Texture of Yukawa coupling matrices in general two-Higgs-doublet model

Abstract We discuss possible parallel textures of the Yukawa coupling matrices in the general two-Higgsdoublet model (2HDM). In those textures the flavor changing neutral currents are naturally suppressed. Motivated by a phenomenologically successful texture with four texture zeros in the standard model, we propose a predictive ansatz for the Yukawa coupling matrices with the same texture in the general 2HDM. Compared with the six texture-zero based ansatz proposed by Cheng and Sher, it is in a better agreement with the data of quark mixings and CP violation. The four texture-zero based ansatz predicts a different hierarchy in the Yukawa coupling matrix elements. As a consequence, in the lepton sector, the related Yukawa couplings are less constrained by the experimental upper bound of μ → eγ, which allows significantly larger predictions for other processes. The contributions from neutral scalar interactions to the lepton number violation decay modes l → l1l2l3 are calculated in both ansatz. It is shown that the predictions from the four texture-zero based ansatz could be two order of magnitude greater than that from the six texturezero based one. The branching ratio of μ → 3e and τ → 3μ can reach 7.5× 10−17 and 1.3× 10−10 respectively. The predicted ratio of Br(μ → 3e)/Br(τ → 3e) is also larger and almost parameter independent. Those differences make the two ansatz to be easily distinguished by the future experiments.