Göttingen 2012 – scientific programme

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T: Fachverband Teilchenphysik

T 21: Astroteilchenphysik, Kosmologie / Neutrinophysik (Theorie)

T 21.4: Talk

Tuesday, February 28, 2012, 17:30–17:45, VG 3.101

Nonequilibrium approach to |Δ L|=2 scattering processes in leptogenesis — •Tibor Frossard¹, Mathias Garny², Andreas Hohenegger³, Alexander Kartavtsev¹, and David Mitrouskas¹ — ¹Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany — ²Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — ³Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

In the baryogenesis-via-leptogenesis scenario the lepton asymmetry produced by the decay of the heavy Majorana neutrinos is partially washed out by the inverse decay and Δ L=2 scattering processes. In the canonical approach amplitudes of these processes are computed in vacuum and used in the Boltzmann equation which describes the time evolution of the asymmetry. The resulting equation suffers from the so-called double-counting problem and neglects the medium effects. A consistent description of the asymmetry generation in the early Universe can be achieved using methods of nonequilibrium QFT. Starting from first principles we derive a Boltzmann-like equation for the lepton number which includes the decay, inverse decay and Δ L=2 scattering processes. The obtained equation takes into account the medium effects, incorporates quantum statistical factors and is free of the double-counting problem.