97-223 Luis Gonzalez-Mestres
Physical and cosmological implications of a possible class of particles able to travel faster than light (46K, LaTex) Apr 16, 97
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Abstract. The apparent Lorentz invariance of the laws of physics does not imply that space-time is indeed minkowskian. Matter made of solutions of Lorentz-invariant equations would feel a relativistic space-time even if the actual space-time had a quite different geometry (f.i. a galilean space-time). A typical example is provided by sine-Gordon solitons in a galilean world. A "sub-world" restricted to such solitons would be "relativistic", with the critical speed of solitons playing the role of the speed of light. Only the study of the deep structure of matter will unravel the actual geometry of space and time, which we expect to be scale-dependent and determined by the properties of matter itself. If Lorentz invariance is only an approximate property of equations describing a sector of matter at a given scale, an absolute frame (the "vacuum rest frame") may exist without contradicting the minkowskian structure of the space-time felt by ordinary particles. But c , the speed of light, will not necessarily be the only critical speed in vacuum: for instance, superluminal sectors of matter may exist related to new degrees of freedom not yet discovered experimentally. Such 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. Because of the very high critical speed in vacuum, superluminal particles will have very large rest energies. At speed v > c , they are expected to release "Cherenkov" radiation (ordinary particles) in vacuum. 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. The production of superluminal particles may yield clean signatures in experiments at very high energy accelerators. The breaking of Lorentz invariance will be basically a very high energy and very short distance phenomenon, not incompatible with the success of standard tests of relativity. Gravitation will undergo important modifications when extended to the superluminal sectors. The Big Bang scenario, as well as large scale structure, can be strongly influenced by the new particles. If superluminal particles exist, they could provide most of the cosmic (dark) matter and produce very high energy cosmic rays compatible with unexplained discoveries reported in the literature.

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