Right Unitarity Triangles, Stable CP-violating Phases and Approximate Quark-Lepton Complementarity

Current experimental data indicate that two unitarity triangles of the CKM quark mixing matrix V are almost the right triangles with α ≈ 90. We highlight a very suggestive parametrization of V and show that its CP-violating phase φ is nearly equal to α (i.e., φ − α ≈ 1.1). Both φ and α are stable against the renormalizaton-group evolution from the electroweak scale MZ to a superhigh energy scale MX or vice versa, and thus it is impossible to obtain α = 90 at MZ from φ = 90 ◦ at MX . We conjecture that there might also exist a maximal CP-violating phase φ ≈ 90 in the MNS lepton mixing matrix U . The approximate quark-lepton complementarity relations, which hold in the standard parametrizations of V and U , can also hold in our particular parametrizations of V and U simply due to the smallness of |Vub| and |Ve3|. PACS number(s): 12.15.Ff, 12.38.Bx, 12.10.Kt, 13.10.+q, 14.60.Pq, 25.30.Pt