Lightlike hypersurfaces of Lorentzian manifolds with distinguished screen

We first study the properties of the lightlike mean curvature on a lightlike hypersurface in a Lorentzian manifold. Then, we show the existence of a large class of lightlike hypersurfaces admitting a distinguished screen and study some of their properties. In particular, we find integrability conditions for distinguished screen distributions and give applications in a spacetime which obeys the null energy condition.