Neutrinos may acquire small Dirac or Majorana masses by new low-energy physics in terms of the chiral gravitational anomaly, as proposed by Dvali and Funcke (2016). This model predicts fast neutrino decays, νi→νj+φ and νi→νj+φ, where the gravi-Majorons φ are pseudoscalar Nambu-Goldstone bosons. The final-state neutrino and antineutrino distributions differ depending on the Dirac or Majorana mass of the initial state. This opens a channel for distinguishing these cases, for example in the spectrum of high-energy astrophysical neutrinos. In particular, we put bounds on the neutrino lifetimes in the Majorana case, τ2/m2>1.1×10-3(6.7×10-4) s/eV and τ3/m3>2.2×10-5(1.3×10-4) s/eV at 90% CL for hierarchical (degenerate) masses, using data from experiments searching for antineutrino appearance from the Sun.
Distinguishing Dirac and Majorana neutrinos by their decays via Nambu-Goldstone bosons in the gravitational-anomaly model of neutrino masses
Vitagliano E.
2020
Abstract
Neutrinos may acquire small Dirac or Majorana masses by new low-energy physics in terms of the chiral gravitational anomaly, as proposed by Dvali and Funcke (2016). This model predicts fast neutrino decays, νi→νj+φ and νi→νj+φ, where the gravi-Majorons φ are pseudoscalar Nambu-Goldstone bosons. The final-state neutrino and antineutrino distributions differ depending on the Dirac or Majorana mass of the initial state. This opens a channel for distinguishing these cases, for example in the spectrum of high-energy astrophysical neutrinos. In particular, we put bounds on the neutrino lifetimes in the Majorana case, τ2/m2>1.1×10-3(6.7×10-4) s/eV and τ3/m3>2.2×10-5(1.3×10-4) s/eV at 90% CL for hierarchical (degenerate) masses, using data from experiments searching for antineutrino appearance from the Sun.Pubblicazioni consigliate
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