Post-Sphaleron Baryogenesis and an Upper Limit on the Neutron-Antineutron Oscillation Time

Understand

A recently proposed scenario for baryogenesis, called post--sphaleron baryogenesis (PSB) is discussed within a class of quark--lepton unified framework based on the gauge symmetry SU(2)_L x SU(2)_R x SU(4)_c realized in the multi--TeV scale.

• The baryon asymmetry of the universe in this model is produced below the electroweak phase transition temperature after the sphalerons have decoupled from the Hubble expansion.
• These models embed naturally the seesaw mechanism for neutrino masses, and predict color-sextet scalar particles in the TeV range which may be accessible to the LHC experiments.
• A necessary consequence of this scenario is the baryon number violating \Delta B=2 process of neutron--antineutron (n-\bar{n}) oscillations.