The Hubble Tension as a Hint of Leptogenesis and Neutrino Mass Generation. (arXiv:2103.03249v2 [hep-ph] UPDATED)
<a href="http://arxiv.org/find/hep-ph/1/au:+Escudero_M/0/1/0/all/0/1">Miguel Escudero</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Witte_S/0/1/0/all/0/1">Samuel J. Witte</a>
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 $H_0$ tension, however only if one introduces
additional dark radiation at the level of $Delta N_{rm eff} sim 0.5$. 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
$H_0$ observed by the SH$_0$ES collaboration is expected to occur at the level
of $sim 10%$ in the primordial majoron cosmology (to be compared with $sim
0.1%$ in the case of $Lambda$CDM). This insight provides an intriguing
connection between the neutrino mass mechanism, the baryon asymmetry of the
Universe, and the discrepant measurements of $H_0$.
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 $H_0$ tension, however only if one introduces
additional dark radiation at the level of $Delta N_{rm eff} sim 0.5$. 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
$H_0$ observed by the SH$_0$ES collaboration is expected to occur at the level
of $sim 10%$ in the primordial majoron cosmology (to be compared with $sim
0.1%$ in the case of $Lambda$CDM). This insight provides an intriguing
connection between the neutrino mass mechanism, the baryon asymmetry of the
Universe, and the discrepant measurements of $H_0$.
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