A CMB search for the neutrino mass mechanism and its relation to the Hubble tension
Abstract
The majoron, a pseudo-Goldstone boson arising from the spontaneous breaking of global lepton number, is a generic feature of many models intended to explain the origin of the small neutrino masses. In this work, we investigate potential imprints in the cosmic microwave background (CMB) arising from massive majorons, should they thermalize with neutrinos after Big Bang Nucleosynthesis via inverse neutrino decays. We show that Planck2018 measurements of the CMB are currently sensitive to neutrino-majoron couplings as small as λ ∼10-13 , which if interpreted in the context of the type-I seesaw mechanism correspond to a lepton number symmetry breaking scale vL∼O (100 ) GeV . Additionally, we identify parameter space for which the majoron-neutrino interactions, collectively with an extra contribution to the effective number of relativistic species Neff, can ameliorate the outstanding H0 tension.
- Publication:
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European Physical Journal C
- Pub Date:
- April 2020
- DOI:
- 10.1140/epjc/s10052-020-7854-5
- arXiv:
- arXiv:1909.04044
- Bibcode:
- 2020EPJC...80..294E
- Keywords:
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- Astrophysics - Cosmology and Nongalactic Astrophysics;
- High Energy Physics - Experiment;
- High Energy Physics - Phenomenology
- E-Print:
- 5 pages, 2 figures + Supplementary Material. Comments are welcome! v2: Minor clarifications added. References added. Expanded Table 1 and moved it to the main text. Results and conclusions remain unchanged. Matches Letter published in EPJC. Ancillary file contains the obtained Planck legacy bound on neutrino-majoron interactions at 95%CL