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A framework for testing leptonic unitarity by neutrino oscillation experiments

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Author(s):
Fong, Chee Sheng ; Minakata, Hisakazu ; Nunokawa, Hiroshi
Total Authors: 3
Document type: Journal article
Source: Journal of High Energy Physics; v. N/A, n. 2, p. 44-pg., 2017-02-22.
Abstract

If leptonic unitarity is violated by new physics at an energy scale much lower than the electroweak scale, which we call low-scale unitarity violation, it has different characteristic features from those expected in unitarity violation at high-energy scales. They include maintaining flavor universality and absence of zero-distance flavor transition. We present a framework for testing such unitarity violation at low energies by neutrino oscillation experiments. Starting from the unitary 3 active plus N (arbitrary positive integer) sterile neutrino model we show that by restricting the active-sterile and sterile sterile neutrino mass squared differences to greater than or similar to 0.1 eV(2) the oscillation probability in the (3 + N) model becomes insensitive to details of the sterile sector, providing a nearly model independent framework for testing low-scale unitarity violation. Yet, the presence of the sterile sector leaves trace as a constant probability leaking term, which distinguishes low scale unitarity violation from the high-scale one. The non-unitary mixing matrix in the active neutrino subspace is common for the both cases. We analyze how severely the unitarity violation can be constrained in ye-row by taking a JUNO-like setting to simulate medium baseline reactor experiments. Possible modification of the features of the (3 + N) model due to matter effect is discussed to first order in the matter potential. (AU)

FAPESP's process: 15/05208-4 - Physics of neutrinos
Grantee:Renata Zukanovich Funchal
Support Opportunities: Research Grants - Visiting Researcher Grant - International
FAPESP's process: 12/10995-7 - Particle physics phenomenology
Grantee:Gustavo Alberto Burdman
Support Opportunities: Research Projects - Thematic Grants