Effects of Tsallis distribution on parametric resonance in chiral phase   transitions
  The parametric resonance was studied in chiral phase transitions when the momentum distribution is described by a Tsallis distribution. A Tsallis distribution has two parameters, the temperature $T$ and the entropic index $q$. The amplification was estimated in two cases: 1) expansionless case and 2) one dimensional expansion case. In an expansionless case, the temperature $T$ is constant, and the amplified modes as a function of $T$ were calculated for various $q$. In one dimensional expansion case, the temperature $T$ decreases as a function of the proper time, and the amplification as a function of the transverse momentum was calculated for various $q$. In the expansionless case, the following facts were found: 1) the larger the value $q$ is, the softer the amplified modes are for the first and second resonance bands, 2) the amplified mode of the first resonance band decreases and vanishes, as the temperature $T$ increases, and 3) the amplified mode of the second resonance band decreases and approaches to zero, as the temperature $T$ increases. In one dimensional expansion case, the following facts were found: 1) the soft mode is amplified, 2) the amplification is extremely strong around the amplified mode of the first resonance band at $T=0$, and 3) the magnitude of the amplification as a function of transverse momentum oscillates around the amplified mode of the first resonance band at $T=0$. 
Masamichi Ishihara
hep-ph