Leptogenesis from Quantum Interference in a Thermal Bath

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 1 order of magnitude. Particularly important is the inclusion of thermal damping rates in the full quantum mechanical calculation.

Flavoured quantum Boltzmann equations from cQPA

“…fields whose mass-eigenstates do not coincide with interaction eigenstates. This certainly is the case for neutrino oscillations in the early universe [7], electroweak baryogenesis (EWBG) [8][9][10][11][12][13][14][15], models for spontaneous (or coherent) baryogenesis [6,16], and for variants of leptogenesis [17][18][19][20]. In this paper we extend our formalism to the case of flavour mixing.…”

“…These equations may have nonzero solutions only if the determinant of (B h ) ij vanishes. This 4 × 4-determinant is easily evaluated for each flavour element ij, giving rise to N 2 independent constraints: 20) where ω i ≡ (k 2 + m 2 i ) 1/2 . These conditions give rise to a singular shell structure: g hα ∼ δ(k 0 ∓ω ij ) or g hα ∼ δ(k 0 ∓ ∆ω ij ).…”

Backreaction effects on nonequilibrium spectral function

“…In this paper we will focus on a simple scalar model following the definitions of [27] with an interaction of the form L ∼ gφχ 2 , where the field φ is the weakly coupled out-ofequilibrium field and χ is a strongly coupled field that composes the thermal bath, which can also be coupled to other fields in equilibrium. As in [7] and [27], the mass of the φ field is much larger than the mass of the particles in the bath, i.e. m φ m χ .…”

“…The KBE are differential-integral equations where the important properties come from the convolution of full propagators with the self-energy. Although the KBE are hard to work with and normally they can only be treated numerically, it was shown in [7] that they can be solved analytically in the leptogenesis scenario. This simple scenario can be used as the starting point to comprehend the properties of the KBE and their relation to the semiclassical Boltzmann equation, where already numerous studies has been performed [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”

“…The study of these effects can be approached in a methodic way using the results obtained in [7] for a weakly coupled field. Results which can be extended for more complicated scenarios.…”