Neutrino cuboid for normal mass ordering and tribimaximal flavor mixing

Abstract

Given the latest JUNO implication for normal neutrino mass ordering, we parametrize three neutrino masses in a flavor cuboid: $m_1^{}=m_0^{}\sin \xi$, $m_2^{}=m_0^{}\cos \xi \sin \zeta$ and $m_3^{}=m_0^{}\cos \xi \cos \zeta$. We find that this cuboid is able to accommodate both neutrino mass degeneracy and tribimaximal flavor mixing in its cubic limit with ${\xi }_{\ast }^{}=\arctan \left(1/\sqrt{2}\right)\simeq 35.26^{\circ }$ and ${\zeta }_{\ast }^{}=45^{\circ }$. Assuming ${\theta }_{12}^{}=\xi$ and ${\theta }_{23}^{}=\zeta$ for the two large angles of neutrino oscillations and expanding them around ${\xi }_{\ast }^{}$ and ${\zeta }_{\ast }^{}$, we propose a viable ansatz which predicts a normal but nearly degenerate neutrino mass spectrum and a nearly tribimaximal neutrino mixing pattern. Testing the achieved correlation among ${\xi }_{\ast }^{}-{\theta }_{12}^{}$, ${\zeta }_{\ast }^{}-{\theta }_{23}^{}$ and $\Delta m_{21}^2/\Delta m_{31}^2$ will provide a smoking gun for the validity of this ansatz.

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