5 papers
Revisiting Coincident GR in Internal STEGR Formulation
Kyosuke Tomonari, Taishi Katsuragawa, Shin'ichi Nojiri
We revisit Coincident General Relativity (CGR) in the gauge approach to gravity based on Symmetric Teleparallel Equivalent to General Relativity (STEGR) in the \textit{internal-spa…
Theoretical and observational constraints on early dark energy in gravity
Hua Chen, Taishi Katsuragawa, Shin'ichi Nojiri +1
This work examines an early dark energy (EDE) scenario in the context of gravity. EDE is introduced to alleviate the Hubble tension by temporarily injecting approximately $1…
Cosmological Perturbation in New General Relativity: Propagating mode from the violation of local Lorentz invariance
Kyosuke Tomonari, Taishi Katsuragawa, Shin'ichi Nojiri
We investigate the propagating modes of New General Relativity (NGR) in second-order linear perturbations in the Lagrangian density (first-order in field equations). The Dirac-Berg…
Compact star in noninteger power model of gravity
Yong-Xiang Cui, Zu Yan, Kota Numajiri +2
We investigate compact stars in the noninteger power (NIP) model of gravity theory, which includes the higher-curvature correction to the Einstein-Hilbert action. The mass-r…
Future singularity in an anisotropic universe
Taishi Katsuragawa, Shin'ichi Nojiri, Sergei D. Odintsov
We investigate future singularities originating from the anisotropy in the Universe. We formulate a new class of singularities in the homogeneous and anisotropic universe, comparin…