Improved cosmological constraints on the neutrino mass and lifetime. (arXiv:2112.13862v2 [hep-ph] UPDATED)
<a href="http://arxiv.org/find/hep-ph/1/au:+Abellan_G/0/1/0/all/0/1">Guillermo F. Abell&#xe1;n</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Chacko_Z/0/1/0/all/0/1">Zackaria Chacko</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Dev_A/0/1/0/all/0/1">Abhish Dev</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Du_P/0/1/0/all/0/1">Peizhi Du</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Poulin_V/0/1/0/all/0/1">Vivian Poulin</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Tsai_Y/0/1/0/all/0/1">Yuhsin Tsai</a>

We present cosmological constraints on the sum of neutrino masses as a
function of the neutrino lifetime, in a framework in which neutrinos decay into
dark radiation after becoming non-relativistic. We find that in this regime the
cosmic microwave background (CMB), baryonic acoustic oscillations (BAO) and
(uncalibrated) luminosity distance to supernovae from the Pantheon catalog
constrain the sum of neutrino masses $sum m_nu$ to obey $sum m_nu< 0.42$ eV
at (95$%$ C.L.). While the the bound has improved significantly as compared to
the limits on the same scenario from Planck 2015, it still represents a
significant relaxation of the constraints as compared to the stable neutrino
case. We show that most of the improvement can be traced to the more precise
measurements of low-$ell$ polarization data in Planck 2018, which leads to
tighter constraints on $tau_{rm reio}$ (and thereby on $A_s$), breaking the
degeneracy arising from the effect of (large) neutrino masses on the amplitude
of the CMB power spectrum.

We present cosmological constraints on the sum of neutrino masses as a
function of the neutrino lifetime, in a framework in which neutrinos decay into
dark radiation after becoming non-relativistic. We find that in this regime the
cosmic microwave background (CMB), baryonic acoustic oscillations (BAO) and
(uncalibrated) luminosity distance to supernovae from the Pantheon catalog
constrain the sum of neutrino masses $sum m_nu$ to obey $sum m_nu< 0.42$ eV
at (95$%$ C.L.). While the the bound has improved significantly as compared to
the limits on the same scenario from Planck 2015, it still represents a
significant relaxation of the constraints as compared to the stable neutrino
case. We show that most of the improvement can be traced to the more precise
measurements of low-$ell$ polarization data in Planck 2018, which leads to
tighter constraints on $tau_{rm reio}$ (and thereby on $A_s$), breaking the
degeneracy arising from the effect of (large) neutrino masses on the amplitude
of the CMB power spectrum.

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