Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Detecting the Neutrinos Mass Hierarchy from Cosmological Data

Lixin Xu, Qing-Guo Huang

TL;DR

This work proposes a new dimensionless hierarchy parameter $Δ=(m_3-m_1)/(m_1+m_3)$ that unifies the normal and inverted neutrino mass hierarchies using oscillation data. The authors modify CAMB to include $Δ$ and perform a joint cosmological analysis with Planck 2015, BAO, SN, and HST data, deriving constraints on $Δ$ and the derived neutrino masses. They find cosmology is largely driven by the total neutrino mass, with the normal hierarchy mildly favored and specific 95% CL bounds: $m^{NH}_{ν, ext{min}}<0.030$ eV, $m^{IH}_{ν, ext{min}}<0.024$ eV, and $∑_ν m_ν<0.119$ eV (NH) or $0.135$ eV (IH). The proposed parametrization provides a cohesive framework for incorporating oscillation results into cosmological analyses and highlights the data required to decisively resolve the hierarchy in the future.

Abstract

We propose a new parameterization to measure the neutrino mass hierarchy, namely $Δ=(m_3-m_1)/(m_1+m_3)$ which is dimensionless and varies in the range $[-1,1]$. Taking into account the results of neutrino oscillation experiments, $Δ$ is the unique parameter for determining all the masses of neutrinos, and a positive (negative) sign of $Δ$ denotes the normal (inverted) mass hierarchy. Adopting the currently available cosmic observations, we find that the normal mass hierarchy is slightly favored, and the mass of lightest neutrino is less than $0.030$ eV for the normal mass hierarchy and $0.024$ eV for the inverted mass hierarchy at $95\%$ confidence level.

Detecting the Neutrinos Mass Hierarchy from Cosmological Data

TL;DR

This work proposes a new dimensionless hierarchy parameter that unifies the normal and inverted neutrino mass hierarchies using oscillation data. The authors modify CAMB to include and perform a joint cosmological analysis with Planck 2015, BAO, SN, and HST data, deriving constraints on and the derived neutrino masses. They find cosmology is largely driven by the total neutrino mass, with the normal hierarchy mildly favored and specific 95% CL bounds: eV, eV, and eV (NH) or eV (IH). The proposed parametrization provides a cohesive framework for incorporating oscillation results into cosmological analyses and highlights the data required to decisively resolve the hierarchy in the future.

Abstract

We propose a new parameterization to measure the neutrino mass hierarchy, namely which is dimensionless and varies in the range . Taking into account the results of neutrino oscillation experiments, is the unique parameter for determining all the masses of neutrinos, and a positive (negative) sign of denotes the normal (inverted) mass hierarchy. Adopting the currently available cosmic observations, we find that the normal mass hierarchy is slightly favored, and the mass of lightest neutrino is less than eV for the normal mass hierarchy and eV for the inverted mass hierarchy at confidence level.

Paper Structure

This paper contains 3 sections, 6 equations, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Hierarchy Parameter $\Delta$ Effects on CMB and Matter Power Spectra and the Fitting Results
  3. Conclusion

Figures (4)

  • Figure 1: The total neutrino mass.
  • Figure 2: The effects of hierarchy parameter $\Delta$ on the CMB TT, TE and EE power spectra from the top to the bottom respectively.
  • Figure 3: The effects of hierarchy parameter $\Delta$ on the matter power spectrum at $z=0$.
  • Figure 4: The 1D marginalized distribution and 2D contours for interested model parameters with $68\%$ and $95\%$ confidence levels.