%0 Journal Article %T An invariant theory of marginally trapped surfaces in the four-dimensional Minkowski space %A Georgi Ganchev %A Velichka Milousheva %J Mathematics %D 2011 %I arXiv %R 10.1063/1.3693976 %X A marginally trapped surface in the four-dimensional Minkowski space is a spacelike surface whose mean curvature vector is lightlike at each point. We associate a geometrically determined moving frame field to such a surface and using the derivative formulas for this frame field we obtain seven invariant functions. Our main theorem states that these seven invariants determine the surface up to a motion in Minkowski space. We introduce meridian surfaces as one-parameter systems of meridians of a rotational hypersurface in the four-dimensional Minkowski space. We find all marginally trapped meridian surfaces. %U http://arxiv.org/abs/1105.3370v1