Constraints on secret neutrino interactions after Planck

Abstract

(Abridged) Neutrino interactions beyond the standard model may affect the cosmological evolution and can be constrained through observations. We consider the possibility that neutrinos possess secret scalar or pseudoscalar interactions mediated by the Nambu-Goldstone boson of a still unknown spontaneously broken global $U(1)$ symmetry, as in, e.g. , Majoron models. In such scenarios, neutrinos still decouple at $T\simeq 1$ MeV, but become tightly coupled again ('recouple') at later stages of the cosmological evolution. We use available observations of CMB anisotropies, including Planck 2013 and the joint BICEP2/Planck 2015 data, to derive constraints on the quantity ${\gamma }_{\nu \nu }^4$, parameterizing the neutrino collision rate due to (pseudo)scalar interactions. We consider both a minimal extension of the standard $\Lambda$CDM model, and scenarios with extra relativistic species or non-vanishing tensors. We find a typical constraint ${\gamma }_{\nu \nu }^4<0.9\times 10^{-27}$ (95% C.L.), implying an upper limit on the redshift $z_{rec}$ of neutrino recoupling $<8500$. In the framework of Majoron models, the upper limit on ${\gamma }_{\nu \nu }$ roughly translates on a constraint $g<8.2\times 10^{-7}$ on the Majoron-neutrino coupling constant $g$. In general, the data show a weak ($\sim 1\sigma$) but intriguing preference for non-zero values of ${\gamma }_{\nu \nu }^4$, with best fits in the range ${\gamma }_{\nu \nu }^4=(0.15-0.35)\times 10^{-27}$, depending on the particular dataset. This is more evident when either observations from ACT and SPT are included, or the possibility of non-vanishing tensor modes is considered. In particular, for the minimal model $\Lambda$CDM +${\gamma }_{\nu \nu }$ and including the Planck 2013, ACT and SPT data, we report ${\gamma }_{\nu \nu }^4=(0.45_{-0.38}^{+0.15})\times 10^{-27}$ ($200<z_{rec}<5700$) at 68% confidence level.

19 pages, 7 figures, 3 tables. Replaced to match version accepted for pubblication in JCAP

References in corpus (19)

• Massive neutrinos and cosmology
• A Joint Analysis of BICEP2/Keck Array and Planck Data
• Neutrino mass from Cosmology
• Neutrinos help reconcile Planck measurements with both Early and Local Universe
• Cosmology with self-interacting sterile neutrinos and dark matter - A pseudoscalar model
• Relic Neutrinos, thermal axions and cosmology in early 2014
• Limits on Majoron-emitting double-beta decays of Xe-136 in the KamLAND-Zen experiment
• Sterile Neutrinos in Light of Recent Cosmological and Oscillation Data: a Multi-Flavor Scheme Approach
• No new cosmological concordance with massive sterile neutrinos
• Boltzmann hierarchy for interacting neutrinos I: formalism
• Sterile neutrinos help reconcile the observational results of primordial gravitational waves from Planck and BICEP2
• Cosmological lepton asymmetry with a nonzero mixing angle θ_{13}
• Light sterile neutrinos after BICEP-2
• Cosmological constraints on neutrinos after BICEP2
• Unveiling secret interactions among sterile neutrinos with big-bang nucleosynthesis
• Dark Radiation and interacting scenarios
• Search for Majoron-emitting modes of double-beta decay of ${}^{136}$Xe with EXO-200
• Neutrino constraints: what large-scale structure and CMB data are telling us?
• Robustness of cosmic neutrino background detection in the cosmic microwave background

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• Global view of neutrino interactions in cosmology: The freestreaming window as seen by Planck
• Light sterile neutrinos from a late phase transition
• Neutrino Masses from Low Scale Partial Compositeness
• Dark matter and observable Lepton Flavour Violation