Leptogenesis from Quantum Interference in a Thermal Bath

TL;DR

This paper presents a comprehensive quantum mechanical calculation of leptogenesis, revealing significant uncertainties in traditional methods and emphasizing the importance of thermal effects and Green's functions in explaining matter-antimatter asymmetry.

Contribution

It introduces a full quantum approach using Kadanoff-Baym equations to calculate lepton asymmetry without relying on number densities, highlighting the impact of thermal damping.

Findings

Quantum calculations show at least an order of magnitude uncertainty in conventional leptogenesis.

Thermal damping rates significantly affect the generated lepton asymmetry.

Green's functions provide a direct way to compute asymmetry without number density assumptions.

Abstract

Thermal leptogenesis explains the observed matter-antimatter asymmetry of the universe in terms of neutrino masses, consistent with neutrino oscillation experiments. We present a full quantum mechanical calculation of the generated lepton asymmetry based on Kadanoff-Baym equations. Origin of the asymmetry is the departure of the statistical propagator of the heavy Majorana neutrino from the equilibrium propagator, together with CP violating couplings. The lepton asymmetry is calculated directly in terms of Green's functions without referring to `number densities'. A detailed comparison with Boltzmann equations shows that conventional leptogenesis calculations have an uncertainty of at least one order of magnitude. Particularly important is the inclusion of thermal damping rates in the full quantum mechanical calculation.