Constraints on Neutrino Mass Ordering and Degeneracy from Planck and Neutrino-less Double Beta Decay

Abstract

We investigate constraints on neutrino mass ordering and degeneracy by considering the first cosmological result based on Planck measurements of the cosmic microwave background. It is shown that the result at 95% CL rejects a neutrino mass degeneracy larger than 85% (82.5%) for the normal (inverted) hierarchical case. We can also find some regions where the neutrino mass ordering will be able to be distinguished by combining a value of sum of the neutrino masses with an effective neutrino mass determined by neutrino-less double beta decay experiments. The results are obtained from the latest data of neutrino oscillation, cosmic microwave background, and the neutrino-less double beta decay experiments. These have significance in the discrimination of the neutrino mass ordering.

Neutrino mass limits: Robust information from the power spectrum of galaxy surveys

“…The bounds of 0.13 eV and 0.14 eV found in this work further support the conclusion of Ref. [77] and the constraints on the magnitude of degeneracy for neutrino masses. Moreover, Fig.…”

“…It was described in e.g., Ref. [76,77] how the constraints on M ν can provide information on the neutrino mass degeneracy. The authors concluded that a bound of M ν < 0.23 eV was able to reject at 95% C.L.…”

Present Status and Future Perspectives of the NEXT Experiment

“…| | is the effective Majorana mass defined in (2), and IH and NH stand for inverted and normal hierarchy, respectively. Adapted from [4]. long at 10 bar, tortuous due to multiple scattering, and with larger energy depositions at both ends (see Figure 3).…”

“…The negative results of EXO-200 and KamLAND-Zen indicate that the effective neutrino mass (the quantity measured in decays, as further discussed later in the text) must be smaller than 120-250 meV, where the mass range is due to uncertainties in the nuclear matrix elements. On the other hand, recent measurements of the cosmic microwave background (CMB) by the Planck experiment [3,4] yield an upper limit for the sum of the three light neutrino masses of 230 meV. The latter result excludes most of the so-called degenerate spectrum, in which the three neutrino masses are relatively large and similar to each other.…”

Effects on sinθ_{12} from perturbation of the neutrino mixing matrix with the partially degenerated neutrino masses

“…[1,2] for recent reviews, Refs. [3,4,5] for combined studies with cosmological observations, and Refs. [6,7] for previous works.…”