M. Flanz

Baryogenesis from a lepton asymmetric universe

We demonstrate that CP-violation in the Majorana mass matrices of the heavy neutrinos can generate a CP-asymmetric universe. The subsequent decay of the Majorana particles generates a lepton number asymmetry. During the electroweak phase transition the lepton asymmetry is converted into a baryon asymmetry, which survives down to this time.

Baryogenesis through mixing of heavy Majorana neutrinos

Abstract A mechanism is presented in which the mixing of right-handed heavy Majorana neutrinos creates a CP-asymmetric universe. When these Majorana neutrinos subsequently decay more leptons than anti leptons are produced. Due to a resonance phenomenon the lepton asymmetry created by this new mechanism can exceed by a few orders of magnitude any lepton asymmetry originating from direct decays. The asymmetry is finally converted into a baryon asymmetry during the electroweak phase transition.

Further considerations on the CP asymmetry in heavy Majorana neutrino decays

We work out the thermodynamic equations for the decays and scatterings of heavy Majorana neutrinos including the constraints from unitarity. The Boltzmann equations depend on the CP asymmetry parameter which contains both, a self-energy and a vertex correction. At thermal equilibrium there is no net lepton asymmetry due to the CPT theorem and the unitarity constraint. We show explicitly that deviations from thermal equilibrium create the lepton asymmetry.

Bounds on effective Majorana neutrino masses at HERA

Abstract The lepton-number violating process e ± p→ν e ( ν e )l ± l′ ± X mediated by Majorana neutrinos is studied for the HERA collider for (ll′)=(eτ), (μτ), (μμ) and ( ττ ). Only the muonic decay of the τ is considered. The limit on the effective muon Majorana mass, 〈 m μμ 〉 is improved significantly to 4.0·10 3 GeV and for the first time limits on the analogous effective masses connected with the tau sector are given, namely 8.4·10 3 GeV for 〈 m eτ 〉, 8.7·10 3 GeV for 〈 m μτ 〉 and 2.0·10 4 GeV for 〈 m ττ 〉. We find that a more general analysis for an upgraded HERA could improve this values by a factor of up to 40.

Trimuon production in \(\nu\)N-scattering as a probe of massive neutrinos

Abstract. The lepton–number violating process

CP violation in the scattering of heavy bosons and its importance for baryogenesis

{\mbox{

Baryogenesis through CP-violation in the mass matrix [Phys. Lett. B 345 (1995) 248]

\nu_\mu

Leptogenesis with “fuzzy mass shell” for Majorana neutrinos

}}N{\rightarrow} \mu^- \mu^+ \mu^+ X

Erratum to: “Bounds on effective Majorana neutrino masses at HERA”: [Phys. Lett. B 473 (2000) 324–329]1

is studied for the first time in connection with Majorana neutrino masses of the second generation. The sensitivity for light and heavy Majorana neutrinos is investigated. The ratio with respect to the standard model charged current process is improved by some orders of magnitude if compared to previously discussed Majorana induced

Baryogenesis through CP-violation in the mass matrix

\Delta L_{\mu} = 2