We consider a variant of seesaw mechanism by introducing extra singlet neutrinos, with which we show how the low scale leptogenesis is realized without imposing the tiny mass splitting between two heavy Majorana neutrinos required in the resonant leptogenesis. Thus, we can avoid the so-called gravitino problem when our scenario is supersymmetrized. We show that an introduction of the new singlet fermion leads to a new contribution which can enhance the lepton asymmetry for certain range of parameter space. We also examine how both the light neutrino mass spectrum and relatively light sterile neutrinos of order a few 100 MeV can be achieved without being in conflict with the constraints on the mixing between the active and sterile neutrinos.
|Number of pages||5|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 2007 Mar 22|
Bibliographical noteFunding Information:
S.K.K. is supported in part by the KOSEF SRC program through CQUeST with Grant No. R11-2005-021 and in part by the KRF Grant funded by the Korean Government (MOEHRD) (KRF-2006-003-C00069). C.S.K. is supported in part by CHEP-SRC and in part by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) No. KRF-2005-070-C00030.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics