Some late-time cosmological aspects of a Gauss–Bonnet gravity with nonminimal coupling à la Brans–Dicke: solutions and perspectives
Bibliographic record
Abstract
In this paper, we study modified homogeneous and isotropic cosmological models based on the Gauss–Bonnet invariant term as models of an accelerating universe. We discuss and criticize the late-time dynamics of six independent cosmological models: in the first model, we discuss the case of the modified gravity f(R) ∝ R 1+δ for δ = −1/2 and 1 augmented by the Gauss–Bonnet invariant term; in the second model, we discuss the general case of f(R) ∝ R 1+δ accompanied by a nonminimal coupling between the scalar field and the Ricci curvature as well as the Gauss–Bonnet invariant; in the third model, we discuss a generalized modified gravity model that includes the Einstein–Hilbert action, a dynamical cosmological constant, and an effective gravitational coupling constant; in the fourth model, we discuss a more generalized modified scalar–tensor cosmology that includes in addition to the Gauss–Bonnet invariant term, stringy corrections motivated from string and heterotic superstring arguments; in the fifth model, we discuss the cosmological dynamics of a nonminimal scalar Gauss–Bonnet gravity theory motivated from string theory; and finally in the sixth model, we discuss the possibility of having an extension of the generalized modified gravity theory, free from nonminimal coupling with δ = 0, with a Hubble expansion rate and an equation of state parameter that depend on the Gauss–Bonnet invariant term. In the first five models, we conjecture that the Hubble parameter is related to the scalar field by the relation [Formula: see text], which is applied merely to the late time epoch. This ansatz is in fact motivated by some recent advances in scalar–tensor theory and string theory. All of the six models reveal interesting consequences, which are discussed in some detail. Our main objective in this work is to analyze, criticize, and differentiate between viable realistic models and those that are not. Many critical points are discussed in some detail.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".