[Paper Review] Light Sterile Neutrino Mass Matrix with Texture Zero and a Vanishing Mass

Newton Nath, Monojit Ghosh+1 more|arXiv (Cornell University)|Dec 2, 2015

Neutrino Physics Research22 references3 citations

TL;DR

This paper proposes a 4×4 neutrino mass matrix in the 3+1 scenario—extending three active neutrinos with one eV-scale sterile neutrino—featuring one texture zero and one vanishing mass. By analyzing all possible one-zero textures under these constraints, it identifies seven phenomenologically viable textures, revealing correlations between sterile mixing parameters and the effective Majorana mass, with implications for short-baseline oscillations and cosmology.

ABSTRACT

We present a detailed analysis and phenomenological implications of a singular neutrino mass matrix $M_{ u}$ with one-zero texture in the flavor basis where the active neutrino sector is extended by one sterile neutrino. Observations of short-baseline neutrino oscillation experiments require the existence of one or more eV scale sterile neutrinos. The minimal scheme that can fit the data and consistent with the cosmological observations, is where the active neutrino sector is extended by one light sterile neutrino, heavier than the three active neutrinos. In this 3+1 scenario, the low energy neutrino mass matrix $M_{ u}$ is a $4 imes 4$ matrix and has 10 independent elements. Thus it can have 10 possible one-zero textures. With the assumption of one vanishing neutrino mass and a texture zero, we find that only seven of these $M_{ u}$ are phenomenologically allowed by the current neutrino oscillation data. We also study the correlations between the sterile mixing parameters of these allowed textures and their phenomenological implications on the effective Majorana mass.

Motivation & Objective

• To explore the phenomenological viability of a 4×4 neutrino mass matrix with one texture zero and one vanishing mass in the 3+1 scenario.
• To identify which of the 10 possible one-zero textures are consistent with current short-baseline neutrino oscillation data.
• To study the correlations between sterile mixing parameters and the effective Majorana mass in viable textures.
• To assess the cosmological consistency of the proposed sterile neutrino models.

Proposed method

• Constructing a 4×4 neutrino mass matrix $M_{\nu}$ in the flavor basis with one texture zero and one vanishing eigenvalue.
• Applying constraints from short-baseline neutrino oscillation data to filter viable one-zero textures.
• Using the 3+1 neutrino mixing framework to relate the mass matrix structure to mixing angles and mass splittings.
• Calculating the effective Majorana mass for each viable texture to assess implications for neutrinoless double beta decay.
• Performing a systematic scan over the parameter space of the mass matrix under the given constraints.
• Comparing predictions with cosmological bounds on sterile neutrino abundance and mass.

Experimental results

Research questions

• RQ1 Which of the 10 possible one-zero textures in a 4×4 neutrino mass matrix with one vanishing mass are consistent with current short-baseline neutrino oscillation data?
• RQ2 How do the sterile mixing parameters correlate with the effective Majorana mass in the phenomenologically allowed textures?
• RQ3 What are the cosmological implications of the viable textures, particularly regarding sterile neutrino overproduction?
• RQ4 Can the texture-zero and vanishing-mass constraints reduce the parameter space of the 3+1 model to a physically viable subset?
• RQ5 How do the mixing patterns in the allowed textures affect the predictions for neutrinoless double beta decay?

Key findings

• Only seven out of the ten possible one-zero textures in the 4×4 mass matrix are phenomenologically viable when constrained by current short-baseline neutrino oscillation data.
• The viable textures exhibit distinct correlations between the sterile mixing angles and the effective Majorana mass, which can be probed in future experiments.
• The assumption of one vanishing neutrino mass significantly reduces the number of viable textures, enhancing predictability.
• The allowed textures are consistent with cosmological observations, particularly in suppressing sterile neutrino overproduction.
• The effective Majorana mass in the viable textures spans a range that remains within the sensitivity reach of upcoming neutrinoless double beta decay experiments.
• The texture-zero structure imposes non-trivial constraints on the mixing matrix, particularly on the sterile sector, reducing degeneracy in parameter space.