Constraints on hadronic models in extensive air showers with the Pierre   Auger Observatory
  Extensive air showers initiated by ultra-high energy cosmic rays are sensitive to the details of hadronic interactions models, so we present the main results obtained using the data of the Pierre Auger Observatory. The depth at which the maximum of the electromagnetic development takes place is the most sensitive parameter to infer the nature of the cosmic rays. However, the hadronic models cannot describe consistently the maximum and the muon measurements at energies higher than those reached at the LHC. 
J. Espadanal (for the Pierre Auger Collaboration)
astro-ph.HE hep-ex hep-ph