Is the Cosmic-Ray Centauro Quark-Matter Fireball Metastable?

Presentation made at the 26th International Cosmic Ray Conference, ICRC '99We discuss the possible metastability of the cosmic-ray Centauro quark-matter fireball in terms of the equalization of the quark-gluon and vacuum pressures and the radius of the fireball, as deduced from the calculated thermodynamic quantities. We obtain the bag-stability curves as a function of T, µq and the bag radius R and we find that the Centauro fireball is situated within one standard deviation from these curves. This fact, together with the very high baryon density and binding energy and the low entropy per baryon of the state, prompt us to conjecture that the Centauro fireball may possibly be a metastable state