Power-law f(R) model with single parameter δ yields stable growth enhancements matching fσ8 observations
Single-parameter power-law f(R) gravity passes viability tests and predicts enhanced linear growth testable by upcoming surveys. Evidence rests on analytic stability conditions plus numerical integration of perturbations; no data likelihoods are reported. Forthcoming LSS measurements can falsify the δ window within three years.
The study solves the modified Friedmann and perturbation equations analytically and numerically for a flat FLRW background, introducing an effective G_eff(z) that rises above Newton’s constant at late times. Growth factor D(a), growth rate f(z), and growth index γ are computed for several δ values and compared against ΛCDM. The single-parameter model reproduces the observed late-time acceleration and passes ghost-free, positive-mass, and de-Sitter stability tests without extra fields. fσ8(z) predictions lie within current error bars yet diverge measurably from ΛCDM at z<0.5. Because the work remains purely theoretical, it lacks direct confrontation with DESI or Euclid covariance matrices. A full MCMC analysis against combined CMB, BAO, and weak-lensing datasets would tighten δ bounds and test whether the reported growth excess survives parameter marginalization.
Verma et al.: Euclid DR1 fσ8 measurements at z=0.3 will exclude δ>0.15 at >3σ if the reported growth excess is physical.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2606.19402)
- [2]Supporting Source(https://arxiv.org/abs/2305.06338)