München 2009 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 16: Flavorphysik (Theorie) 3
T 16.8: Vortrag
Donnerstag, 12. März 2009, 18:30–18:45, M001
The Cabibbo angle in D14 — •Alexander Blum1 and Claudia Hagedorn2 — 1Max-Planck-Institut für Kernphysik, Heidelberg — 2Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italien
A supersymmetric model with the flavor symmetry D14 is presented, which predicts the value of the CKM matrix element |Vud| and thus the Cabibbo angle θC to be |Vud| =cos( π/14 ) ≈ 0.97493 and sin( θC ) ≈ |Vus| = sin( π/14 ) ≈ 0.2225. D14 is spontaneously broken by flavons, which are scalar gauge singlets. The prediction of |Vud| (θC) is based on the fact that different Z2 subgroups of D14 are conserved in the up and the down quark sector. In order to achieve this D14 is accompanied by a Z3 symmetry. The quark mass hierarchy is partly due to the flavor symmetry D14 and partly due to a Froggatt-Nielsen symmetry U(1)FN under which only the right-handed quarks transform. The model is completely natural in the sense that all hierarchies observed among the quark masses and mixing angles are generated with the help of symmetries. The crucial issue of the vacuum alignment of the flavons is solved (up to a small number of degeneracies). A study of the next-to-leading order corrections shows that results achieved at the lowest order are only slightly perturbed. This fact also allows |Vud| (θC) to be well inside the small experimental error bars.