We study flavor-violating processes in the production or decay of a neutral pseudoscalar meson $P^0$ in the framework of a type-III two Higgs doublet model with four-texture Yukawa couplings. We use a version of the model where Yukawa interactions of neutral Higgs bosons allow for flavor change at the tree-level, but conserve $CP$ symmetry. The physical Yukawa couplings respect $CP$-invariance due to the Hermiticity conditions that we impose on the fermion mass matrices. We focus on all possible ${\tau }^{\pm }\to l^{\pm }{P}^0$ and $P^0\to l^{+}{l}^{\prime -}$ decay channels, where $l$, $l^{\prime }$ are charged leptons. We find that these processes provide complementary information on quark and lepton flavor-changing neutral current Yukawa couplings. In particular flavor-violating parameters in the quark sector, ${\chi }_{sb}$ and ${\chi }_{db}$, are significantly constrained by present experimental data, whereas the corresponding parameters in the leptonic sector are less constrained.

• Received 20 May 2009

DOI:https://doi.org/10.1103/PhysRevD.80.055017