“…One method of renormalization is covariant geodesic point separation, in which the two operators whose products are taken are evaluated at different space-time points x and x ′ , yielding a finite bitensor stress-energy tensor, whose expectation value is written Tµν (x, x ′ ). This expectation value is renormalized by the subtraction of purely geometric, state independent renormalization terms T div µν (x, x ′ ) (see for example [48,49] for expressions for these geometric terms for fields of spin 0, 1/2 and 1 in four dimensions, and [50] for a scalar field in higher-dimensional spacetime). The points x and x ′ are then brought together and a finite renormalized expectation value for the stress-energy tensor is yielded.…”