Deep shower interpretation of the cosmic ray events observed in excess of the Greisen-Zatsepin-Kuzmin energy

We consider the possibility that the ultra-high-energy cosmic ray flux has a small component of exotic particles which create showers much deeper in the atmosphere than ordinary hadronic primaries. It is shown that applying the conventional AGASA/HiRes/Auger data analysis procedures to such exotic events results in large systematic biases in the energy spectrum measurement which may distort the shape of the measured spectrum near the expected Greisen-Zatsepin-Kuzmin (GZK) cutoff energy. Sub-GZK exotic showers may be misreconstructed with much higher energies and mimic super-GZK events. Alternatively, super-GZK exotic showers may elude detection by conventional fluorescence analysis techniques.