General Relativity and Quantum Cosmology
[2306.15453] Spherical particle orbits around a rotating black hole in massive gravity
https://arxiv.org/abs/2306.15453
In this paper, we present a rotating de Rham-Gabadadze-Tolley black hole with a positive cosmological constant in massive gravity, achieved by applying a modified Newman-Janis algorithm. The black hole exhibits stable orbits of constant radii, prompting a numerical study on the behavior of the solutions to a nonic equation governing the radii of planar orbits around the black hole. Additionally, we investigate the stability of orbits near the event horizon and provide a comprehensive analytical examination of the solutions to the angular equations of motion. This is followed by simulating some spherical particle orbits around the black hole.
☆
[2306.13134] Coupling Metric-Affine Gravity to the Standard Model and Dark Matter Fermions
https://arxiv.org/abs/2306.13134
General Relativity (GR) exists in different formulations, which are equivalent in pure gravity. Once matter is included, however, observable predictions generically depend on the version of GR. In order to quantify the resulting ambiguity, we employ metric-affine gravity, which encompasses as special cases the metric, Palatini, Einstein-Cartan and Weyl formulations. We first discuss the interaction of fermions with torsion and non-metricity, also commenting on projective symmetry. With a view towards the Standard Model, we then construct a generic model of (complex) scalar, fermionic and gauge fields coupled to GR and derive an equivalent metric theory, which features numerous new interaction terms. As a first observable consequence, we point out that a gravitational mechanism for producing dark matter in the form of singlet fermions can be used to distinguish between metric gravity and other formulations of GR.
[2306.16746] Note About Canonical Formalism for Gravity with Dynamical Determinant of Metric
https://arxiv.org/abs/2306.16746
In this short note we perform canonical analysis of the theory invariant under restricted diffeomorphism so that the action contains kinetic term for determinant of metric. We find corresponding Hamiltonian and determine structure of constraints.
High Energy Physics - Theory
[2306.16810] More On Pure Gravity with a Negative Cosmological Constant
https://arxiv.org/abs/2306.16810
We identify an ambiguity in the Chern-Simons formulation of three-dimensional gravity with negative cosmological constant that originates in an outer automorphism of the Lie algebra sl(2,R). It has important consequences for the stability of the theory in a space-time with boundary. We revisit the classical equivalence of three-dimensional gravity with a boundary Liouville theory both on and off the mass shell. Moreover, we provide further details on the quantum equivalence, the gauge symmetry that renders the spectrum diagonal, as well as the relation between asymptotically AdS3 metrics and polar boundary conditions. We thus set the proposal that the Liouville conformal field theory serves as a definition of a unitary theory of pure gravity in three dimensions with negative cosmological constant on a more stable footing.
[2306.13143] Bubbles of cosmology in AdS/CFT
https://arxiv.org/abs/2306.13143
[2306.15105] Holography and Correlation Functions of Huge Operators: Spacetime Bananas
https://arxiv.org/abs/2306.15105
Quantum Physics
[2306.14625] On the relation between quantum walks and absolute zeta functions
https://arxiv.org/abs/2306.14625
