Superbradyons are a hypothetical class of superluminal particles. Unlike tachyons, they would have positive real values for both mass and energy. The term was suggested by Luis Gonzalez-Mestres as an antonym to bradyon (tardyon).
Reference
L. Gonzalez-Mestres, Superluminal Particles in Cosmic-Ray Physics, 26th International Cosmic Ray Conference, Salt Lake City, Utah, 1999.
External link
Superluminal Particles in Cosmic-Ray Physics