Gravitational memory from hairy binary black hole mergers in scalar-Gauss-Bonnet gravity differs from GR by a few percent due to altered nonlinear dynamics, with direct scalar contributions suppressed, and including memory increases GR-sGB mismatch by more than an order of magnitude.
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Modified Gravity Theories on a Nutshell: Inflation, Bounce and Late-time Evolution
Canonical reference. 90% of citing Pith papers cite this work as background.
abstract
We systematically review some standard issues and also the latest developments of modified gravity in cosmology, emphasizing on inflation, bouncing cosmology and late-time acceleration era. Particularly, we present the formalism of standard modified gravity theory representatives, like $F(R)$, $F(\mathcal{G})$ and $F(T)$ gravity theories, but also several alternative theoretical proposals which appeared in the literature during the last decade. We emphasize on the formalism developed for these theories and we explain how these theories can be considered as viable descriptions for our Universe. Using these theories, we present how a viable inflationary era can be produced in the context of these theories, with the viability being justified if compatibility with the latest observational data is achieved. Also we demonstrate how bouncing cosmologies can actually be described by these theories. Moreover, we systematically discuss several qualitative features of the dark energy era by using the modified gravity formalism, and also we critically discuss how a unified description of inflation with dark energy era can be described by solely using the modified gravity framework. Finally, we also discuss some astrophysical solutions in the context of modified gravity, and several qualitative features of these solutions. The aim of this review is to gather the different modified gravity techniques and form a virtual modified gravity "toolbox", which will contain all the necessary information on inflation, dark energy and bouncing cosmologies in the context of the various forms of modified gravity.
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background 20representative citing papers
Dissipation of small-scale primordial perturbations after neutrino decoupling cools relic neutrinos and reduces their abundance, enabling PTOLEMY to constrain the primordial curvature power spectrum to O(0.1) on scales k ≲ 3×10^5 Mpc^{-1}.
Non-polynomial quasi-topological gravity models reproduce the standard thermal history, generate dynamical dark energy of geometric origin, and fit supernova, cosmic chronometer, and BAO data competitively with ΛCDM.
Galileon models must obey a void-depth limit tied to expansion history to avoid force breakdowns, excluding ~60% of a linear parameterization's space by z less than or equal to 10.
Higher-curvature gravities are constructed in which both FLRW backgrounds and linearized scalar perturbations obey at most second-order differential equations.
Semi-analytical calculation of void-galaxy cross-correlation multipoles in Hu-Sawicki f(R) gravity reveals size-dependent deviations from LambdaCDM up to 29.7 percent for small voids, amplified by nonlinear evolution and potentially observable in Stage-IV surveys.
Binary black hole mergers in Ricci-coupled scalar-Gauss-Bonnet gravity produce an observable scalar breathing memory signal from the merger-driven change in scalar charge, potentially matching the size of the theory's tensor-memory correction.
A phase-space gating function μ(φ,X) localizes Gauss-Bonnet contributions to a finite e-fold window in inflation while preserving ghost and gradient stability for scalar and tensor modes.
Scalar and tensor perturbations in Jordan-frame scalar-tensor gravity admit an exact linear-order Eckart effective-fluid description, with gravitational-wave damping governed by the scalar sector's transverse-traceless anisotropic stress.
In f(R,T) = R + F(T) gravity, nonlinear F makes the averaged modified term differ from F at averaged T, invalidating the common unity-ratio assumption and giving dust nonzero proper pressure.
Sign-switching dark energy with a transition at z_† fits recent DESI DR2, Planck CMB, and Pantheon+ data better than ΛCDM while raising the inferred Hubble constant and easing the Hubble tension.
Boson stars in teleparallel gravity with nonminimal coupling show negative energy density and energy-condition violation in excited states, with EMRI waveforms potentially detectable by LISA.
In symmetric teleparallel f(Q) gravity with nonminimal EM-nonmetricity coupling, the distance duality relation is dynamically violated, yielding a generalized formula relating observational distances to the Hubble rate.
Introduces Fractional Holographic Dark Energy (FHDE) via fractionally corrected entropy from a modified Wheeler-DeWitt equation and studies its late-time cosmology, field reconstructions, and extensions to modified gravity theories.
An effective constrained scalar-Gauss-Bonnet inflation model yields n_s ≃ 0.958 and r ≃ 2.7×10^{-4} while the exact theory has no propagating scalar degree of freedom.
Generalized hybrid metric-Palatini gravity propagates a massless spin-2 mode and two massive scalars in the weak field; stability requires algebraic conditions on f derivatives at flat space, and planetary data constrain the scalar masses in a hierarchical regime.
Using FLRW cosmology to connect generalized uncertainty principle modifications to modified gravity shows that only Born-Infeld models remain natural in both settings.
A non-canonical generalized Brans-Dicke theory admits background cosmological solutions matching Lambda CDM characteristics for constant, power-law, and exponential potentials, with dynamics distinct from other scalar-tensor models.
Rényi entropic corrections to cosmology are constrained by DESI DR2 BAO and GW data to a viable quintessence-like model that approaches ΛCDM without phantom behavior and satisfies BBN bounds.
Generalized horizon entropy models satisfy BBN constraints on helium and deuterium abundances when parameters are chosen for cosmic acceleration, though lithium remains discrepant as in standard cosmology.
Nonlocal black holes remain consistent with general relativity at the 1.13-sigma level after joint lensing and quasinormal-mode constraints.
f(Q) gravity yields Taub-de Sitter-like plane symmetric vacuum solutions, and quadratic models support isotropic slabs where maximum pressure is offset from the center with thickness and pressure increasing for negative α.
A systematic mapping is derived from GUP parameters in minimal-length quantum theory to higher-order curvature coefficients in extended gravity, with an application yielding an upper bound on the minimal measurable length via light deflection corrections.
Fuzzy dark matter induces frequency-dependent amplitude birefringence in gravitational waves with periodic time modulation set by the scalar mass, but no velocity birefringence.
citing papers explorer
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Gravitational Memory from Hairy Binary Black Hole Mergers
Gravitational memory from hairy binary black hole mergers in scalar-Gauss-Bonnet gravity differs from GR by a few percent due to altered nonlinear dynamics, with direct scalar contributions suppressed, and including memory increases GR-sGB mismatch by more than an order of magnitude.
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Probing the small-scale primordial power spectrum via relic neutrinos and acoustic reheating
Dissipation of small-scale primordial perturbations after neutrino decoupling cools relic neutrinos and reduces their abundance, enabling PTOLEMY to constrain the primordial curvature power spectrum to O(0.1) on scales k ≲ 3×10^5 Mpc^{-1}.
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Cosmologically viable non-polynomial quasi-topological gravity: explicit models, $\Lambda$CDM limit and observational constraints
Non-polynomial quasi-topological gravity models reproduce the standard thermal history, generate dynamical dark energy of geometric origin, and fit supernova, cosmic chronometer, and BAO data competitively with ΛCDM.
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How deep can a cosmic void be? Voids-informed theoretical bounds in Galileon gravity
Galileon models must obey a void-depth limit tied to expansion history to avoid force breakdowns, excluding ~60% of a linear parameterization's space by z less than or equal to 10.
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Cosmological higher-curvature gravities
Higher-curvature gravities are constructed in which both FLRW backgrounds and linearized scalar perturbations obey at most second-order differential equations.
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Unveiling $f(R)$ Gravity with Void-Galaxy Cross-Correlation Multipoles
Semi-analytical calculation of void-galaxy cross-correlation multipoles in Hu-Sawicki f(R) gravity reveals size-dependent deviations from LambdaCDM up to 29.7 percent for small voids, amplified by nonlinear evolution and potentially observable in Stage-IV surveys.
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Scalar memory from compact binary coalescences
Binary black hole mergers in Ricci-coupled scalar-Gauss-Bonnet gravity produce an observable scalar breathing memory signal from the merger-driven change in scalar charge, potentially matching the size of the theory's tensor-memory correction.
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Beyond $f(\phi)\mathcal{G}$: Gauss--Bonnet inflation with $\mu(\phi,X)$
A phase-space gating function μ(φ,X) localizes Gauss-Bonnet contributions to a finite e-fold window in inflation while preserving ghost and gradient stability for scalar and tensor modes.
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Thermal channels of scalar and tensor waves in Jordan-frame scalar--tensor gravity
Scalar and tensor perturbations in Jordan-frame scalar-tensor gravity admit an exact linear-order Eckart effective-fluid description, with gravitational-wave damping governed by the scalar sector's transverse-traceless anisotropic stress.
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Cosmological Averaging in Nonminimally Coupled Gravity
In f(R,T) = R + F(T) gravity, nonlinear F makes the averaged modified term differ from F at averaged T, invalidating the common unity-ratio assumption and giving dust nonzero proper pressure.
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Sign-Switching Dark Energy: Smooth Transitions with Recent DESI DR2 Observations
Sign-switching dark energy with a transition at z_† fits recent DESI DR2, Planck CMB, and Pantheon+ data better than ΛCDM while raising the inferred Hubble constant and easing the Hubble tension.
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Boson Stars in Teleparallel Gravity with a Nonminimally Coupled Field: The Violation of Energy Conditions and Gravitational Waveforms from EMRIs
Boson stars in teleparallel gravity with nonminimal coupling show negative energy density and energy-condition violation in excited states, with EMRI waveforms potentially detectable by LISA.
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Distance duality relation in symmetric teleparallel gravity
In symmetric teleparallel f(Q) gravity with nonminimal EM-nonmetricity coupling, the distance duality relation is dynamically violated, yielding a generalized formula relating observational distances to the Hubble rate.
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An Interplay Between Fractional Calculus and Holographic Dark Energy
Introduces Fractional Holographic Dark Energy (FHDE) via fractionally corrected entropy from a modified Wheeler-DeWitt equation and studies its late-time cosmology, field reconstructions, and extensions to modified gravity theories.
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Effective Constrained Scalar--Gauss--Bonnet Inflation Motivated by $f(R,\mathcal{G})$ Gravity
An effective constrained scalar-Gauss-Bonnet inflation model yields n_s ≃ 0.958 and r ≃ 2.7×10^{-4} while the exact theory has no propagating scalar degree of freedom.
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Another Look at the Weak-Field Limit of Generalized Hybrid Metric-Palatini Gravity
Generalized hybrid metric-Palatini gravity propagates a massless spin-2 mode and two massive scalars in the weak field; stability requires algebraic conditions on f derivatives at flat space, and planetary data constrain the scalar masses in a hierarchical regime.
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Natural modification of quantum uncertainty, modified gravity, and cosmology
Using FLRW cosmology to connect generalized uncertainty principle modifications to modified gravity shows that only Born-Infeld models remain natural in both settings.
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Cosmological Dynamics of a Non-Canonical Generalised Brans-Dicke Theory
A non-canonical generalized Brans-Dicke theory admits background cosmological solutions matching Lambda CDM characteristics for constant, power-law, and exponential potentials, with dynamics distinct from other scalar-tensor models.
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Exploring Cosmic Evolution in R\'enyi Entropic Cosmology with Constraints from DESI DR2 BAO and GW Data
Rényi entropic corrections to cosmology are constrained by DESI DR2 BAO and GW data to a viable quintessence-like model that approaches ΛCDM without phantom behavior and satisfies BBN bounds.
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Viability of Big Bang Nucleosynthesis in Some Generalized Horizon Entropies
Generalized horizon entropy models satisfy BBN constraints on helium and deuterium abundances when parameters are chosen for cosmic acceleration, though lithium remains discrepant as in standard cosmology.
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Observational constraints on nonlocal black holes via gravitational lensing
Nonlocal black holes remain consistent with general relativity at the 1.13-sigma level after joint lensing and quasinormal-mode constraints.
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Static plane symmetric solutions in $f(Q)$ gravity
f(Q) gravity yields Taub-de Sitter-like plane symmetric vacuum solutions, and quadratic models support isotropic slabs where maximum pressure is offset from the center with thickness and pressure increasing for negative α.
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From minimal-length quantum theory to modified gravity
A systematic mapping is derived from GUP parameters in minimal-length quantum theory to higher-order curvature coefficients in extended gravity, with an application yielding an upper bound on the minimal measurable length via light deflection corrections.
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Gravitational Wave Birefringence from Fuzzy Dark Matter
Fuzzy dark matter induces frequency-dependent amplitude birefringence in gravitational waves with periodic time modulation set by the scalar mass, but no velocity birefringence.
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Classical and Loop Quantum Cosmology of Interacting Dark Energy: A Dynamical System Analysis with Superfluid Dark Matter and Dust Matter
Dynamical systems analysis shows loop quantum cosmology removes stable attractors in interacting dark energy-dark matter models that exist under classical gravity.
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Three-form dark energy: constraints and multi-probe comparison with $\Lambda$CDM
A Gaussian three-form dark-energy model is viable and mildly preferred over ΛCDM only for the tensioned CMB+BAO+Pantheon+SH0ES combination, with a phantom dip at intermediate redshifts.
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Resolving the Hubble Tension in the Early Dark Energy Framework with JWST and DESI Data
Axion EDE model fitted to Planck/ACT/SPT CMB, DESI BAO, and JWST UV luminosity function data yields H0 = 71.58 ± 1.05 km s^{-1} Mpc^{-1}, reduces H0 tension to 1.0 sigma, and improves Δχ^{2}_tot = -18.26 over Λ CDM.
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Mass Varying Neutrino Oscillation in Teleparallel Gravity
Torsion-coupled scalar in teleparallel gravity induces density-dependent neutrino masses that alter MSW resonance and yield constraints on coupling parameters from Super-Kamiokande, Borexino and SNO data.
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Integrability of $R^2$ gravity cosmological models with radiation
Derives general solution to □R=0 in R² gravity plus radiation in flat FLRW and establishes integrability of the scalar-field and conformal chiral versions.
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Lagrangian Extensions of Newtonian Gravity constrained by Solar System tests
Derives post-Newtonian equations from a scalar-extended Newtonian Lagrangian and bounds its free parameter with Solar System observations.
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Quark Stars in Ricci-Determinant Gravity with an Interacting Quark Equation of State
Quark stars in Ricci-Determinant gravity with interacting quark EoS exhibit lower compactness than in GR and become unstable at high central densities when perturbative gravity terms exceed about half the GR contribution.
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Reconstructing ACT-compatible and GW170817-compatible Einstein-Gauss-Bonnet Inflation from the Observational Indices
Four Einstein-Gauss-Bonnet inflationary models are reconstructed from a chosen tensor-to-scalar ratio and shown to satisfy ACT and GW170817 constraints including scalar perturbation amplitude.
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Constraints on Kaniadakis Cosmology from Starobinsky Inflation and Primordial Tensor Perturbations
Kaniadakis entropic cosmology modifies early-universe dynamics and is constrained by its predictions for Starobinsky inflation and the primordial tensor spectrum using current CMB and gravitational-wave observations.
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Unified Cosmological Scenario in Holographic $f(Q)$ gravity: From Inflation to Late-Time Acceleration
A holographic f(Q) = ζ Q^n model yields slow-roll inflation consistent with Planck 2018 and late-time expansion compatible with CC+BAO data via CPL parametrization, with mild high-z deviations from ΛCDM.
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ACT Data and Positive Running of the Spectral Index for Scalar Theory and Modified Gravity
Einstein-Gauss-Bonnet inflation can yield positive spectral-index running with a viable era under ACT-like hints, while scalar-field and F(R) models largely cannot.
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Singularity softening and avoidance by the action of thermal radiation in a generalized entropic cosmology
Hawking radiation induces a qualitative softening or complete avoidance of the Big Rip singularity in this viscous dark-fluid entropic cosmology.
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String-inspired Gauss-Bonnet Gravity Inflation and ACT
MCMC analysis of sixteen ghost-free f(R,G) inflation models shows all reproduce ns ≈ 0.97 at 60 e-folds with stable μ ≈ 0.1, preference set by Hubble parametrization.
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Energy conditions of bouncing solutions in quadratic curvature gravity coupled with a scalar field
Bouncing solutions in quadratic curvature gravity with a scalar field satisfy null, weak, and dominant energy conditions but violate the strong one when using the scalar-field energy-momentum tensor, while all four conditions are violated near the bounce in the effective tensor formulation.
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Probing departures from $\Lambda$CDM by late-time datasets
Late-time datasets yield 1-2.74σ preference for dynamical dark energy over ΛCDM, with consistent signs of Quintom-B behavior (ω0 > -1, ωa < 0) that strengthen when DES-Dovekie or Union3 supernovae are added.
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On Scalar Cosmological Perturbations in Non-Minimally Coupled Weyl Connection Gravity
Derives cosmological field equations and preliminary scalar perturbation equations for a non-minimally coupled Weyl-connection gravity model that introduces non-metricity to mimic dark sectors.
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Theoretical and observational constraints on early dark energy in $F(R)$ gravity
The work derives background-level constraints showing that potential-driven early dark energy in F(R) gravity is generically excluded by local gravity tests.
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Cosmological structure growth in energy-momentum squared gravity
In f(R,T²) gravity, the growth index decreases with redshift and approaches standard matter-dominated values at early times, with fσ8 predictions staying within ±2σ observational bounds for viable coupling parameters α and n=1/2 or 1/4.
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Probing cosmic dynamics in $f(T)$ teleparallel gravity: Constraints from logarithmic and log-periodic deceleration ansatzes
The authors constrain power-law f(T) teleparallel gravity models via logarithmic and log-periodic deceleration parameter ansatzes fitted to cosmic chronometer and Pantheon datasets, finding departure from ΛCDM.
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Effect of $R^2$ on the stability of de Sitter solution of the generalized Einsteinian cubic gravity
Generalized Einsteinian cubic gravity admits a de Sitter solution from the P cubic term alone; stability analysis is incomplete until the R^2 term is added, which leaves the solution value unchanged.
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Causality Violating Solutions in Curvature-Squared Gravity
Godel and Godel-type metrics satisfy the curvature-squared field equations as causal solutions with all Weyl tensor contributions removed, while an axially symmetric metric shows Weyl-dependent modifications to energy density and the weak energy condition.
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Scalar-Field Reconstruction of Ricci--Gauss--Bonnet Dark Energy in Ho\v{r}ava--Lifshitz Cosmology
Scalar-field reconstruction of Ricci-Gauss-Bonnet dark energy in Hořava-Lifshitz cosmology produces an equation of state that transitions smoothly to de Sitter-like behavior at late times, with stable sound speed and non-negative total entropy change at the apparent horizon.
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Transiently accelerating cosmological model with Gong-Zhang parametrization in $f(T)$ teleparallel gravity
In f(T) gravity with Gong-Zhang EoS parametrization, the fitted model shows transient acceleration followed by future deceleration and satisfies thermodynamic consistency.
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Inflationary models in a minimally coupled $f(R,T)$ gravity: Constraints from $Planck$, BICEP/$Keck$, and ACT
Three standard inflationary potentials remain compatible with Planck, BICEP/Keck, DESI DR2, and ACT DR6 data when placed in minimally coupled f(R,T)=R+16πGλT gravity for suitable ranges of the model parameters and coupling λ.
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Reconstructing the cosmic expansion in $f(R, L_{m})$ gravity via parametrized Hubble function constraints
Three H(z) parametrizations in f(R, L_m) = R/2 + L_m^λ gravity are constrained via chi-squared minimization on CC and CC+Pantheon data, with derived quantities for deceleration, EoS, energy conditions, statefinders, and thermodynamics shown to be consistent with observations.
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The $f(Q, T)$ gravity and affine EoS: observational aspects
f(Q,T) gravity with linear form and affine EoS is constrained by CC, Pantheon+SH0ES and DESI BAO data, yielding a present universe age consistent with Planck within 1σ.