The two-loop contributions to muon MDM in U(1)_X SSM

Abstract

The MSSM is extended to the U(1)_X SSM, whose local gauge group is SU(3)_C times SU(2)_L times U(1)_Y times U(1)_X. To obtain the U(1)_X SSM, we add the new superfields to the MSSM, namely: three Higgs singlets {hat{eta }},~hat{{bar{eta }}},~{hat{S}} and right-handed neutrinos {hat{nu }}_i. It can give light neutrino tiny mass at the tree level through the seesaw mechanism. The study of the contribution of the two-loop diagrams to the MDM of muon under U(1)_X SSM provides the possibility for us to search for new physics. In the analytical calculation of the loop diagrams (one-loop and two-loop diagrams), the effective Lagrangian method is used to derive muon MDM. Here, the considered two-loop diagrams include Barr-Zee type diagrams and rainbow type two-loop diagrams, especially Z–Z rainbow two-loop diagram is taken into account. The obtained numerical results can reach 7.4times 10^{-10}, which can remedy the deviation between SM prediction and experimental data to some extent.