Non-unitary neutrino mixing and CP violation in the minimal inverse seesaw model

TL;DR

This paper introduces a minimal inverse seesaw model with two pairs of singlet neutrinos to explain neutrino masses and mixing, highlighting its testability and potential for observing new CP violation effects.

Contribution

The paper proposes a simplified, minimal inverse seesaw model that is natural, testable, and predicts correlated non-unitary neutrino mixing parameters and CP violation effects.

Findings

Strong correlation of non-unitary mixing parameters.

Constraints on parameters from current experimental data.

Potential to observe new CP violation effects at neutrino factories.

Abstract

We propose a simplified version of the inverse seesaw model, in which only two pairs of the gauge-singlet neutrinos are introduced, to interpret the observed neutrino mass hierarchy and lepton flavor mixing at or below the TeV scale. This minimal inverse seesaw scenario (MISS) is technically natural and experimentally testable. In particular, we show that the effective parameters describing the non-unitary neutrino mixing matrix are strongly correlated in the MISS, and thus, their upper bounds can be constrained by current experimental data in a more restrictive way. The Jarlskog invariants of non-unitary CP violation are calculated, and the discovery potential of such new CP-violating effects in the near detector of a neutrino factory is discussed.