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arXiv · 2205.07353

Unstable Neutrinos can Relax Cosmological Mass Bounds

Stefan Sandner
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Abstract

The light neutrino masses are at present most stringently constraint via cosmological probes. In particular the Planck collaboration reports $ \sum m_ν\leq 0.12\,\mathrm{eV}$ at $95\%$ CL within the standard cosmological model. This is more than one order of magnitude stronger than the one arising from laboratory searches. The cosmological bound taken at face value excludes a plethora of neutrino flavour models which can successfully explain the neutrino oscillation data. The indirect nature of the cosmological bound, however, allows to relax the bound to up to $ \sum m_ν\sim 1\,\mathrm{eV}$ if neutrinos decay on timescales shorter than the age of the Universe, $τ_ν\leq t_U$. We present how a decay of the type $ν_i\toν_4ϕ$ can be realized within general models of the minimal extended seesaw framework. The idea is then explicitly realized within the context of a $U(1)_{μ-τ}$ flavour model.

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Stefan Sandner. 2022-05-15. Unstable Neutrinos can Relax Cosmological Mass Bounds. https://arxiv.org/abs/2205.07353

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