Some implications of neutron mirror neutron oscillation

We comment on a recently discussed possibility of oscillations between neutrons and degenerate mirror neutrons in the context of mirror models for particles and forces. It has been noted by Bento and Berezhiani that if these oscillations occurred at a rate of tau(-1)(N N') similar to s(-1) it would help explain putative super GKZ cosmic ray events provided the temperature of the mirror radiation is similar to 0.3-0.4 times that of familiar cosmic microwave background radiation. We discuss how such oscillation time scales can be realized in mirror models and find that the simplest nonsupersymmetric model for this idea requires the existence of a low mass (30-3000 GeV) color triplet scalar or vector boson. A supersymmetric model, where this constraint can be avoided is severely constrained by the requirement of maintaining a cooler mirror sector. We also find that the reheat temperature after inflation in generic models that give fast n-n' oscillation be less than about 300 GeV in order to maintain the required relative coolness of the mirror sector. (c) 2005 Elsevier B.V. All rights reserved.