CERN Accelerating science

Article
Report number	hep-ph/0302092 ; DESY-03-001 ; UAB-FT-540 ; CERN-TH-2003-016 ; CERN-TH-2003-016 ; DESY-03-001 ; DESY-2003-001 ; UAB-FT-540
Title	The Neutrino Mass Window for Baryogenesis
Author(s)	Buchmuller, W. (DESY) ; Di Bari, P. (Barcelona, IFAE) ; Plumacher, M. (CERN)
Publication	2003
Imprint	12 Feb 2003
Number of pages	29
Note	29 pages, 12 figures included
In:	Nucl. Phys. B 665 (2003) 445-468
DOI	10.1016/S0550-3213(03)00449-8
Subject category	Particle Physics - Phenomenology
Abstract	Interactions of heavy Majorana neutrinos in the thermal phase of the early universe may be the origin of the cosmological matter-antimatter asymmetry. This mechanism of baryogenesis implies stringent constraints on light and heavy Majorana neutrino masses. We derive an improved upper bound on the CP asymmetry in heavy neutrino decays which, together with the kinetic equations, yields an upper bound on all light neutrino masses of 0.1 eV. Lepton number changing processes at temperatures above the temperature T_B of baryogenesis can erase other, pre-existing contributions to the baryon asymmetry. We find that these washout processes become very efficient if the effective neutrino mass \tilde{m}_1 is larger than m_* \simeq 10^{-3} eV. All memory of the initial conditions is then erased. Hence, for neutrino masses in the range from (\Delta m^2_sol)^{1/2} \simeq 8*10^{-3} eV to (\Delta m^2_atm)^{1/2} \simeq 5*10^{-2} eV, which is suggested by neutrino oscillations, leptogenesis emerges as the unique source of the cosmological matter-antimatter asymmetry.
Copyright/License	Elsevier B.V.

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