Neutrino oscillations and PMNS matrix in gauge-Higgs unification
Yutaka Hosotani
TL;DR
This work embeds neutrino oscillations in a GUT-inspired gauge-Higgs unification model in RS warped space, where Majorana masses on the UV brane induce an inverse seesaw that generates small neutrino masses. The PMNS matrix emerges from wavefunction overlaps, with three light states arising as eigenvalues of $F M$ and $U_{\rm PMNS}$ expressible via $\vec{p}_j = F^{-1/2} \vec{w}_j / \sqrt{n_j}$; in the diagonal-brane-mass case the framework yields a CP-conserving $U_{\rm PMNS}$ in the normal ordering that can accommodate $δ_{CP}=π$ as favored by NuFit-6.0. The model thus links high-scale UV-brane physics to low-energy neutrino data through a gauge-Higgs seesaw mechanism, while predicting no CP violation in this minimal setup and offering avenues to explore CP-violating effects via non-diagonal brane masses.
Abstract
In the $SO(5) \times U(1) \times SU(3)$ gauge-Higgs unification in the Randall-Sundrum (RS) warped space neutrino oscillations and the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix in the $W$ couplings originate from Majorana mass terms on the ultraviolet brane in the RS space. Tiny neutrino masses are generated by an inverse seesaw mechanism. The PMNS matrix in the normal ordering with $δ_{CP}=π$ naturally arises consistently with the NuFit-6.0 analysis of neutrino oscillation data.