Theory Seminar

KEK 素粒子原子核研究所・理論セミナー

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TITLE：	None-zero-Ue3 and leptogenesis through spontaneous A4 symmetry breaking
	（英語/in English)
SPEAKER：	Dr. Yang-Hwan Ahn
DATE：	January 29 (Fri.) 14:00-
PLACE:	KEK Bidg.4, 3F Room 345

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　　　 （ABSTRACT）

If A4 flavour symmetry is considered, it seems to be extremely attractive because of their predictions of tri-bimaximal mixing (U_{e3}=0, U_{e2}=1/sqrt{2},U_{mu3}=1/sqrt {2}) and naturalness. The recent analysis based on global fits of the available data gives us hints for theta_{13}>0 at 1 sigma, a relatively large Ue3, even which is not yet a significant indication for a non-zero theta_{13}. In addition to this, even higher order terms are considered, at a very large scale (around 10^{13}-10^{14} GeV) the BAU is successfully explained, A4 symmetry (with hierarchical heavy Majorana neutrino mass pattern) itself could not explain the Baryon asymmetry of the Universe in a Lagrangian level. We address the possibility of a link between TeV-leptogenesis and a relatively large Ue3 through spontaneous symmetry breaking of A4 in a radiative seesaw mechanism.