Fractional gravity yields stable de Sitter expansion and exact bouncing solutions driven by phantom (w < -1) or ghost (negative energy) fluids, with results independent of the form-factor representation.
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The Atacama Cosmology Telescope: DR6 Constraints on Extended Cosmological Models
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We use new cosmic microwave background (CMB) primary temperature and polarization anisotropy measurements from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) to test foundational assumptions of the standard cosmological model and set constraints on extensions to it. We derive constraints from the ACT DR6 power spectra alone, as well as in combination with legacy data from Planck. To break geometric degeneracies, we include ACT and Planck CMB lensing data and baryon acoustic oscillation data from DESI Year-1, and further add supernovae measurements from Pantheon+ for models that affect the late-time expansion history. We verify the near-scale-invariance (running of the spectral index $d n_s/d\ln k = 0.0062 \pm 0.0052$) and adiabaticity of the primordial perturbations. Neutrino properties are consistent with Standard Model predictions: we find no evidence for new light, relativistic species that are free-streaming ($N_{\rm eff} = 2.86 \pm 0.13$, which combined with external BBN data becomes $N_{\rm eff} = 2.89 \pm 0.11$), for non-zero neutrino masses ($\sum m_\nu < 0.082$ eV at 95% CL), or for neutrino self-interactions. We also find no evidence for self-interacting dark radiation ($N_{\rm idr} < 0.134$), early-universe variation of fundamental constants, early dark energy, primordial magnetic fields, or modified recombination. Our data are consistent with standard BBN, the FIRAS-inferred CMB temperature, a dark matter component that is collisionless and with only a small fraction allowed as axion-like particles, a cosmological constant, and the late-time growth rate predicted by general relativity. We find no statistically significant preference for a departure from the baseline $\Lambda$CDM model. In general, models introduced to increase the Hubble constant or to decrease the amplitude of density fluctuations inferred from the primary CMB are not favored by our data.
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representative citing papers
Galaxy pairwise peculiar velocities from Cosmicflows-4 yield M_ν = 0.24^{+0.34}_{-0.18} eV and η² = 2.14^{+0.30}_{-0.32} (7σ non-zero asymmetry) in the CMB framework, consistent with prior Planck results.
DESI DR1 Lyman-alpha data yields Δ²★=0.379±0.032 and n★=-2.309±0.019 at k★=0.009 km⁻¹s and z=3, sharpening N_eff, α_s, and β_s constraints by factors of 1.18-1.90 when combined with other probes.
An interacting sterile neutrino component via pseudoscalar mediator reconciles CMB and DESI DR2 BAO measurements with 2.7 sigma preference and reduces H0 tension to 2.4 sigma.
Gaussian process regression on nuclear data predicts 10^5 D/H = 2.442 ± 0.040, 1.70 sigma below observation and consistent with first-principles calculations.
A Gompertzian reionization model with three nuisance parameters demotes optical depth to a derived quantity, reducing its uncertainty by a factor of three and revealing potential neutrino mass tension in CMB analyses.
Bulk viscosity deforms the radiation era to produce a sign-definite Ricci scalar derivative, enabling gravitational baryogenesis to match the observed baryon asymmetry η_obs ≈ 8.6×10^{-11} for ξ in 10^{-4}–10^{-3}.
Nonminimal derivative coupling realizes the Harrison-Zeldovich attractor for monomial, hilltop, and α-attractor E-models, pulling them to the scale-invariant spectrum suggested by ACT data.
QML-FAST provides a fast, optimal QML power spectrum code for low-ℓ tomographic analysis of up to dozens of correlated scalar fields on the sphere, with public release and validation showing gains over pseudo-C_ℓ at large scales.
No evidence for primordial hotspots in Planck polarization data leads to improved bounds on inflationary particle production couplings for light particles.
Conventional BBN fitting for negative Delta N_eff is unphysical; a consistent treatment via entropy dilution after neutrino decoupling yields significantly different bounds.
SPT-3G delivers the most precise CMB EE and TE spectra at high multipoles to date, giving LCDM parameters with H0 = 66.66 ± 0.60 km/s/Mpc from ground-based data alone and reaching Planck-level constraints when combined with ACT.
Combining periodic non-minimal couplings to the Nieh-Yan term and Ricci scalar in metric-affine gravity makes natural inflation viable for sub-Planckian periodicity scales.
Inflaton accretion during reheating drives non-linear PBH mass growth that extends lifetimes and amplifies emitted SGWB by multiple orders of magnitude.
Positive running of the spectral index is achievable in Einstein-Gauss-Bonnet gravity with viable inflation, unlike standard scalar field and F(R) models which face challenges.
STVG-MOG makes pre-recombination scalar perturbations degenerate with ΛCDM by letting the vector field φ_μ act as collisionless pressureless dust with ρ_φ ∝ a^{-3} while keeping G_eff ≈ G_N on acoustic scales.
Naive nonlinear modelling of non-cold matter produces an artificial preference for a subdominant ultralight axion dark matter component at m ≈ 10^{-24} eV via a lensing-like enhancement in the CMB power spectrum.
Alpha-attractor quintessential inflation models are disfavored by DESI observations and Delta Neff limits from gravitational waves, as they predict an inconsistent scalar spectral index when the gravitational-wave abundance is constrained.
Including spectral running α_s, β_s and self-interacting dark radiation relaxes the ACT DR6 bound on ΔN_eff to <0.58 and lowers the Hubble tension to 2.2σ with three extra parameters.
Single-field inflation with ε(N) approaching a constant in (0,1) at early times forms an asymptotic universality class with a Weyl-flat null origin while producing ns and r values compatible with Planck data.
Genetic algorithm reconstructs single-field inflationary models with features in the scalar power spectrum that fit Planck 2018 CMB data better by Δχ² ≲ -10 and suggest alternative background parameters.
FolpsD combines EFT power spectrum and tree-level bispectrum with damping to enable joint analyses that improve cosmological constraints from DESI-like galaxy mocks by up to 30% on As and omega_cdm while extending the usable k-range without significant biases for LRG samples.
Early dark energy resolves CMB-BAO tension and, combined with thawing quintessence, reduces overall cosmological tensions without phantom crossing.
New ACT and DESI data yield model-dependent upper limits on sum of neutrino masses, with holographic dark energy giving the tightest bounds and a consistent preference for degenerate hierarchy.
citing papers explorer
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Cosmology of fractional gravity
Fractional gravity yields stable de Sitter expansion and exact bouncing solutions driven by phantom (w < -1) or ghost (negative energy) fluids, with results independent of the form-factor representation.
-
Measuring neutrino mass and asymmetry through galaxy pairwise peculiar velocity
Galaxy pairwise peculiar velocities from Cosmicflows-4 yield M_ν = 0.24^{+0.34}_{-0.18} eV and η² = 2.14^{+0.30}_{-0.32} (7σ non-zero asymmetry) in the CMB framework, consistent with prior Planck results.
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Cosmological analysis of the DESI DR1 Lyman alpha 1D power spectrum
DESI DR1 Lyman-alpha data yields Δ²★=0.379±0.032 and n★=-2.309±0.019 at k★=0.009 km⁻¹s and z=3, sharpening N_eff, α_s, and β_s constraints by factors of 1.18-1.90 when combined with other probes.
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Recoupled Dark Radiation reconciling CMB and DESI BAO measurements
An interacting sterile neutrino component via pseudoscalar mediator reconciles CMB and DESI DR2 BAO measurements with 2.7 sigma preference and reduces H0 tension to 2.4 sigma.
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A data-driven prediction for the primordial deuterium abundance
Gaussian process regression on nuclear data predicts 10^5 D/H = 2.442 ± 0.040, 1.70 sigma below observation and consistent with first-principles calculations.
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Into the Gompverse: A robust Gompertzian reionization model for CMB analyses
A Gompertzian reionization model with three nuisance parameters demotes optical depth to a derived quantity, reducing its uncertainty by a factor of three and revealing potential neutrino mass tension in CMB analyses.
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Sign-Locked Gravitational Baryogenesis from Bulk Viscosity and Cosmological Particle Creation
Bulk viscosity deforms the radiation era to produce a sign-definite Ricci scalar derivative, enabling gravitational baryogenesis to match the observed baryon asymmetry η_obs ≈ 8.6×10^{-11} for ξ in 10^{-4}–10^{-3}.
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Harrison-Zeldovich attractor: From Planck to ACT results
Nonminimal derivative coupling realizes the Harrison-Zeldovich attractor for monomial, hilltop, and α-attractor E-models, pulling them to the scale-invariant spectrum suggested by ACT data.
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QML-FAST -- A Fast Code for low-$\ell$ Tomographic Maximum Likelihood Power Spectrum Estimation
QML-FAST provides a fast, optimal QML power spectrum code for low-ℓ tomographic analysis of up to dozens of correlated scalar fields on the sphere, with public release and validation showing gains over pseudo-C_ℓ at large scales.
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Constraining Inflationary Particle Production with CMB Polarization
No evidence for primordial hotspots in Planck polarization data leads to improved bounds on inflationary particle production couplings for light particles.
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Consistent $N_{\rm eff}$ fitting in big bang nucleosynthesis analysis
Conventional BBN fitting for negative Delta N_eff is unphysical; a consistent treatment via entropy dilution after neutrino decoupling yields significantly different bounds.
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SPT-3G D1: CMB temperature and polarization power spectra and cosmology from 2019 and 2020 observations of the SPT-3G Main field
SPT-3G delivers the most precise CMB EE and TE spectra at high multipoles to date, giving LCDM parameters with H0 = 66.66 ± 0.60 km/s/Mpc from ground-based data alone and reaching Planck-level constraints when combined with ACT.
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Natural Metric-Affine Inflation: Reloaded
Combining periodic non-minimal couplings to the Nieh-Yan term and Ricci scalar in metric-affine gravity makes natural inflation viable for sub-Planckian periodicity scales.
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Inflaton Accretion onto Primordial Black Holes During Reheating
Inflaton accretion during reheating drives non-linear PBH mass growth that extends lifetimes and amplifies emitted SGWB by multiple orders of magnitude.
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Positive Running of the Spectral Index for Scalar Theory and Modified Gravity
Positive running of the spectral index is achievable in Einstein-Gauss-Bonnet gravity with viable inflation, unlike standard scalar field and F(R) models which face challenges.
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CMB Acoustic Power Spectra in STVG-MOG
STVG-MOG makes pre-recombination scalar perturbations degenerate with ΛCDM by letting the vector field φ_μ act as collisionless pressureless dust with ρ_φ ∝ a^{-3} while keeping G_eff ≈ G_N on acoustic scales.
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Ultra-light axion constraints from Planck and ACT: the role of nonlinear modelling
Naive nonlinear modelling of non-cold matter produces an artificial preference for a subdominant ultralight axion dark matter component at m ≈ 10^{-24} eV via a lensing-like enhancement in the CMB power spectrum.
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DESI and Gravitational Wave Constraints Challenge Quintessential {\alpha}-Attractor Inflation
Alpha-attractor quintessential inflation models are disfavored by DESI observations and Delta Neff limits from gravitational waves, as they predict an inconsistent scalar spectral index when the gravitational-wave abundance is constrained.
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The End of the First Act: Spectral Running, Interacting Dark Radiation, and the Hubble Tension in Light of ACT DR6 Data
Including spectral running α_s, β_s and self-interacting dark radiation relaxes the ACT DR6 bound on ΔN_eff to <0.58 and lowers the Hubble tension to 2.2σ with three extra parameters.
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Inflation from a Weyl-flat null origin
Single-field inflation with ε(N) approaching a constant in (0,1) at early times forms an asymptotic universality class with a Weyl-flat null origin while producing ns and r values compatible with Planck data.
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Reconstructing inflationary features on large scales using genetic algorithm
Genetic algorithm reconstructs single-field inflationary models with features in the scalar power spectrum that fit Planck 2018 CMB data better by Δχ² ≲ -10 and suggest alternative background parameters.
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FolpsD: combining EFT and phenomenological approaches for joint power spectrum and bispectrum analyses
FolpsD combines EFT power spectrum and tree-level bispectrum with damping to enable joint analyses that improve cosmological constraints from DESI-like galaxy mocks by up to 30% on As and omega_cdm while extending the usable k-range without significant biases for LRG samples.
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Disentangling cosmic distance tensions with early and late dark energy
Early dark energy resolves CMB-BAO tension and, combined with thawing quintessence, reduces overall cosmological tensions without phantom crossing.
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Measuring neutrino mass in light of ACT DR6 and DESI DR2
New ACT and DESI data yield model-dependent upper limits on sum of neutrino masses, with holographic dark energy giving the tightest bounds and a consistent preference for degenerate hierarchy.
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Self-resonance preheating in deformed attractor models: oscillon formation and evolution
Deformed alpha-attractor T-models with a Gaussian feature near the minimum yield more smaller shorter-lived oscillons during self-resonance preheating, suppressing energy in oscillons and altering the high-frequency gravitational wave tail while leaving low frequencies unchanged.
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Temperature-Dependent CPT Violation: Constraints from Big Bang Nucleosynthesis
Constraints on temperature-dependent CPT-violating electron-positron mass asymmetry b0(T) = α T² from BBN abundances of 4He, D, and Neff give α ≳ 10^{-6} GeV^{-1} for keV-scale effects at BBN.
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Curvaton-assisted hilltop inflation
Curvaton coupling relaxes initial tuning in hilltop inflation and revives the sub-Planckian quartic model while remaining consistent with cosmological observations.
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Cosmological Probes of Lepton Parity Freeze-in Dark Matter: $\Delta N_{\rm eff}$ & Gravitational Waves
Lepton parity stabilizes a Majorana fermion as freeze-in dark matter produced via right-handed neutrino or Higgs decays, yielding detectable gravitational waves or ΔN_eff depending on scalar couplings.
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Inflation in theories with broken diffeomorphisms
Breaking diffeomorphism invariance to transverse diffeomorphisms in the inflaton sector yields modified slow-roll parameters and power spectra with novel post-inflationary regimes for quadratic potentials.
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The implications of inflation for the last ACT
A parameterized slow-roll model and a new exponential f(R) inflation model are constrained by P-ACT-LB-BK18 data, with the latter aligning to the ACT scalar spectral index preference in both standard and EDE frameworks.
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SPT-3G D1: Axion Early Dark Energy with CMB experiments and DESI
CMB-only data give f_EDE < 0.07 at 95% CL with no strong AEDE signal, while CMB+DESI yields f_EDE = 0.055^{+0.024}_{-0.047} at 68% CL and lowers Hubble tension to 2.6 sigma.
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Type II Seesaw Leptogenesis in a Majoron background
Spontaneous wash-in leptogenesis in Type II Seesaw with Majoron pNGB background enables baryon asymmetry generation alongside dark matter cogenesis for specific v_T, v_sigma and m_j ranges.
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ACT-ing on inflation: Implications of non Bunch-Davies initial condition and reheating on single-field slow roll models
Non-Bunch-Davies initial conditions substantially improve the fit of various single-field slow-roll inflation models to updated n_s-r constraints from ACT DR6 combined with Planck, DESI, and BICEP/Keck data.
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DEMNUni: the Sunyaev-Zel'dovich effect in the presence of massive neutrinos and dynamical dark energy
N-body simulations show the log Compton-y distribution mean decreases linearly with neutrino fraction (slope ~10 f_ν) and tSZ power spectrum scales as power law in σ8^cb (exponents 7.3-8.1), with ∑m_ν=0.16 or 0.32 eV fitting Planck data better than massless case.
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Warm inflation in Weyl geometric gravity
Warm inflation with linear dissipation and quartic potential is realized in Weyl geometric gravity, incorporating the Weyl vector to produce a smooth transition to radiation domination with observables consistent with ACT data.
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F-Term Hybrid Inflation with T-Model K\"ahler Geometry and Beyond
F-term hybrid inflation with SU(1,1)/U(1) or SU(2)/U(1) Kähler geometry in GUTs can be realized without inflationary extrema for broad parameters, matching ACT/SPT data via curvature and tadpole adjustments while predicting cosmic string gravitational waves.
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The Status of Gravitational Vector Perturbations with Recent CMB Data
Recent CMB datasets tighten 95% CL upper bounds on vector-mode amplitude r_v to 1.3e-4 (neutrino isocurvature), 6.8 (octupole), and 4.2 (sourced) at k=0.05 Mpc^-1, with no significant detection.
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Constraining Tsallis Corrections to Photon Reheating from Electron-Positron Annihilation
Generalizing entropy from e+e- annihilation with Tsallis statistics for pairs only leads to a 2σ bound of |q-1| ≤ 1.3×10^{-2} from CMB+BAO+BBN data.
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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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Constraining Quintessential Inflation with ACT: A Gauss-Bonnet Gateway
Einstein-Gauss-Bonnet corrections with exponential or sech couplings shift quintessential inflation into the 1 sigma ACT region for r and ns, while tanh coupling remains disfavored.
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Loop Blow-up Inflation: An Overview
String loop corrections in blow-up inflation generate a power-law plateau at large fields, raising the tensor-to-scalar ratio while keeping all three Standard Model location scenarios consistent with latest observations after updating one coefficient for dark radiation bounds.
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Induced-Gravity Palatini-Like Higgs Inflation in Supergravity Confronts ACT DR6
A Palatini-inspired induced-gravity inflation model in supergravity fits ACT DR6 data while embedding into a B-L extended MSSM with split SUSY and leptogenesis.
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Reheating in geometric Weyl-invariant Einstein-Cartan gravity
Reheating temperature and equation-of-state parameter assumptions in Weyl-invariant Einstein-Cartan gravity models significantly alter predicted inflationary observables.
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KiDS-Legacy: Constraining dark energy, neutrino mass, and curvature
KiDS-Legacy cosmic shear plus external probes yields S8 = 0.816 ± 0.006 in Lambda-CDM and consistent bounds on w0, wa, sum m_nu and Omega_K with no strong preference for extensions.
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ACT-Era Constraints on Single-Field Inflation in $f(T)$ Teleparallel Gravity
Modest positive δ in f(T) teleparallel gravity suppresses r while keeping ns near its slow-roll value, restoring viability for sub-quadratic monomials and hilltop models disfavored in GR under ACT constraints.
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Assisted Fibre Inflation in Perturbative LVS
Multi-field fibre inflation in perturbative LVS uses collective dynamics of several moduli to achieve viable cosmology with sub-Planckian individual field ranges given by total range divided by sqrt(n).
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Dark Energy in Ghost-free non-local Gravity
Ghost-free non-local gravity fits Pantheon+, DESI, and H(z) data but fails with added CMB, while generalized exponential F(R) gravity outperforms Lambda CDM across all datasets including CMB.
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Constraints on non-canonical chaotic inflation from ACT DR6 and BICEP/Keck data
MCMC fitting of joint P-ACT-LB-BK18 dataset constrains non-canonical parameter alpha to 8.8, 11.7, and 16.4 (1 sigma) for chaotic inflation potentials with n=1/3, 2/3, 1 respectively.
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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.