It has been claimed recently that massive sterile neutrinos could bring about a new concordance between observations of the cosmic microwave background, the large-scale structure of the Universe, and local measurements of the Hubble constant, H(0). We demonstrate that this apparent concordance results from combining data sets which are in significant tension, even within this extended model, possibly indicating remaining systematic biases in the measurements. We further show that this tension remains when the cosmological model is further extended to include significant tensor modes, as suggested by the recent BICEP2 results. Using the Bayesian evidence, we show that the cold dark matter model with a cosmological constant is strongly favored over its neutrino extensions by various combinations of data sets. Robust data combinations yield stringent limits of ∑m(ν) ≲ 0.3 eV and m(ν,sterile)(eff) ≲ 0.3 eV at 95% C.L. for the sum of active and sterile neutrinos, respectively.
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http://dx.doi.org/10.1103/PhysRevLett.113.041301 | DOI Listing |
Phys Rev Lett
November 2024
Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Phys Rev Lett
November 2024
Department of Physics, University of California, San Diego, La Jolla, California 92093-0319, USA.
We present a mechanism for producing a cosmologically significant relic density of one or more sterile neutrinos. This scheme invokes two steps: First, a population of "heavy" sterile neutrinos is created by scattering-induced decoherence of active neutrinos. Second, this population is transferred, via sterile neutrino self-interaction-mediated scatterings and decays, to one or more lighter mass (∼10 keV to ∼1 GeV) sterile neutrinos that are far more weakly (or not at all) mixed with active species and could constitute dark matter.
View Article and Find Full Text PDFPhys Rev Lett
August 2024
Institute of High Energy Physics, Beijing.
This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158 days of detector operation, which contains 5.55×10^{6} reactor ν[over ¯]_{e} candidates identified as inverse beta-decay interactions followed by neutron capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties.
View Article and Find Full Text PDFPhys Rev Lett
May 2024
Berkeley Center for Theoretical Physics, University of California, Berkeley, California 94720, USA.
Phys Rev Lett
January 2024
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
With excellent energy resolution and ultralow-level radiogenic backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter (DM) models. In this work, we report new experimental limits on keV-scale sterile neutrino DM via the transition magnetic moment from conversion to active neutrinos ν_{s}→ν_{a}. We report new limits on fermionic dark matter absorption (χ+A→ν+A) and sub-GeV DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), and new exclusion limits for bosonic dark matter (axionlike particles and dark photons).
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