Lepton flavor-changing scalar interactions and <Emphasis Type="Italic">g</Emphasis>-2 of the muon

A systematic investigation on the muon's anomalous magnetic moment and a related lepton flavor-violating process such as , and is made at the two-loop level in the models with flavor-changing scalar interactions. The two-loop diagrams with double scalar exchanges are studied and their contributions are found to be compatible with the ones from the Barr-Zee diagram. By comparing with the latest data, the allowed ranges for the relevant Yukawa couplings Y_ij in the lepton sector are obtained. The results show the hierarchical structure in the physical basis if is found to be . It deviates from the widely used ansatz in which the off-diagonal elements are proportional to the square root of the products of the related fermion masses. An alternative Yukawa coupling matrix in the lepton sector is suggested to understand the current data. With such a reasonable Yukawa coupling ansatz, the decay rate of is found to be near the current experiment upper bound. Received: 5 September 2002 / Revised version: 11 January 2003 / Published online: 26 February 2003 RID="a" ID="a" e-mail: zhou@theorie.physik.uni-muenchen.de RID="b" ID="b" e-mail: ylwu@itp.ac.cn