Chaos, Determinacy and Fractals in Active-Sterile Neutrino Oscillations in the Early Universe

Understand

The possibility of light sterile neutrinos allows for the resonant production of lepton number in the early universe through matter-affected neutrino mixing.

• For a given a mixing of the active and sterile neutrino states it has been found that the lepton number generation process is chaotic and strongly oscillatory.
• We undertake a new study of this process' sensitivity to initial conditions through the quantum rate equations.
• We confirm the chaoticity of the process in this solution, and moreover find that the resultant lepton number and the sign of the asymmetry produces a fractal in the parameter space of mass, mixing angle and initial baryon number.