Relaxing Cosmological Neutrino Mass Bounds with Unstable Neutrinos

Abstract

At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model ($\Lambda$CDM), the Planck collaboration reports $\sum m_{\nu }<0.12\text{eV}$ at 95% CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe ${\tau }_{\nu }\lesssim t_U$, represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body decaying neutrinos into BSM particles are a promising option to relax cosmological neutrino mass bounds. We then build a simple extension of the type I seesaw scenario by adding one sterile state ${\nu }_4$ and a Goldstone boson $\varphi$, in which ${\nu }_i\to {\nu }_4\varphi$ decays can loosen the neutrino mass bounds up to $\sum m_{\nu }\sim 1\text{eV}$, without spoiling the light neutrino mass generation mechanism. Remarkably, this is possible for a large range of the right-handed neutrino masses, from the electroweak up to the GUT scale. We successfully implement this idea in the context of minimal neutrino mass models based on a $U(1{)}_{\mu -\tau }$ flavor symmetry, which are otherwise in tension with the current bound on $\sum m_{\nu }$.

22 pages, 8 figures, 2 tables, 7 appendices. v2: Matches published version. Minor upgrades: added appendix on BBN constraints on sterile neutrinos lighter than active neutrinos, added appendix discussing the potential amelioration of CMB neutrino decay bounds, refined discussion in Sec. 3. Results and conclusions remain unchanged. v3: fixed factor of 2 in Eqs A.4, A.6 and A.8

References in corpus (31)

• The DESI Experiment Part I: Science,Targeting, and Survey Design
• Massive neutrinos and cosmology
• The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview
• From the trees to the forest: a review of radiative neutrino mass models
• Cosmology With a Very Light $L_{\mu }-L_{\tau }$ Gauge Boson
• Light Sterile Neutrinos: Models and Phenomenology
• Limiting neutrino magnetic moments with Borexino Phase-II solar neutrino data
• Status of Oscillation plus Decay of Atmospheric and Long-Baseline Neutrinos
• Vanishing Minors in the Neutrino Mass Matrix from Abelian Gauge Symmetries
• Limits on Majoron-emitting double-beta decays of Xe-136 in the KamLAND-Zen experiment
• Testing decay of astrophysical neutrinos with incomplete information
• Thermalisation of sterile neutrinos in the early Universe in the 3+1 scheme with full mixing matrix
• Addendum to: Global constraints on absolute neutrino masses and their ordering
• Constraints on neutrino decay lifetime using long-baseline charged and neutral current data
• Bounds on light sterile neutrino mass and mixing from cosmology and laboratory searches
• Supernova Constraints on Massive (Pseudo)Scalar Coupling to Neutrinos
• A New Equation of State for Dark Energy Model
• 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
• Neutrino Masses from a Dark Neutrino Sector below the Electroweak Scale
• Visible Decay of Astrophysical Neutrinos at IceCube
• Discovering leptonic forces using non-conserved currents
• On the Impact of Neutrino Decays on the Supernova Neutronization-Burst Flux
• Dynamical Dark sectors and Neutrino masses and abundances
• Cosmological neutrino mass detection: The best probe of neutrino lifetime
• MeV-scale reheating temperature and cosmological production of light sterile neutrinos
• Neutrino Invisible Decay at DUNE: a multi-channel analysis
• Accurately Weighing Neutrinos with Cosmological Surveys
• Visible neutrino decay at DUNE
• New limits on neutrino decay from the Glashow resonance of high-energy cosmic neutrinos

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