Zhou, S (reprint author), Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.
We propose a particularly economical neutrino mass model, in which there are only two right-handed Majorana neutrinos of O(l) TeV and their masses are highly degenerate. Its novel Yukawa-coupling texture together with the seesaw mechanism allows us to achieve the normal neutrino mass hierarchy with m(1) = 0 and a nearly tri-bimaiimal neutrino mixing pattern with the maximal CP-violating phase: theta(23) = pi/4, \delta\ = pi/2 and sin(2) theta(12) = (1 - 2tan(2) theta(13))/3. One may also obtain the inverted neutrino mass hierarchy with m(3) = 0 and the corresponding neutrino mixing pattern with theta(23) = pi/4 and theta(13) = delta = 0. In both cases, it is possible to interpret the cosmological baryon number asymmetry eta(B) approximate to 6.1 x 10(-10) through the resonant leptogenesis mechanism. We demonstrate the significance of flavor-dependent effects in this leptogenesis scenario: they can either flip the sign of the flavor-independent prediction for eta(B) in the m(1) = 0 case or magnify the magnitude of the flavor-independent prediction for eta(B) about 50 times in the m(3) = 0 case. (C) 2007 Elsevier BN. All rights reserved.