Описание
Gravitation & Cosmology: gravity, dark matter
I review several aspects of nonlocal field theory and nonlocal quantum gravity
These fields scale as, $\tilde\phi (\psi)=\Omega^\xi\,\phi(\psi)$ and the metric tensor as $\tilde{g}_{\mu\nu}=\Omega^2\,g_{\mu\nu}$, where $\Omega$ and $\xi$ are called the conformal factor and wight, respectively. The conformal mass in Klein-Gordon mass ($\tilde m$) is related to original scalar mass, ($m$) by $\tilde{m}=\Omega^{-1}\,m$\,. Moreover, the Klein-Gordon equation in the...
We summarize results on spherically symmetric loop quantum gravity, including singularity elimination, Hawking radiation and the Casimir effect.
Information on the subject:
- R Gambini, J. Olmedo, JP, CQG 31 095009 (2014) arXiv:1310.5996
- Bambi, Modesto, Shapiro ”Handbook of Quantum Gravity” (2023)
[gr-qc] 2211.05621 - R. Gambini, JP, Class.Quant.Grav. 31 (2014) 115003; 1312.3595...
It is shown that the dense population of the early universe with well developed galaxies and supermassive black holes (quasars), observed by HST and JWST, nicely fits the conjecture that the galaxies and quasars are seeded by primordial black holes (PBHs), proposed in our work more than 30 years ago. This idea of galaxy seeding by massive black holes is rediscovered in recent publications by...
Second-order-derivative plus fourth-order-derivative gravity is the ultraviolet completion of second-order-derivative quantum Einstein gravity. While it achieves renormalizability through states of negative Dirac norm, the unitarity violation that this would entail can be postponed to Planck energies. As we show in this paper the theory has a different problem, one that occurs at all energy...
We present and discuss well known conditions for ultraviolet finiteness and asymptotic safety. The requirements for complete absence of ultraviolet divergences in quantum field theories and existence of a non-trivial fixed point for renormalization group flow in the ultraviolet regime are compared based on the example of a six-derivative quantum gravitational theory in d=4 spacetime...
