Linear seesaw model with hidden gauge symmetry

We propose a natural realization of a linear seesaw model with hidden gauge symmetry in which $SU(2{)}_L$ triplet fermions and one extra Higgs singlet, doublet, and quartet scalar are introduced. Small neutrino mass can be realized by two suppression factors that are the small vacuum expectation value of a quartet scalar and the inverse of a Dirac mass for the triplet. After formulating the neutrino mass matrix, we discuss the collider phenomenology of the model, focusing on signals from exotic charged particles production at the LHC.

Figure 1

(a) The cross section for pair production process $pp\to Z/\gamma \to {\phi }^{++}{\phi }^{--}$ and $pp\to Z/\gamma \to {\phi }_{1,2}^{+}{\phi }_{1,2}^{-}$ as a function of quartet mass $M_4$. (b) The cross section for pair production process $pp\to Z/\gamma \to {\mathrm{\Sigma }}^{+}{\mathrm{\Sigma }}^{-}({{\mathrm{\Sigma }}^{\prime }}^{+}{{\mathrm{\Sigma }}^{\prime }}^{-})$ as a function of triplet fermion mass $M_{\mathrm{\Sigma }}$.

Figure 2

(a) Branching ratio for decay of ${\phi }^{++}$ in quartet scalar. (b) Branching ratio for decay of ${\phi }_1^{+}$ in quartet scalar. They are given as a function of Yukawa coupling $y_L$, assuming one element is dominant and some parameters are fixed as indicated in the plots.