Lepton flavor-changing Scalar Interactions and Muon g−2g-2

A systematic investigation on muon anomalous magnetic moment and related lepton flavor-violating process such as \m\to e\g, \t\to e\g and \t\to \m\g is made at 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 Barr-Zee diagram. By comparing with the latest data, the allowed ranges for the relevant Yukawa couplings $Y_{ij}$ in lepton sector are obtained. The results show a hierarchical structure of Y_{\m e, \t e} \ll Y_{\m \t} \simeq Y_{\m\m} in the physical basis if $\Delta a_{\mu}$ is found to be $>50\times 10^{-11}$. It deviates from the widely used ansatz in which the off diagonal elements are proportional to the square root of the products of 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 \t\to \m\g is found to be near the current experiment upper bound.Comment: 15 pages, Revtex, 9 figures, published version in EPJ

Internal Energy of the Potts model on the Triangular Lattice with Two- and Three-body Interactions

We calculate the internal energy of the Potts model on the triangular lattice with two- and three-body interactions at the transition point satisfying certain conditions for coupling constants. The method is a duality transformation. Therefore we have to make assumptions on uniqueness of the transition point and that the transition is of second order. These assumptions have been verified to hold by numerical simulations for q=2, 3 and 4, and our results for the internal energy are expected to be exact in these cases.Comment: 9 pages, 4 figure