TeV scale seesaw model and a flavorfulZ′at the LHC

Abstract

Small neutrino masses and their large mixing angles can be generated at the TeV scale by augmenting the standard model with an additional generation-dependent, anomaly-free $U(1{)}_{\ensuremath{\nu}}$ symmetry, in the presence of three right-handed neutrinos. The ${Z}^{\ensuremath{'}}$ gauge boson associated with the breaking of the $U(1{)}_{\ensuremath{\nu}}$ symmetry can be produced at the LHC. The flavorful nature of the ${Z}^{\ensuremath{'}}$ can be established by measuring its nonuniversal couplings to the charged leptons as determined by the lepton's $U(1{)}_{\ensuremath{\nu}}$ charges, which also govern the neutrino flavor structure. While the LHC has the potential of discovering the ${Z}^{\ensuremath{'}}$ up to ${M}_{{Z}^{\ensuremath{'}}}=4.5\text{ }\text{ }\mathrm{TeV}$ with $100\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ data at the center of mass energy $\sqrt{s}=14\text{ }\text{ }\mathrm{TeV}$, to establish the flavorful nature of the ${Z}^{\ensuremath{'}}$ requires much higher integrated luminosity. For our benchmark parameters that are consistent with neutrino oscillation data, at $\sqrt{s}=14\text{ }\text{ }\mathrm{TeV}$, a $5\ensuremath{\sigma}$ distinction between the dielectron and dimuon channels for ${M}_{{Z}^{\ensuremath{'}}}=3\text{ }\text{ }\mathrm{TeV}$ requires $500\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data. We find that the forward backward asymmetry distributions can also be useful in distinguishing the dielectron and dimuon channels in the low invariant mass and transverse momentum regions.