A modified Friedberg-Lee symmetry for the TM1 neutrino mixing

Abstract

In this letter, we put forward a special neutrino mass matrix which is invariant under a modified Friedberg-Lee (FL) transformation $\nu^{}_e \to \nu^{}_e-2\theta$ and $\nu^{}_{\mu, \tau} \to \nu^{}_{\mu, \tau}+\theta$ with $\theta$ being a space-time independent element of the Grassmann algebra. Compared to the original FL symmetry (with the transformation $\nu^{}_{e, \mu, \tau} \to \nu^{}_{e, \mu, \tau}+\theta$) which results in the TM2 neutrino mixing, the modified FL symmetry will lead us to the TM1 mixing which has a better agreement with the experimental results. While the original FL symmetry has to be broken in order to produce a realistic neutrino mass spectrum, the modified FL symmetry is allowed to remain intact and give us a vanishing $m^{}_1$. A combination of the FL symmetry with the $\mu$-$\tau$ reflection symmetry is also discussed.