Regular Article - Theoretical Physics
The hubble tension as a hint of leptogenesis and neutrino mass generation
Physik-Department, Technische Universität, München, James-Franck-Straße, 85748, Garching, Germany
2 Gravitation Astroparticle Physics Amsterdam (GRAPPA), Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
Accepted: 19 May 2021
Published online: 14 June 2021
The majoron, a neutrinophilic pseudo-Goldstone boson conventionally arising in the context of neutrino mass models, can damp neutrino free-streaming and inject additional energy density into neutrinos prior to recombination. The combination of these effects for an eV-scale mass majoron has been shown to ameliorate the outstanding tension, however only if one introduces additional dark radiation at the level of . We show here that models of low-scale leptogenesis can naturally source this dark radiation by generating a primordial population of majorons from the decays of GeV-scale sterile neutrinos in the early Universe. Using a posterior predictive distribution conditioned on Planck2018+BAO data, we show that the value of observed by the SHES collaboration is expected to occur at the level of in the primordial majoron cosmology (to be compared with in the case of CDM). This insight provides an intriguing connection between the neutrino mass mechanism, the baryon asymmetry of the Universe, and the discrepant measurements of .
© The Author(s) 2021
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