Leading-order anisotropic hydrodynamics for systems with massive   particles
  The framework of anisotropic hydrodynamics is generalized to include finite particle masses. Two schemes are introduced and their predictions compared with exact solutions of the kinetic equation in the relaxation time approximation. The first formulation uses the zeroth and first moments of the kinetic equation, whereas the second formulation uses the first and second moments. For the case of one-dimensional boost-invariant expansion, our numerical results indicate that the second formulation yields much better agreement with the exact solutions. 
Wojciech Florkowski, Radoslaw Ryblewski, Michael Strickland, and   Leonardo Tinti
hep-ph nucl-th