and soft modes is implemented through a nonabelian transport equation [@Heinz; @HeinzPRL] which determines the evolution of a one-particle distribution function $\mathbf{f}$, which is a matrix in color space (see Section \[kin\]), or equivalently through Wong’s equations [@wong]; see also Refs. [@libro; @elze; @Litim; @winter; @revBlaizot; @BlaizotIancu; @BraPis90a; @FreTay90; @Bod98; @Bod99; @ArSoYa99a; @ArSoYa99b]. Once $\mathbf{f}$ is known, the color current acting as the source in Yang-Mills equation is completely determined, so the dynamics of the gauge fields can be found.

Here, we take the view that it is a reasonable hypothesis to assume that the dynamics of the conserved currents is [*largely*]{} determined by the conservation laws themselves. This opens up the possibility of constructing an effective theory incorporating the conservation laws, that allows one to investigate relevant aspects of the dynamics of gauge fields (for example, the border between stability and instability, or the back reaction of hard particles on the evolution of color fields) in a simpler context as compared to the microscopic theory.

The degrees of freedom of the effective theory include hydrodynamic variables such as flow velocity. However, since we are working in a strongly out of equilibrium regime, it is not possible to obtain a 