Is the Unitarity Triangle Right?

Abstract

The latest fits to the CKM matrix indicate that alpha=(90.7+4.5-2.9) degrees. The proximity of alpha to a right-angle raises the question: is it merely accidental or is it due to some physics beyond the Standard Model? In the framework of our recently-proposed flavour permutation symmetry, we consider the similarities between the quark and lepton mixing matrices, V and U, arguing that the relative smallness of one element in each suggests common constraints. These constraints link the smallness of V_ub and U_e3 with each other, and with the approximate mu-tau symmetry observed in leptonic mixing, together with a prediction of a large Dirac CP phase in both the quark and lepton sectors. In the quark case, we predict alpha=(89.0\pm 0.2) degrees, in agreement with data and suggesting that the unitarity triangle is in fact very nearly, but not exactly right.

Talk given at the International Conference on Particles And Nuclei (PANIC08), Eilat, Israel, 13th November 2008. 4 pages

References in corpus (2)

• The Matrix of Unitarity Triangle Angles for Quarks
• Plaquette Invariants and the Flavour Symmetric Description of Quark and Neutrino Mixings

Cited by in corpus (5)

• Right unitarity triangles and tri-bimaximal mixing from discrete symmetries and unification
• Right Unitarity Triangles, Stable CP-violating Phases and Approximate Quark-Lepton Complementarity
• The Matrix of Unitarity Triangle Angles for Quarks
• A Flavour-Symmetric Perspective on Neutrino Mixing
• Nearly right unitarity triangle and CP phase in quark and lepton flavor mixings