CERN Accelerating science

Article
Report number	hep-ph/0401240 ; DESY-03-100 ; DESY-2003-100 ; UAB-FT-551 ; CERN-TH-2003-199
Title	Leptogenesis for Pedestrians
Author(s)	Buchmüller, Wilfried (Deutsches Elektronen Synchrotron DESY, Hamburg) ; Di Bari, P (IFAE, Universitat Autonoma de Barcelona, Bellaterra) ; Plümacher, M (CERN)
Publication	2005
Imprint	30 Jan 2004
Number of pages	55
In:	Ann. Phys. 315 (2005) 305-351
DOI	10.1016/j.aop.2004.02.003
Subject category	Particle Physics - Phenomenology
Abstract	During the process of thermal leptogenesis temperature decreases by about one order of magnitude while the baryon asymmetry is generated. We present an analytical description of this process so that the dependence on the neutrino mass parameters becomes transparent. In the case of maximal CP asymmetry all decay and scattering rates in the plasma are determined by the mass M_1 of the decaying heavy Majorana neutrino, the effective light neutrino mass tilde{m}_1 and the absolute mass scale bar{m} of the light neutrinos. In the mass range suggested by neutrino oscillations, m_{sol} \simeq 8*10^{-3} eV \lesssim \tilde{m}_1 \lesssim m_{atm} \simeq 5*10^{-2} eV, leptogenesis is dominated just by decays and inverse decays. The effect of all other scattering processes lies within the theoretical uncertainty of present calculations. The final baryon asymmetry is dominantly produced at a temperature T_B which can be about one order of magnitude below the heavy neutrino mass M_1. We also derive an analytical expression for the upper bound on the light neutrino masses implied by successful leptogenesis.

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