6533b829fe1ef96bd128a39c
RESEARCH PRODUCT
Instabilities in metric-affine theories of gravity with higher order curvature terms
Jose Beltrán JiménezAdrià Delhomsubject
PhysicsPhysics and Astronomy (miscellaneous)Field (physics)010308 nuclear & particles physicsAntisymmetric relationlcsh:AstrophysicsKinetic termCurvature01 natural sciencesSymmetry (physics)Connection (mathematics)Theoretical physics0103 physical sciencesMetric (mathematics)lcsh:QB460-466lcsh:QC770-798lcsh:Nuclear and particle physics. Atomic energy. Radioactivity010306 general physicsEngineering (miscellaneous)Ricci curvaturedescription
AbstractWe discuss the presence of ghostly instabilities for metric-affine theories constructed with higher order curvature terms. We mainly focus on theories containing only the Ricci tensor and show the crucial role played by the projective symmetry. The pathological modes arise from the absence of a pure kinetic term for the projective mode and the non-minimal coupling of a 2-form field contained in the connection, and which can be related to the antisymmetric part of the metric in non-symmetric gravity theories. The couplings to matter are considered at length and cannot be used to render the theories stable. We discuss different procedures to avoid the ghosts by adding additional constraints. We finally argue how these pathologies are expected to be present in general metric-affine theories unless much care is taken in their construction.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2020-06-01 |