Signature reversal invariance Original Research Article

We consider the signature reversing transformation of the metric tensor image induced by the chiral transformation of the curved space gamma matrices image in spacetimes with signature image, which also induces a image spacetime orientation reversal. We conclude: (1) It is a symmetry only for chiral theories with image, with k integer. (2) Yang–Mills theories require dimensions image with T even for which even rank antisymmetric tensor field strengths and mass terms are also allowed. For example, image super-Yang–Mills is ruled out. (3) Gravitational theories require dimensions image with T odd, for which the symmetry is preserved by coupling to odd rank field strengths. In image, for example, it is a symmetry of image and type IIB supergravity but not type IIA. A cosmological term and also mass terms are forbidden but non-minimal image coupling is permitted. (4) Spontaneous compactification from image leads to interesting but different symmetries in lower dimensions such as image, so Yang–Mills terms, Kaluza–Klein masses and a cosmological constant may then appear. As a well-known example, IIB permits image.