On the stress–energy tensor of a null shell in Einstein–Cartan gravity

Abstract

The stress–energy tensor of a matter shell whose history coincides with a null hypersurface in the Einstein–Cartan gravity is revisited. It is demonstrated that with a proper choice for the torsion discontinuity taken to be orthogonal to the null hypersurface and consistent with the antisymmetric property of torsion tensor, the modified expression for the asymmetric stress–energy tensor is automatically tangent to the hypersurface. The main differences with respect to a previous work are addressed.