arXiv subjects

Andrea De Simone

Publications and source records attributed to Andrea De Simone.

57 records · Page 4Linked to original sources

arXiv2007

Quantum Boltzmann Equations and Leptogenesis

The closed time-path formalism is a powerful Green's function formulation to describe non-equilibrium phenomena in field theory and it leads to a complete non-equilibrium quantum kinetic theory. We make use of this formalism to write down the set of quantum Boltzmann equations relevant for leptogenesis. They manifest memory effects and off-shell corrections. In particular, memory effects lead to a time-dependent CP asymmetry whose value at a given instant of time depends upon the previous history of the system. This result is particularly relevant when the asymmetry is generated by the decays of nearly mass-degenerate heavy states, as in resonant or soft leptogenesis.

hep-ph↗

arXiv2007

On Resonant Leptogenesis

It has been recently shown that the quantum Boltzmann equations may be relevant for the leptogenesis scenario. In particular, they lead to a time-dependent CP asymmetry which depends upon the previous dynamics of the system. This memory effect in the CP asymmetry is particularly important in resonant leptogenesis where the asymmetry is generated by the decays of nearly mass-degenerate right-handed neutrinos. We study the impact of the nontrivial time evolution of the CP asymmetry in resonant leptogenesis, both in the one-flavour case and with flavour effects included. We show that significant qualitative and quantitative differences arise with respect to the case in which the time dependence of the CP asymmetry is neglected.

hep-ph↗

arXiv2007

On the Impact of Flavour Oscillations in Leptogenesis

When lepton flavour effects in thermal leptogenesis are active, they introduce important differences with respect to the case in which they are neglected, the so-called one-flavour approximation. We investigate analytically and numerically the transition from the one-flavour to the two-flavour case when the $τ$-lepton flavour becomes distinguishable from the other two flavours. We study the impact of the oscillations of the asymmetries in lepton flavour space on the final lepton asymmetries, for the hierarchical right-handed neutrino mass spectrum. Flavour oscillations project the lepton state on the flavour basis very efficiently. We conclude that flavour effects are relevant typically for $M_1\lsim 10^{12}$ GeV, where $M_1$ is the mass of the lightest right-handed neutrino.

hep-ph↗