Gauged $L_{\mu }$-$L_{\tau }$ Model with an Inverse Seesaw Mechanism for Neutrino Masses

Abstract

In this paper, we propose a $G_{L-R}\times U(1{)}_{L_{\mu }-L_{\tau }}$ gauge-symmetric model where $G_{L-R}$ is the left-right gauge symmetry and $L_i$ is the $i-$flavor lepton number. We use the spontaneous breaking (SSB) of $U(1{)}_{L_{\mu }-L_{\tau }}$ to explain two discrepancies in the standard model: muon anomalous magnetic moment and light neutrinos and its oscillations. The massive neutral gauge boson, $Z_{\mu \tau }$, arising from the SSB can provide additional contributions to the muon anomalous magnetic moment. In order to explain neutrino masses, we employ the low-energy inverse seesaw mechanism by adding three $G_{L-R}$ singlet fermions, $S_{e,\mu ,\tau }$. The light neutrino mass matrix from the inverse seesaw formula has a specific two-zero texture pattern referred in the literature as the Type-C two-zero texture due to the $U(1{)}_{L_{\mu }-L_{\tau }}$ symmetry. This allows us to predict the values of the CP-violating Dirac phase, Majorana phases, and the absolute value of light neutrino masses in terms of the precisely measured mixing angles and mass squared differences. The model accommodates a quasi-degenerate spectrum of neutrino masses with inverted ordering. The calculated best-fit value of ${\delta }_{CP}$ surprisingly matches with the current experimentally measured best-fit value of ${\delta }_{CP}$. At $1\sigma$, the measured value of ${\delta }_{CP}$ favors a ${\theta }_{23}>\pi /4$. At $1\sigma$, most of the parameter space is within the cosmological bound on the sum of neutrino mass and the bound on the effective Majorana mass from neutrinoless beta decay.

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