Title: Critical behavior of directed percolation process 
       in the presence of compressible velocity field

Abstract: 
Various systems exhibit universal behavior at the critical point. 
A typical example of the non-equilibrium critical behavior is the 
direct bond percolation that exhibits an active-to-absorbing state 
phase transition in the vicinity of critical percolation probability. 
An interesting question is how the turbulent mixing influences its 
critical behavior. In this work we assume that the turbulent mixing is 
generated by the compressible Navier-Stokes equation where the 
compressibility is described by an additional field related to the density. 
Using field theoretical models and renormalization group methods we 
investigate large scale and long time behavior.