Prospects for strangelet detection with large-scale cosmic ray observatories

Quark matter which contains s-quarks in addition to u- and d- could be stable or metastable. In this case, lumps made of this strange matter, called strangelets, could occasionally hit the Earth. When travelling through the atmosphere they would behave not dissimilar to usual high-velocity meteors with only exception that, eventually, strangelets reach the surface. As these encounters are expected to be extremely rare events, very large exposure is needed for their observation. Fluorescence detectors utilized in large ultra-high energy cosmic ray observatories, such as the Pierre Auger observatory and the Telescope Array are well suited for a task of the detection of these events. The flux limits that can be obtained with the Telescope Array fluorescence detectors could be as low as $5\times 10^{-22}~cm^{-2}~s^{-1}~sr^{-1}$ which would improve by 1.5 orders of magnitude the strongest present limits obtained from ancient mica crystals.