We explore four-dimensional (4D) weakly coupled gravity beyond general relativity in an on-shell language, focusing on the graviton three-point vertex. This admits a novel structure which can be attributed to a term cubic in the Riemann tensor. We consider a generalization of the Shapiro time delay experiment that involves polarized gravitons and show that the new vertex leads to causality violation. Fixing the problem demands the inclusion of an infinite tower of massive higher spin states. Perturbative string theory provides an example of this phenomenon, the only known so far. Interestingly enough, the same argument being applied to inflation suggests that stringy signatures may be hidden in the non-Gaussianities of the primordial gravity wave spectrum. © 2015 World Scientific Publishing Company.
Documento: | Artículo |
Título: | Weakly coupled gravity beyond general relativity |
Autor: | Camanho, X.O.; Edelstein, J.D.; Zhiboedov, A. |
Filiación: | Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Golm, 14476, Germany Department of Physics, FCEN, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, 1428, Argentina Department of Particle Physics and IGFAE, Universidade de Santiago de Compostela, Santiago de Compostela, E-15782, Spain Center for the Fundamental Laws of Nature, Harvard University, Cambridge, MA 02138, United States |
Palabras clave: | Beyond general relativity; causality, gravity and string theory |
Año: | 2015 |
Volumen: | 24 |
Número: | 12 |
DOI: | http://dx.doi.org/10.1142/S0218271815440319 |
Título revista: | International Journal of Modern Physics D |
Título revista abreviado: | Int. J. Mod. Phys. D |
ISSN: | 02182718 |
Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_02182718_v24_n12_p_Camanho |