  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.
