REVIEW 9 cited by
Cosmology with varying fundamental constants from hyperlight, coupled scalars
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
abstract
The fundamental constants at recombination can differ from their present-day values due to degeneracies in cosmological parameters, raising the possibility of yet-undiscovered physics coupled directly to the Standard Model. We study the cosmology of theories in which a new, hyperlight scalar field modulates the electron mass and fine-structure constant at early times. We find new degeneracies in cosmologies that pair early recombination with a new contribution to the matter density arising at late times, whose predictions can be simultaneously consistent with CMB and low-redshift distance measurements. Such "late dark matter" already exists in the Standard Model in the form of massive neutrinos but is necessarily realized by the scalar responsible for shifting the early-time fundamental constants. After detailing the physical effects of varying constants and hyperlight scalar fields on cosmology, we show that variations of the electron mass and fine structure constant are constrained at the percent and permille level, respectively, and a hyperlight scalar in the mass range $10^{-32}~\mathrm{eV} \lesssim m_\phi \lesssim 10^{-28}~\mathrm{eV}$ can impact what variations are allowed while composing up to a percent of the present dark matter density. We comment on the potential for models with a varying electron mass to reconcile determinations of the Hubble constant from cosmological observations and distance-ladder methods, and we show that parameter inference varies significantly between recent baryon acoustic oscillation and type Ia supernova datasets.
Forward citations
Cited by 9 Pith papers
-
Correlated signals of ultralight scalar dark matter in pulsar timing
A finite-spatial-correlation Gaussian-field prior for PTA ULDM signals interpolates between fully correlated and uncorrelated limits and is validated on blinded mock data for linear and quadratic couplings.
-
Hubble tension: the shape wall
Late-time modifications to the expansion history can raise H0 by at most about 2% (conservative) to 3.7% (permissive) if the CMB acoustic scale is fixed.
-
The $H_0$ world cup. II. A comprehensive competition between proposed Hubble tension solutions
Against a common 2025-26 dataset (Planck PR4, ACT DR6, SPT-3G, DESI DR2, Pantheon+), early dark energy and early modified gravity models win the H0 competition (~3σ residual tension), while radiation and late-time sol...
-
Cosmological Concordance in an Especially Opaque Universe: A Tentative Cosmological Detection of Physical Neutrino Mass in $\Lambda$CDM
Imposing a high prior on τ = 0.11 ± 0.006 produces a 2σ positive neutrino mass sum of 0.10 eV and restores concordance between CMB and DESI data inside ΛCDM.
-
Searching for coupled, hyperlight scalars across cosmic history
Hyperlight quadratically coupled scalars making up a few percent of dark matter are bounded to near- or sub-gravitational couplings to electrons and photons over 10^-31 to 10^-28 eV, with quasar spectra setting the st...
-
The $H_0$ World Cup. I. Summary of the baseline group stage results
In a systematic head-to-head analysis, early dark energy and early modified gravity models reduce the Hubble tension to about 3σ and are favored over ΛCDM, while radiation and late-time alternatives are not.
-
An overview of what current data can (and cannot yet) say about evolving dark energy
The apparent preference for evolving dark energy depends strongly on which supernova catalog and which BAO survey are used, and is not robust across all independent data combinations.
-
The Hubble tension: A decade review
Pure early or late fixes to the Hubble tension are tightly constrained; remaining options are combined early-late interacting dark energy or new physics at the local-to-homogeneous transition.
-
Dark Energy and the Symbiosis Between Micro-physics and Cosmology (Naturally)
A review arguing that technical naturalness, powered by low-energy scale invariance and supersymmetric extra dimensions, is the most promising route to solving the cosmological constant problem.
Discussion (0). Continue with ORCID to comment.