Flavour Covariant Transport Equations: an Application to Resonant Leptogenesis

By P. S. Bhupal Dev, Peter Millington, A. Pilaftsis, D. Teresi. 2014

178 citations recorded by the source corpus.

We present a fully flavour-covariant formalism for transport phenomena, by deriving Markovian master equations that describe the time-evolution of particle number densities in a statistical ensemble with arbitrary flavour content. As an application of this general formalism, we study flavour effects in a scenario of resonant leptogenesis (RL) and obtain the flavour-covariant evolution equations for heavy-neutrino and lepton number densities. This provides a complete and unified description of RL, capturing three distinct physical phenomena: (i) the resonant mixing between the heavy-neutrino states, (ii) coherent oscillations between different heavy-neutrino flavours, and (iii) quantum decoherence effects in the charged-lepton sector. To illustrate the importance of this formalism, we numerically solve the flavour-covariant rate equations for a minimal RL model and show that the total lepton asymmetry can be enhanced by up to one order of magnitude, as compared to that obtained from flavour-diagonal or partially flavour off-diagonal rate equations. Thus, the viable RL model parameter space is enlarged, thereby enhancing further the prospects of probing a common origin of neutrino masses and the baryon asymmetry in the Universe at the LHC, as well as in low-energy experiments searching for lepton flavour and number violation. The key new ingredients in our flavour-covariant formalism are rank-4 rate tensors, which are required for the consistency of our flavour-mixing treatment, as shown by an explicit calculation of the relevant transition amplitudes by generalizing the optical theorem. We also provide a geometric and physical interpretation of the heavy-neutrino degeneracy limits in the minimal RL scenario. Finally, we comment on the consistency of various suggested forms for the heavy-neutrino self-energy regulator in the lepton-number conserving limit.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/586a64a6cb9370f331530501cca93a33da192644

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In Nuclear and High Energy Physics

Citations in the corpus

A facility to search for hidden particles at the CERN SPS: the SHiP physics case (2015, methodology): “The inclusion of phenomena due to charged-lepton decoherence and heavy-neutrino flavour oscillations may increase the predictions for the BAU by up to one order of magnitude in RL models, according to a recent study based on a fully flavour-covariant formalism [699].”
A White Paper on keV sterile neutrino Dark Matter (2016, background): “In addition, the heavy singlet neutrinos in this model with a degenerate mass spectrum could be used to explain the observed matter-antimatter asymmetry in the Universe through the mechanism of resonant leptogenesis [393, 781, 782].”