Covariant description of kinetic freeze out through a finite time-like   layer
  The Freeze Out (FO) problem is addressed for a covariant FO probability and a finite FO layer with a time-like normal vector continuing the line of studies introduced in Ref. [1]. The resulting post FO momentum distribution functions are presented and discussed. We show that in general the post FO distributions are non-thermal and asymmetric distributions even for time-like FO situations. 
E. Molnar, L. P. Csernai, V. K. Magas, Zs. I. Lazar, A. Nyiri and K.   Tamosiunas