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Abstract

A Systematic Approach to Leptogenesis in the Standard Model. The mechanism of Leptogenesis realized in the SM+3v_R offers a convincing explanation for the observed matter to anti-matter asymmetry of the universe. Although it is a genuine quantum effect, its statistical aspects have been commonly treated in terms of cJassical equations. This ambiguous interplay of particle physics and cosmology is critically reviewed leading to the conclusion that in this conventional approach quantum statistical properties cannot be included without violating the third Sakharov condition. A first principle approach based on the CTP Kadanoff-Baym formalism of nonequilibrium QFT is required. A comprehensive introduction to the necessary concepts is followed by an application to Leptogenesis in the case of a hierarchical mass spectrum. We derive effective in-medium amplitudes of the relevant processes and obtain quantum kinetic equations. They include both, CP-violating decay and Δ,L = 2 lepton number violating scattering processes but are not affected by the usually encountered double counting problem. In other words, quantum statistical effects need not be neglected anymore. In addition, thermal corrections to the CP-violating parameter arise. In agreement with previous findings, the structure of the thermal corrections differs from earlier results obtained in the framework of thermal QFT.