A new scheme for the neutrino collision term valid from light to heavy mediator regimes, with smooth transition as the universe cools, for scalar-mediated NSI in Dirac and Majorana cases.
Observational Constraints on Secret Neutrino Interactions from Big Bang Nucleosynthesis
5 Pith papers cite this work. Polarity classification is still indexing.
abstract
We investigate possible interactions between neutrinos and massive scalar bosons via $g^{}_{\phi} \overline{\nu} \nu \phi$ (or massive vector bosons via $g^{}_V \overline{\nu} \gamma^\mu \nu V^{}_\mu$) and explore the allowed parameter space of the coupling constant $g^{}_{\phi}$ (or $g^{}_V$) and the scalar (or vector) boson mass $m^{}_\phi$ (or $m^{}_V$) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of Big Bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on $g^{}_{\phi}$ and $m^{}_\phi$ in the scalar-boson case is rather weak, due to a small number of degrees of freedom. However, in the vector-boson case, the most stringent bound on the coupling $g^{}_V \lesssim 6\times 10^{-10}$ at $95~\%$ confidence level is obtained for $m^{}_V \simeq 1~{\rm MeV}$, while the bound becomes much weaker $g^{}_V \lesssim 8\times 10^{-6}$ for smaller masses $m^{}_V \lesssim 10^{-4}~{\rm MeV}$. Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.
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Ultralight scalar dark matter amplifies the lepton-flavor-violating muon-to-positron conversion rate via an effective Majorana mass m_μe, yielding new constraints on flavor-off-diagonal neutrino couplings from SINDRUM II, COMET, and Mu2e bounds.
Models scalar-mediated νSI on the DSNB in a full three-flavor PMNS framework for four coupling structures and projects 3σ sensitivities at JUNO, Hyper-Kamiokande-Gd, and DUNE reaching g∼10^{-8} for m_ϕ∼100-300 eV.
PBHs must exceed 10^9 g to affect BBN observables, yielding beta upper limits from 10^{-17} to 10^{-19} for masses 10^9-10^10 g, with public code provided.
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Towards a complete scheme of cosmological neutrino self-interactions: Collision term for a wide range of mediator masses
A new scheme for the neutrino collision term valid from light to heavy mediator regimes, with smooth transition as the universe cools, for scalar-mediated NSI in Dirac and Majorana cases.
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Amplifying muon-to-positron conversion in nuclei with ultralight dark matter
Ultralight scalar dark matter amplifies the lepton-flavor-violating muon-to-positron conversion rate via an effective Majorana mass m_μe, yielding new constraints on flavor-off-diagonal neutrino couplings from SINDRUM II, COMET, and Mu2e bounds.
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Diffuse Supernova Neutrinos with Secret Neutrino Interactions
Models scalar-mediated νSI on the DSNB in a full three-flavor PMNS framework for four coupling structures and projects 3σ sensitivities at JUNO, Hyper-Kamiokande-Gd, and DUNE reaching g∼10^{-8} for m_ϕ∼100-300 eV.
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Primordial Black Holes Evaporating before Big Bang Nucleosynthesis
PBHs must exceed 10^9 g to affect BBN observables, yielding beta upper limits from 10^{-17} to 10^{-19} for masses 10^9-10^10 g, with public code provided.
- Probing Scalar Non-Standard Neutrino Interactions using High-Energy Astrophysical Neutrinos