Einstein Hypersurfaces of Sn X R and Hn X R

In this paper, we classify the Einstein hypersurfaces of S-n x R and H-n x R. We use the characterization of the hypersurfaces of S-n x R and H-n x R whose tangent component of the unit vector field spanning the factor R is a principal direction and the theory of isoparametric hypersurfaces of space forms to show that Einstein hypersurfaces of S-n x R and H-n x R must have constant sectional curvature.