Neutrino masses and gauged $U(1{)}_{\ell }$ lepton number

Abstract

We investigate the tree-level neutrino mass generation in the gauged $U(1{)}_{\ell }$ lepton model recently proposed by us [arXiv:1805.10382]. With the addition of one Standard Model(SM) singlet, ${\varphi }_1(Y=0,\ell =1)$, and one SM triplet scalar, $T(Y=-1,\ell =0)$, realistic lepton masses can be accommodated. The resulting magnitude of neutrino mass is given by $\sim v_t^3/v_L^2$, where $v_t$ and $v_L$ are the vacuum expectation values of $T$ and ${\varphi }_1$, respectively, and it is automatically of the inverse see-saw type. Since $v_L$ is the lepton number violation scale we take it to be high, i.e. $\mathcal{O}\gtrsim (\text{mbox}TeV)$. Moreover, the induced lepton flavor violating processes and the phenomenology of the peculiar triplet are studied. An interesting bound, $0.1\lesssim v_t\lesssim 24.1$ GeV, is obtained when taking into account the neutrino mass generation, $Br(\mu \to e\gamma )$, and the limits from oblique parameters, $\Delta S$ and $\Delta T$. Collider phenomenology of the SM triplets is also discussed.

Comments: 29 pages, 7 figures, match the published version