What do gravitons say about (unimodular) gravity?
- 33 Downloads
We revisit the problem of constraining the weak field limit of the gravitational lagrangian from S-matrix properties. From unitarity and Lorentz invariance of the S-matrix of massless gravitons, we derive on-shell gauge invariance to consist on the transverse part of the linearised diffeomorphisms group. Moreover, by looking to the interaction between sources, we conclude that there exist only two possible lagrangians that lead to a welldefined covariant interaction, corresponding to the weak field limits of General Relativity and Unimodular Gravity. Additionally, this result confirms the equivalence of the S-matrix of both theories around flat space-time.
KeywordsClassical Theories of Gravity Gauge Symmetry Models of Quantum Gravity
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
- A. Einstein, Do gravitational fields play an essential part in the structure of the elementary particles of matter? (in German), Sitzungsber. Preuss. Akad. Wiss. Berlin 1919 (1919) 349 [INSPIRE].
- W.G. Unruh, A Unimodular Theory of Canonical Quantum Gravity, Phys. Rev. D 40 (1989) 1048 [INSPIRE].
- M. Henneaux and C. Teitelboim, The Cosmological Constant and General Covariance, Phys. Lett. B 222 (1989) 195 [INSPIRE].
- W. Buchmüller and N. Dragon, Einstein Gravity From Restricted Coordinate Invariance, Phys. Lett. B 207 (1988) 292 [INSPIRE].
- J.J. van der Bij, H. van Dam and Y.J. Ng, The Exchange of Massless Spin Two Particles, Physica A 116 (1982) 307 [INSPIRE].