Physical and Cosmological Implications of a Possible Class of Particles   Able to Travel Faster than Light
  If Lorentz invariance is only an approximate property of equations describing a sector of matter above some critical distance scale, the speed of light c will not necessarily be the only critical speed in vacuum. Superluminal sectors of matter may exist related to new degrees of freedom not yet discovered experimentally. The new particles would not be tachyons: they may feel different minkowskian space-times with critical speeds much higher than c and behave kinematically like ordinary particles apart from the difference in critical speed. We present a discussion of possible physical (theoretical and experimental) and cosmological implications of such a scenario, assuming that the superluminal sectors couple weakly to ordinary matter. 
Luis Gonzalez-Mestres (LPC College de France and LAPP Annecy)