First Detection of the Acoustic Oscillation Phase Shift Expected from the Cosmic Neutrino Background

Follin, Brent; Knox, L.; Millea, M.; Pan, Zhen

doi:10.1103/physrevlett.115.091301

Cited by 165 publications

(202 citation statements)

References 12 publications

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“…In contrast, the precise value of the vector masses and Yukawa couplings in the L 4 model can change the results considerably, as it is already clear from Eq. (10). When the vector-like masses are around the TeV scale or above, the models are excluded, while M 500 GeV yields predictions that are consistent with current data, as shown in Fig.…”

Section: A Massless Degrees Of Freedomsupporting

confidence: 75%

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Solving the Hierarchy Problem at Reheating with a Large Number of Degrees of Freedom

et al. 2016

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We present a new solution to the electroweak hierarchy problem. We introduce N copies of the Standard Model with varying values of the Higgs mass parameter. This generically yields a sector whose weak scale is parametrically removed from the cutoff by a factor of 1/ √ N . Ensuring that reheating deposits a majority of the total energy density into this lightest sector requires a modification of the standard cosmological history, providing a powerful probe of the mechanism. Current and near-future experiments will explore much of the natural parameter space. Furthermore, supersymmetric completions which preserve grand unification predict superpartners with mass below mW × M pl /MGUT ∼ 10 TeV.

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Section: A Massless Degrees Of Freedomsupporting

confidence: 75%

“…Until recently it was impossible to distinguish between the two types of radiation, as they affect the CMB damping tail in the same way [9]. The detection of a phase shift in the CMB anisotropies [10] has broken this degeneracy, and it is now possible to set a 95% C.L. bound: N fluid 1…”

Section: A Massless Degrees Of Freedommentioning

confidence: 99%

Solving the Hierarchy Problem at Reheating with a Large Number of Degrees of Freedom

et al. 2016

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“…Their imprints on the CMB peaks are hence different -the DA is expected to cause its largest change to the CMB close to the first peak in the TT spectrum based on Refs. [17,33], while N eff is not only constrained by matter-radiation equality, but also through its effect on the higher peaks in the CMB TT spectrum [34]. These distinct effects on the CMB imply that the DA model cannot be quantified by N eff , nor be restricted by N eff constraints.…”

Section: Discussionmentioning

confidence: 99%

Thermal friction as a solution to the Hubble tension

2020

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The phenomenological early dark energy (EDE) provides a promising solution to the Hubble tension in the form of an extra beyond-ΛCDM component that acts like a cosmological constant at early times (z ≥ 3000) and then dilutes away as radiation or faster. We show that a rolling axion coupled to a non-Abelian gauge group, which we call the 'dissipative axion' (DA), mimics this phenomenological EDE at the background level and presents a particle-physics model solution to the Hubble tension, while also eliminating fine-tuning in the choice of scalar-field potential. We compare the DA model to the EDE fluid approximation at the background level and comment on their similarities and differences. We determine that CMB observables sensitive only to the background evolution of the Universe are expected to be similar in the two models, strengthening the case for exploring the perturbations of the DA as well as for this model to provide a viable solution to the Hubble tension.1 The IR potential from the confining group is rapidly suppressed at temperatures above the confining scale and we have checked that its contribution is sub-dominant for our parameters.

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“…The unavoidable altering of θ d /θ s , in the case of ΛCDM+N eff is one of two main reasons the CMB data do not prefer larger values of N eff . The other is the shift in the temporal phase of the acoustic oscillations and the associated shifts in acoustic peak and trough locations [67,68].…”

Section: Additional Thermal Relativistic Speciesmentioning

confidence: 99%

Hubble constant hunter’s guide

2020

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Measurements of the Hubble constant, and more generally measurements of the expansion rate and distances over the interval 0 < z < 1, appear to be inconsistent with the predictions of the standard cosmological model (ΛCDM) given observations of cosmic microwave background temperature and polarization anisotropies. Here we consider a variety of types of departures from ΛCDM that could, in principle, restore concordance among these datasets, and we explain why we find almost all of them unlikely to be successful. We single out the set of solutions that increase the expansion rate in the decade of scale factor expansion just prior to recombination as the least unlikely. These solutions are themselves tightly constrained by their impact on photon diffusion and on the gravitational driving of acoustic oscillations of the modes that begin oscillating during this epoch -modes that project on to angular scales that are very well measured. We point out that a general feature of such solutions is a residual to fits to ΛCDM, like the one observed in Planck power spectra. This residual drives the modestly significant inferences of angular-scale dependence to the matter density and anomalously high lensing power, puzzling aspects of a data set that is otherwise extremely well fit by ΛCDM. I. INTRODUCTIONEstimates of the Hubble constant from a distance ladder approach are generally higher than those derived from cosmic microwave background (CMB) data, assuming the standard "ΛCDM" cosmological model [2]. The SH 0 ES team calibrates a supernova sample with Cepheids and finds H 0 = 74.03 ± 1.42 km/s/Mpc [3, hereafter R19].Compared with the value inferred from Planck CMB temperature and polarization power spectra plus CMB lensing, assuming ΛCDM, H 0 = 67.27 ± 0.60 km/s/Mpc, there is a 4.4 σ discrepancy. The most recent result from strong-lensing time delays, from the H 0 LiCoW team [4,5], assuming the standard cosmological model and a prior of Ω m ∈ [0.05, 0.5], of H 0 = 76.8 ± 2.5 km/s/Mpc is consistent with R19 and discrepant with the ΛCDM Planck value at 3.1 σ. The Carnegie-Chicago Hubble Project have used their own Hubble flow set of supernovae that they have calibrated with the tip of the red giant branch method. They find H 0 = 69.8 ± 0.8(stat) ± 1.7(sys) km/s/Mpc [6], which at the 2 σ level is consistent with all of these results.Bernal et al. [7] showed that in addition to a discrepancy in the Hubble constant, there is a discrepancy in the comoving sound horizon at the end of the baryon drag epoch, r drag s . They used Cepheid-calibrated supernovae [8,9] to infer distances out to redshifts with precise measurements of the baryon acoustic oscillation feature [10][11][12]. With these distances, they could convert the BAO angles to inferences of r drag s . Using supernova data to control the shape of D(z) they obtained relatively model-independent inferences of this empirically- * with apologies to Gunion et al. [1]

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First Detection of the Acoustic Oscillation Phase Shift Expected from the Cosmic Neutrino Background

Cited by 165 publications

References 12 publications

Solving the Hierarchy Problem at Reheating with a Large Number of Degrees of Freedom

Solving the Hierarchy Problem at Reheating with a Large Number of Degrees of Freedom

Thermal friction as a solution to the Hubble tension

Hubble constant hunter’s guide

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