Cosmic neutrino background detection in large-neutrino-mass cosmologies

Alvey, James; Escudero, Miguel; Schwetz, Thomas

doi:10.1103/physrevd.105.063501

Cited by 31 publications

(21 citation statements)

References 70 publications

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“…As such, we could imagine a PTOLEMY-like experiment being used as a sort of model discriminator, in conjunction with facilities such as KATRIN and DESI/EUCLID, looking for cosmologically sound scenarios with large neutrino masses and/or non-standard neutrino distribution functions. This is exactly the sort of exciting experimental scenario we develop and explore in our companion work [36], where we show that there are improved detection prospects at a PTOLEMY-style experiment for large neutrino mass cosmologies, fully consistent with all current cosmological data.…”

Section: Discussionsupporting

confidence: 53%

“…In the more general context highlighted throughout this paper, however, we can immediately see that a KATRIN detection and a CMB-based bound can be in complete agreement provided that the neutrinos have a number density that is lower than that in ΛCDM. This plausible experimental scenario would have important implications for neutrinos in cosmology, see [36].…”

Section: Discussionmentioning

confidence: 97%

“…DESI [71] and EU-CLID [72]). A full exploration of the interplay between these probes is beyond the scope of this outlook, however, we discuss exactly this aspect in our companion paper [36]. Direct measurements of the absolute scale of the neutrino mass are perhaps the easiest to understand in terms of the potential for seemingly inconsistent experimental results.…”

Section: Discussionmentioning

confidence: 99%

“…VII, we briefly comment on the potential implications of the neutrino distribution function for measurements of the matter power spectrum with future galaxy surveys. Moreover, we motivate the physics case of searches for nonstandard neutrino populations at future terrestrial neutrino experiments, such as PTOLEMY, which we discuss in depth in our companion paper [36]. Technical details and supplementary results as part of our analysis are provided in the Appendices A−C.…”

Section: Introductionmentioning

confidence: 99%

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What can CMB observations tell us about the neutrino distribution function?

Alvey,

Escudero,

Sabti

2021

Preprint

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Cosmic Microwave Background (CMB) observations have been used extensively to constrain key properties of neutrinos, such as their mass. However, these inferences are typically dependent on assumptions about the cosmological model, and in particular upon the distribution function of neutrinos in the early Universe. In this paper, we aim to assess the full extent to which CMB experiments are sensitive to the shape of the neutrino distribution. We demonstrate that Planck and CMB-S4-like experiments have no prospects for detecting particular features in the distribution function. Consequently, we take a general approach and marginalise completely over the form of the neutrino distribution to derive constraints on the relativistic and non-relativistic neutrino energy densities, characterised by N eff = 3.0 ± 0.4 and ρ NR ν,0 < 14 eV cm −3 at 95% CL, respectively. The fact that these are the only neutrino properties that CMB data can constrain has important implications for neutrino mass limits from cosmology. Specifically, in contrast to the ΛCDM case where CMB and BAO data tightly constrain the sum of neutrinos masses to be mν < 0.12 eV, we explicitly show that neutrino masses as large as mν ∼ 3 eV are perfectly consistent with this data. Importantly, for this to be the case, the neutrino number density should be suitably small such that the bound on ρ NR ν,0 = mν nν,0 is still satisfied. We conclude by giving an outlook on the opportunities that may arise from other complementary experimental probes, such as galaxy surveys, neutrino mass experiments and facilities designed to directly detect the cosmic neutrino background.GitHub: Parameter files for MCMC analysis and code to reproduce all plots can be found here.

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Section: Discussionsupporting

confidence: 53%

Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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What can CMB observations tell us about the neutrino distribution function?

Alvey,

Escudero,

Sabti

2021

Preprint

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“…The upper bound m ν 0.1 eV has been derived previously such that ∆L = 2 processes do not suppress the generated asymmetry [5,6]. While cosmological bounds give approximately the same bound [7], nonstandard cosmology [8] can still allow for large m ν ∼ O(1) eV [9].…”

Section: Introductionmentioning

confidence: 90%

Rescuing High-Scale Leptogenesis using Primordial Black Holes

Bernal,

Fong,

Perez-Gonzalez

et al. 2022

Preprint

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We explore the interplay between light primordial black holes (PBH) and highscale baryogenesis, with a particular emphasis on leptogenesis. We first review a generic baryogenesis scenario where a heavy particle, X, with mass, M X , produced solely from PBH evaporation decays to generate a baryon asymmetry. We show that the viable parameter space is bounded from above by M X 10 17 GeV and increases with decreasing M X . We demonstrate that regions of the leptogenesis parameter space, where the lightest right-handed neutrino (RHN) mass M N 1 10 15 GeV and neutrino mass scale m ν 0.1 eV, excluded in standard cosmology due to ∆L = 2 washout processes, becomes viable with the assistance of light PBHs. This scenario of PBH-assisted leptogenesis occurs because the PBHs radiate RHNs via Hawking evaporation late in the Universe's evolution when the temperature of the thermal plasma is low relative to the RHN mass. Subsequently, these RHNs can decay and produce a lepton asymmetry while the washout processes are suppressed.

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A seesaw model for large neutrino masses in concordance with cosmology

Escudero

Schwetz

Terol-Calvo

2023

J. High Energ. Phys.

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Cosmological constraints on the sum of the neutrino masses can be relaxed if the number density of active neutrinos is reduced compared to the standard scenario, while at the same time keeping the effective number of neutrino species Neff ≈ 3 by introducing a new component of dark radiation. We discuss a UV complete model to realise this idea, which simultaneously provides neutrino masses via the seesaw mechanism. It is based on a U(1) symmetry in the dark sector, which can be either gauged or global. In addition to heavy seesaw neutrinos, we need to introduce 𝒪(10) generations of massless sterile neutrinos providing the dark radiation. Then we can accommodate active neutrino masses with ∑mν ~ 1 eV, in the sensitivity range of the KATRIN experiment. We discuss the phenomenology of the model and identify the allowed parameter space. We argue that the gauged version of the model is preferred, and in this case the typical energy scale of the model is in the 10 MeV to few GeV range.

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Cosmic neutrino background detection in large-neutrino-mass cosmologies

Cited by 31 publications

References 70 publications

What can CMB observations tell us about the neutrino distribution function?

What can CMB observations tell us about the neutrino distribution function?

Rescuing High-Scale Leptogenesis using Primordial Black Holes

A seesaw model for large neutrino masses in concordance with cosmology

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