Some interesting phenomena observed in cosmic-ray experiments by means of X-ray emulsion technique at super accelerator energies

In the energy range above the PCR “knee” (5-1000 PeV), the emulsion chamber data exhibit some new features which are hard to explain in the framework of the Standard Model. In this survey the results of a systematic quest of some new and exotic types of events which are observed in the Pamir emulsion chamber experiment are presented, namely, huge “halo” events, coplanar events, penetrating hadrons with abnormally weak absorption in lead, “Centauro”-type events. Possible theoretical approaches for their explanation are discussed.