Probing Leptogenesis

Preprint number: CP3-Origins-2017-53 DNRF90
Authors: E. J. Chun (Korea Institute for Advanced Study), G. Cvetic (Universidad Tecnica Federico Santa Maria), P. S. B. Dev (Washington University), M. Drewes (Universite Catholique de Louvain), C. S. Fong (Universidade de Sao Paulo), B. Garbrecht (Technische Universitaet Muenchen), T. Hambye (Universite Libre de Bruxelles), J. Harz (ILP, Sorbonne Universites), P. Hernandez (IFIC, Universidad de Valencia), C. S. Kim (Yonsei University), E. Molinaro (CP3-Origins & University of Southern Denmark), E. Nardi (INFN, Laboratori Nazionali di Frascati), J. Racker (IATE, Universidad Nacional de Cordoba), N. Rius (IFIC, Universidad de Valencia), and J. Zamora-Saa (Dzhelepov Laboratory of Nuclear Problems)
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The focus of this chapter lies on the possible experimental tests of leptogenesis scenarios. We consider both leptogenesis generated from oscillations, as well as leptogenesis from out-of-equilibrium decays. As the Akhmedov-Rubakov-Smirnov (ARS) mechanism allows for heavy neutrinos in the GeV range, this opens up a plethora of possible experimental tests, e.g. at neutrino oscillation experiments, neutrinoless double beta decay, and direct searches for neutral heavy leptons at future facilities. In contrast, testing leptogenesis from out-of-equilibrium decays is a quite difficult task. We comment on the necessary conditions for having successful leptogenesis at the TeV-scale. We further discuss possible realizations and their model specific testability in extended seesaw models, models with extended gauge sectors, and supersymmetric leptogenesis. Not being able to test high-scale leptogenesis directly, we present a way to falsify such scenarios by focusing on their washout processes. This is discussed specifically for the left-right symmetric model and the observation of a heavy $W_R$, as well as model independently when measuring $Delta L = 2$ washout processes at the LHC or neutrinoless double beta decay.