Quantum Black Holes from Cosmic Rays
  We investigate the possibility for cosmic ray experiments to discover non-thermal small black holes with masses in the TeV range. Such black holes would result due to the impact between ultra high energy cosmic rays or neutrinos with nuclei from the upper atmosphere and decay instantaneously. They could be produced copiously if the Planck scale is in the few TeV region. As their masses are close to the Planck scale, these holes would typically decay into two particles emitted back-to-back. Depending on the angles between the emitted particles with respect to the center of mass direction of motion, it is possible for the simultaneous showers to be measured by the detectors. 
Xavier Calmet, Lauretiu Ioan Caramete, Octavian Micu
hep-ph