The sensitivity of cosmic ray air shower experiments for excited lepton   detection
  In models with substructure in the fermionic sector, excited fermion states are expected. Excited leptons could be produced in the interaction of high energy quasi-horizontal cosmic neutrinos with the atmosphere via neutral and charged current processes, $\nu N \to \nu^* X$ and $\nu N \to \ell^* X$. The hadronic component X, and possibly part of the excited lepton decay products, would originate an extensive air shower, observable in large cosmic ray experiments. In this paper, the sensitivity of present and planned very high energy cosmic ray experiments to excited lepton production is estimated and discussed. 
M.C.Espirito Santo, M.Paulos, M.Pimenta, J.C.Romao, B.Tome