New cosmological bounds on hot relics: Axions $\&amp;$ Neutrinos

Giarè, William; Di Valentino, Eleonora; Melchiorri, Alessandro; Mena, Olga

doi:10.48550/arxiv.2011.14704

Cited by 5 publications

(7 citation statements)

References 95 publications

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“…[413] for a review). These particles may be copiously produced in the early Universe through either non-thermal mechanisms comprising CDM or thermal mechanisms which lead to a population of relativistic axions that would contribute to N eff [380,[414][415][416][417][418][419][420][421][422].…”

Section: Thermal Axionsmentioning

confidence: 99%

In the Realm of the Hubble tension $-$ a Review of Solutions

Di Valentino,

Mena,

Pan

et al. 2021

Preprint

Self Cite

178

252

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The simplest ΛCDM model provides a good fit to a large span of cosmological data but harbors large areas of phenomenology and ignorance. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the 4σ to 6σ disagreement between predictions of the Hubble constant, H 0 , made by the early time probes in concert with the "vanilla" ΛCDM Cosmological model, and a number of late time, model-independent determinations of H 0 from local measurements of distances and redshifts. The high precision and consistency of the data at both ends present strong challenges to the possible solution space and demands a hypothesis with enough rigor to explain multiple observations-whether these invoke new physics, unexpected large-scale structures or multiple, unrelated errors. A thorough review of the problem including a discussion of recent Hubble constant estimates and a summary of the proposed theoretical solutions is presented here. We include more than 850 references, indicating that the interest in this area has grown considerably just during the last few years. We classify the many proposals to resolve the tension in these categories: Early Dark Energy, Late Dark Energy, Dark energy models with 6 degrees of freedom and their extensions, Models with extra relativistic degrees of freedom, Models with Extra Interactions, Unified cosmologies, Modified gravity, Inflationary models, Modified recombination history, Physics of the critical Phenomena, and Alternative proposals. Some are formally successful, improving the fit to the data in light of their additional degrees of freedom, restoring agreement within 1 − 2σ between Planck 2018, using the Cosmic Microwave Background power spectra data, Baryon Acoustic Oscillations, Pantheon SN data, and R20, the latest SH0ES Team [2] measurement of the Hubble constant (H 0 = 73.2 ± 1.3 km s −1 Mpc −1 at 68% confidence level). However, there are many more unsuccessful models which leave the discrepancy well above the 3σ disagreement level. In many cases, reduced tension comes not simply from a change in the value of H 0 but also due to an increase in its uncertainty due to degeneracy with additional physics, complicating the picture and pointing to the need for additional probes. While no specific proposal makes a strong case for being highly likely or far better than all others, solutions involving early or dynamical dark energy, neutrino interactions, interacting cosmologies, primordial magnetic fields, and modified gravity provide the best options until a better alternative comes along.

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Section: Thermal Axionsmentioning

confidence: 99%

In the Realm of the Hubble tension $-$ a Review of Solutions

Di Valentino,

Mena,

Pan

et al. 2021

Preprint

Self Cite

178

252

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“…This leads to important differences with respect to previous work, which assumed KSVZ scattering rates (see e.g. [23][24][25]).…”

Section: A Interactions With Pionsmentioning

confidence: 70%

“…Second, on the astrophysical side, measurements of the cooling rates of certain white dwarfs (see e.g. [32,33]) and red giant stars (see [34][35][36]) appear to hint (at slightly more than 3σ) at a DFSZ axion 1 Recent works [24,25] fixed the axion-pion coupling according to the KSVZ scenario (and did not discuss production via leptons). Therefore, such bounds on the QCD axion mass cannot be applied to DFSZ scenarios (especially when correlating with the Xenon-1T excess).…”

Section: Introductionmentioning

confidence: 99%

“…For this to be the case, the axion mass m a should be larger than about ∼ 0.05 eV and correspondingly the axion decay constant f , that is the scale suppressing the axion couplings to SM fields, should be smaller than about 10 8 GeV. By using CMB data and focusing on pion scattering, strong constraints on the axion mass have already been derived in one class of axion models, the KSVZ scenario [20,21], where the QCD axion coupling to SM fermions is negligible, since it vanishes at tree level (see [18,19] for the original works, and [22][23][24][25] for recent updates using Planck 2013, 2015 and 2018 data, respectively).…”

Section: Introductionmentioning

confidence: 99%

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The DFSZ axion in the CMB

Ferreira,

Notari,

Rompineve

2020

Preprint

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We perform for the first time a dedicated analysis of cosmological constraints on DFSZ QCD axion models. Such constructions are especially interesting in light of the recent Xenon-1T excess and of hints from stellar cooling. In DFSZ models, for ma 0.1 eV, scatterings of pions and muons can produce a sizable cosmic background of thermal axions, that behave similarly to massive neutrinos. However, the pion coupling depends on the alignment between the vevs of two Higgs doublets, and can be significantly suppressed or enhanced with respect to the KSVZ scenario. Using the latest Planck and BAO data, we find ma ≤ 0.2 eV at 95% C.L., when the axion coupling to pions caπ is maximal. Constraints on ma, instead, can be significantly relaxed when caπ is small. In particular, we point out that in the so-called DFSZ-II model, where the axion coupling to leptons does not vanish simultaneously with caπ, production via muons gives ma ≤ 0.6 eV at 95% C.L., whereas in the DFSZ-I model bounds on ma can be fully lifted. We then combine cosmological data with recent hints of a DFSZ axion coupled to electrons from the Xenon-1T experiment, finding in this case that the axion mass is constrained to be in the window 0.07 eV ma 1.8 (0.3) eV for the DFSZ-I (DFSZ-II) model. A similar analysis with stellar cooling hints gives 3 meV ma 0.2 eV for DFSZ-II, while no constraint arises in the DFSZ-I case. Forthcoming CMB Stage 4 experiments will be able to further test such scenarios; for instance the Xenon-1T window should be fully probed at 2σ for a DFSZ-I axion.

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“…See Table 8 for all other benchmark parameter values. We show limits and forecasts [179] for CAST [180,181], IAXO [182], and various haloscopes [31,[183][184][185][186][187][188][189][190][191][192] (for ρ loc = 0.3 GeV/cm 3 ) as well as the bounds from hot dark matter constraints [193], energy loss arguments in SN1987A [13]. The preferred regions cold dark matter [194] in the realignment scenario, and with the latest cosmic string decay calculations [195] are also indicated as horizontal arrows.…”

Section: Summary Of Resultsmentioning

confidence: 99%

Axion Quasiparticles for Axion Dark Matter Detection

Schütte-Engel,

Marsh,

Millar

et al. 2021

Preprint

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It has been suggested that certain antiferromagnetic topological insulators contain axion quasiparticles (AQs), and that such materials could be used to detect axion dark matter (DM). The AQ is a longitudinal antiferromagnetic spin fluctuation coupled to the electromagnetic Chern-Simons term, which, in the presence of an applied magnetic field, leads to mass mixing between the AQ and the electric field. The electromagnetic boundary conditions and transmission and reflection coefficients are computed. A model for including losses into this system is presented, and the resulting linewidth is computed. It is shown how transmission spectroscopy can be used to measure the resonant frequencies and damping coefficients of the material, and demonstrate conclusively the existence of the AQ. The dispersion relation and boundary conditions permit resonant conversion of axion DM into THz photons in a material volume that is independent of the resonant frequency, which is tuneable via an applied magnetic field. A parameter study for axion DM detection is performed, computing boost amplitudes and bandwidths using realistic material properties including loss. The proposal could allow for detection of axion DM in the mass range between 1 and 10 meV using current and near future technology.

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New cosmological bounds on hot relics: Axions $\&$ Neutrinos

Cited by 5 publications

References 95 publications

In the Realm of the Hubble tension $-$ a Review of Solutions

In the Realm of the Hubble tension $-$ a Review of Solutions

The DFSZ axion in the CMB

Axion Quasiparticles for Axion Dark Matter Detection

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