Tsallis nonextensive thermostatistics, Pauli principle and the structure of the Fermi surface

In connection with Tsallisʹ generalized statistical mechanics, we discuss the associated quantal distribution functions and show, by recourse to elementary considerations, that nonextensivity entails apparent violations to the Pauli principle. The typical zero temperature sharp Fermi surface is seen to be a limiting case in which the nonextensivity parameter achieves that value for which the Boltzmann-Gibbs statistics is recovered