Phenomenology of excited doubly charged heavy leptons at the LHC

We consider the production at the LHC of exotic composite leptons of charge $Q=+2e$. Such states are allowed in composite models that contain extended isospin multiplets (${I}_{W}=1$ and ${I}_{W}=3/2$). These doubly charged leptons couple with standard model (SM) fermions via gauge interactions, thereby delineating and restricting their possible decay channels. We discuss the production cross section at the LHC of ${L}^{++}(pp\ensuremath{\rightarrow}{L}^{++},{\ensuremath{\ell}}^{\ensuremath{-}})$ and concentrate on the leptonic signature deriving from the cascade decays ${L}^{++}\ensuremath{\rightarrow}{W}^{+}{\ensuremath{\ell}}^{+}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ i.e. $pp\ensuremath{\rightarrow}{\ensuremath{\ell}}^{\ensuremath{-}}({\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{+}){\ensuremath{\nu}}_{\ensuremath{\ell}}$ showing that the invariant mass distribution of the like-sign dilepton has a sharp end point corresponding to excited lepton mass ${m}^{*}$. We find that the $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$ run is sensitive at the 3-sigma (5-sigma) level to a mass of the order of 600 GeV if $L=10\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ ($L=20\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$). The $\sqrt{s}=14\text{ }\text{ }\mathrm{TeV}$ run can reach a sensitivity at 3-sigma (5-sigma) level up to ${m}^{*}=1\text{ }\text{ }\mathrm{TeV}$ for $L=20\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ ($L=60\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$).