbations, the
scalar power spectrum and the spectral index.
