Expectations for Neutron-Antineutron Oscillation Time from TeV Scale Baryogenesis

Abstract

A TeV scale extension of the standard model that incorporates the seesaw mechanism for neutrino masses along with quark-lepton unification is presented. It is shown that this model leads to the Delta B = 2 baryon number violating process of neutron-antineutron (n-(n) over bar) oscillation. The model has all the ingredients to generate the observed baryon asymmetry of the universe using the B-violating decay of a scalar field involved in the seesaw mechanism. The B-violating decay arises from the exchange of color sextet scalars which have TeV scale masses. Baryogenesis occurs below the sphaleron decoupling temperature and has been termed post-sphaleron baryogenesis. Here we show that the constraints of TeV scale baryogenesis, when combined with the neutrino oscillation data and restrictions from flavor changing neutral currents mediated by the colored scalars imply an upper limit on the n-(n) over bar oscillation time of 5 x 10(10) sec. regardless of the quark-lepton unification scale. If this scale is relatively low, in the (200-250) TeV range, tau(n-()n() over bar) is predicted to be less than 10(10) sec., which is accessible to the next generation of proposed experiments.