Strangelets as cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff.

Strangelets (stable lumps of quark matter) can have masses and charges much higher than those of nuclei, but have very low charge-to-mass ratios. This is confirmed in a relativistic Thomas-Fermi model. The high charge allows astrophysical strangelet acceleration to energies orders of magnitude higher than for protons. In addition, strangelets are much less susceptible to the interactions with the cosmic microwave background that suppress the flux of cosmic ray protons and nuclei above energies of 10(19)-10(20) eV (the Greisen-Zatsepin-Kuzmin cutoff). This makes strangelets an interesting possibility for explaining ultrahigh energy cosmic rays.