Very Hairy Inflation

Abstract

We revisit the rollercoaster cosmology based on multiple stages of monodromy inflation. Working within the framework of effective flux monodromy field theory, we include the full range of strong coupling corrections to the inflaton sector. We find that flattened potentials V ∼ φ p + . . . with p < ∼ 1/2, limited to N < ∼ 25 − 40 efolds in the first stage of inflation, continue to fit the CMB. They yield 0.96 < ∼ n s < ∼ 0.97, and produce relic gravity waves with 0.006 < ∼ r < ∼ 0.035, in full agreement with the most recent bounds from BICEP/Keck. The nonlinear derivative corrections generated by strong dynamics in EFT also lead to equilateral non-Gaussianity f eq N L O(1) − O(10), close to the current observational bounds. Finally, in multi-stage rollercoaster, an inflaton-hidden sector U (1) coupling can produce a tachyonic chiral vector background, which converts rapidly into tensors during the short interruption by matter domination. The produced stochastic gravity waves are chiral, and so they may be clearly identifiable by gravity wave instruments like LISA, Big Bang Observatory, Einstein Telescope, NANOgrav or SKA, depending on the precise model realization. We also point out that the current attempts to resolve the H 0 tension using early dark energy generically raise n s . This may significantly alter the impact of BICEP/Keck data on models of inflation.

Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies

“…We would like to point out, as done in [677], an interesting consequence of several models aimed at addressing the Hubble tension, in particular early dark energy models and NEDE (but also models with extra relativistic degrees of freeedom). Fitting CMB data in terms of these models, a common feature is that the spectral index is bluer with respect to the ΛCDM value (see [575,[678][679][680][681]): such a shift of n s will have very important implications for inflationary model constraints.…”

Anisotropic cosmic optical background bound for decaying dark matter in light of the LORRI anomaly

“…7 Given the 5 σ Hubble tension, the bound on the hot DM may be different, c.f. the inflationary scenarios for explaining unusual primordial density perturbation required from various models for the Hubble tension [71,72] (See also [73,74] for the discussion to obtain n s ∼ 1 in order to alleviate the Hubble tension. )…”

Power-law Inflation Satisfies Penrose's Weyl Curvature Hypothesis

“…However, since the exponential potential by itself can't be the whole story, after all needing corrections to accommodate reheating at the very least [38], those deviations could fit [44]. Alternatively, if the resolution of the H 0 tension forces a modification of ΛCDM, by for example inclusion of the EDE [45][46][47], the primordial scalar spectrum may need to be slightly modified to compensate for the change in the evolution of fluctuations [48][49][50].…”

“…The model actually yields predictions close to the current BICEP/Keck bounds [44], which can be improved with small corrections 3 to the potential during the last 60 efolds. Alternatively, if the resolution of the H 0 tension is Early Dark Energy (EDE) [45][46][47], the CMB fits need a slightly higher scalar spectral index n S ∼ 0.98 -0.995 [48][49][50], which is readily retrofitted by power law inflation. Interestingly, for the parameters which are close to the observationally favored values, the regime of universe self-reproduction in power law inflation is relegated to the cutoff physics, and so are superseded by the primordial bubble.…”