Additional Light Sterile Neutrinos and Cosmology

Abstract

Tantalizing cosmological and terrestrial evidence suggests the number of light neutrinos may be greater than 3, motivating a careful re-examination of cosmological bounds on extra light species. Big Bang Nucleosynthesis constrains the number of relativistic neutrino species present during nucleosynthesis, $N_{eff}^{BBN}$, while measurements of the CMB angular power spectrum constrain the effective energy density in relativistic neutrinos at the time of matter-radiation equality, $N_{eff}^{CMB}$. There are a number of scenarios where new sterile neutrino species may have different contributions to $\Delta N_{eff}^{BBN}$ and $\Delta N_{eff}^{CMB}$, for masses that may be relevant to reconciling cosmological constraints with various terrestrial claims of neutrino oscillations. We consider a scenario with two sterile neutrinos and explore whether partial thermalization of the sterile states can ease the tension between cosmological constraints on $N_{eff}^{BBN}$ and terrestrial data. We then investigate the effect of a non-zero neutrino mass on their contribution to the radiation abundance, finding reductions in $\Delta N_{eff}^{CMB}$ of more than 5% for neutrinos with masses above 0.5 eV. While the effects we investigate here could play a role, we nevertheless find that two additional light sterile neutrinos species cannot fit all the data at the 95% confidence level.

arXiv comment9 pages, 3 figures; Version accepted for publication in Phys. Rev. D

References in corpus (43)

• Evidence for Neutrino Oscillations from the Observation of Electron Anti-neutrinos in a Muon Anti-Neutrino Beam
• Sterile Neutrinos as Dark Matter
• The Reactor Antineutrino Anomaly
• Improved Predictions of Reactor Antineutrino Spectra
• Relic neutrino decoupling including flavour oscillations
• Measurement of the solar neutrino capture rate with gallium metal. III: Results for the 2002--2007 data-taking period
• Sterile Neutrino Hot, Warm, and Cold Dark Matter
• Reanalysis of the GALLEX solar neutrino flux and source experiments
• Event Excess in the MiniBooNE Search for ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ Oscillations
• Statistical Significance of the Gallium Anomaly
• Unexplained Excess of Electron-Like Events From a 1-GeV Neutrino Beam
• The primordial abundance of 4He: evidence for non-standard big bang nucleosynthesis
• Are there sterile neutrinos at the eV scale?
• Cosmological Constraints from Sunyaev-Zel'dovich-Selected Clusters with X-ray Observations in the First 178 Square Degrees of the South Pole Telescope Survey
• Sterile neutrino oscillations after first MiniBooNE results
• Sterile neutrinos with eV masses in cosmology -- how disfavoured exactly?
• A robust upper limit on N_eff from BBN, circa 2011
• Probing oscillations into sterile neutrinos with cosmology, astrophysics and experiments
• 3+1 and 3+2 Sterile Neutrino Fits
• A New Approach to Systematic Uncertainties and Self-Consistency in Helium Abundance Determinations
• Reconciling sterile neutrinos with big bang nucleosynthesis
• Studies of neutrino asymmetries generated by ordinary-sterile neutrino oscillations in the early universe and implications for big bang nucleosynthesis bounds
• Thermalisation of light sterile neutrinos in the early universe
• Refined Big Bang Nucleosynthesis Constraints on ${\Omega }_{Baryon}$ and $N_{\nu }$
• Explaining LSND by a decaying sterile neutrino
• Non-Thermal Dark Matter Mimicking An Additional Neutrino Species In The Early Universe
• A Search for Electron Antineutrino Appearance at the $\Delta m^2\sim$ 1 ${\mathrm{eV}}^2$ Scale
• Increasing the effective number of neutrinos with decaying particles
• Increasing Neff with particles in thermal equilibrium with neutrinos
• Sterile Neutrinos in Light of Recent Cosmological and Oscillation Data: a Multi-Flavor Scheme Approach
• An MCMC determination of the primordial helium abundance
• Light sterile neutrino production in the early universe with dynamical neutrino asymmetries
• Testing 3+1 and 3+2 neutrino mass models with cosmology and short baseline experiments
• Sterile Neutrinos and Light Dark Matter Save Each Other
• Dark Energy and Neutrino Masses from Future Measurements of the Expansion History and Growth of Structure
• Is cosmology compatible with sterile neutrinos?
• Sterile neutrino production via active-sterile oscillations: the quantum Zeno effect
• Simultaneous constraints on the number and mass of relativistic species
• Observational constraints on cosmic neutrinos and dark energy revisited
• Are Light Sterile Neutrinos Preferred or Disfavored by Cosmology?
• Testing standard and non-standard neutrino physics with cosmological data
• The ${\nu }_{\mu }\leftrightarrow {\nu }_s$ interpretation of the atmospheric neutrino data and cosmological constraints
• Hierarchical Four-Neutrino Oscillations With a Decay Option

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• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
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• A combined analysis of the $H_0$ late time direct measurements and the impact on the Dark Energy sector
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• Detecting non-relativistic cosmic neutrinos by capture on tritium: phenomenology and physics potential
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• Sterile Neutrinos with Secret Interactions - Lasting Friendship with Cosmology
• Phases of New Physics in the BAO Spectrum
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• Multi-momentum and multi-flavour active-sterile neutrino oscillations in the early universe: role of neutrino asymmetries and effects on nucleosynthesis
• $N_{\mathrm{eff}}$ in low-scale seesaw models versus the lightest neutrino mass
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• Constraints on active and sterile neutrinos in an interacting dark energy cosmology
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• Probing secret interactions of eV-scale sterile neutrinos with the diffuse supernova neutrino background
• Light sterile neutrino sensitivity at the nuSTORM facility
• Exploring neutrino mass and mass hierarchy in interacting dark energy models
• Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies
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• Cosmology-friendly time-varying neutrino masses via the sterile neutrino portal
• Hot thermal universe endowed with massive dark vector fields and the Hubble tension
• Twin Higgs Portal Dark Matter
• Cosmological evidence for leptonic asymmetry after Planck
• Low-scale seesaw models versus $N_{\mathrm{eff}}$
• Running vacuum in Brans-Dicke theory: a possible cure for the ${\sigma }_8$ and $H_0$ tensions
• Cosmological search for sterile neutrinos after Planck 2018
• A critical discussion on the $H_0$ tension
• Inflation, (P)reheating and Neutrino Anomalies: Production of Sterile Neutrinos with Secret Interactions
• More Is Different: Reconciling eV Sterile Neutrinos with Cosmological Mass Bounds
• Analysis of four-zero textures in $3+1$ framework
• Common Radiative Origin of Active and Sterile Neutrino Masses
• CP-violating Phases in Active-Sterile Solar Neutrino Oscillations
• Roles of sterile neutrinos in particle physics and cosmology
• Implications of Dynamical Dark Energy in the expansion of the Universe and the Structure Formation
• Neutrino oscillations in the presence of super-light sterile neutrinos
• Asymmetric dark matter and effective number of neutrinos
• Effects of active-sterile neutrino mixing during primordial nucleosynthesis
• Testing the coupling of dark radiations in light of the Hubble tension
• A Semiblind Reconstruction of the History of Effective Number of Neutrinos Using CMB Data
• Neutrinos in Astrophysics and Cosmology: Theoretical Advanced Study Institute (TASI) 2020 Lectures
• Cosmology in $R^2$-gravity: Effects of a Higher Derivative Scalar Condensate Background
• Dissecting the $H_0$ and $S_8$ tensions with Planck + BAO + supernova type Ia in multi-parameter cosmologies
• Sound Speed and Viscosity of Semi-Relativistic Relic Neutrinos