NEW MODELS FOR NEUTRON-STARS

We consider a new type of neutron star model (Q stars), in which high-density, electrically neutral baryonic matter is a coherent classical solution to an effective field theory of strong forces and is bound in the absence of gravity. This model allows massive compact objects, suggesting that Cygnus X-1 and LMC X-3 may not be black holes, and has no macroscopic minimum mass. Because laboratory experiments on ordinary nuclei do not constrain the properties of bulk baryon matter, there is a wide new range of theoretical possibilities for compact objects.