Neutrino decays as a natural explanation of the neutrino mass tension

Abstract

A new tension is emerging between the tight cosmological upper bounds on the total neutrino mass ($\sum m_{\nu }\lesssim 0.06\mathrm{eV}$) and the lower limits from oscillation experiments, with potentially far-reaching implications for cosmology and particle physics. Neutrinos decaying into massless BSM particles with lifetimes ${\tau }_{\nu }\sim 0.01-1\mathrm{Gyr}$ represent a theoretically well-motivated mechanism to reconcile such measurements. Using DESI DR2 and CMB datasets, we show that such decays relax the bound on the total neutrino mass up to $\sum m_{\nu }<0.23\mathrm{eV}$ (95%), restoring full agreement with oscillation data. We also present the first late-time cosmological analysis of neutrino decays into lighter neutrinos in a manner consistent with the measured mass splittings. In contrast to the decays into massless BSM particles, we find that this scenario only marginally alleviates - or even tightens - the cosmological neutrino mass bounds, depending on the mass ordering.

5+4 pages, 7 figures, 1 table. Expanded discussion on goodness-of-fit and particle physics implications. v2 matches the published PRD version. Comments welcome!

References in corpus (31)

• Massive neutrinos and cosmology
• 2020 Global reassessment of the neutrino oscillation picture
• DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
• The $H_0$ Olympics: A fair ranking of proposed models
• The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters
• NuFit-6.0: Updated global analysis of three-flavor neutrino oscillations
• HMcode-2020: Improved modelling of non-linear cosmological power spectra with baryonic feedback
• The Atacama Cosmology Telescope: A Measurement of the DR6 CMB Lensing Power Spectrum and its Implications for Structure Growth
• CMB power spectra and cosmological parameters from Planck PR4 with CamSpec
• Direct neutrino-mass measurement based on 259 days of KATRIN data
• Massive Neutrinos in Cosmology: Analytic Solutions and Fluid Approximation
• Relaxing Cosmological Neutrino Mass Bounds with Unstable Neutrinos
• Massive neutrinos and cosmic composition
• Long Range Interactions in Cosmology: Implications for Neutrinos
• Are cosmological neutrinos free-streaming?
• Invisible neutrino decay in precision cosmology
• Determining the Neutrino Lifetime from Cosmology
• Revisiting cosmological bounds on radiative neutrino lifetime
• Time-varying neutrino mass from a supercooled phase transition: current cosmological constraints and impact on the ${\Omega }_m$-${\sigma }_8$ plane
• CONNECT: A neural network based framework for emulating cosmological observables and cosmological parameter inference
• Hints of dark matter-neutrino interactions in Lyman-$\alpha$ data
• How to relax the cosmological neutrino mass bound
• Reconstruction of the neutrino mass as a function of redshift
• Cosmological neutrino mass detection: The best probe of neutrino lifetime
• Cosmology with varying fundamental constants from hyperlight, coupled scalars
• What can CMB observations tell us about the neutrino distribution function?
• Euclid preparation. Sensitivity to neutrino parameters
• Dispu$\tau$able: the high cost of a low optical depth
• Revisiting the impact of neutrino mass hierarchies on neutrino mass constraints in light of recent DESI data
• Positive neutrino masses with DESI DR2 via matter conversion to dark energy
• Neutrino mass tension or suppressed growth rate of matter perturbations?