Analysis of residual spectra and the monopole spectrum for 3 K blackbody   radiation by means of non-extensive thermostatistics
  We analyze residual spectra of 3 K blackbody radiation (CMB) using non-extensive thermostatistics with a parameter q-1. The limits of |q-1|<1.2x10^{-5} and the temperature fluctuation |delta T|<(1.6-4.3)x10^{-5} are smaller than those by Tsallis et al. Moreover, analyzing the monopole spectrum by a formula including the chemical potential mu, we obtain the limits |q-1|<2.3x10^{-5} and |mu|<1.6x10^{-4}. |q-1| is comparable with the Sunyaev-Zeldovich effect y. 
Minoru Biyajima and Takuya Mizoguchi
cond-mat.stat-mech astro-ph.CO hep-ph