Calculation for Electric Dipole Moments of Lepton and Neutron in the N-B-LSSM via the Mass Insertion Approximation

Abstract

In the N-B-LSSM, we calculate the electric dipole moments (EDMs) of lepton and neutron at the one loop level via the Mass Insertion Approximation (MIA). In the Standard Model (SM), charge parity (CP) violation originates only from the single phase of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, and the predicted EDMs of lepton and neutron are far below the current experimental upper limits. Thus, EDMs serve as sensitive probes for exploring CP-violating phases in new physics. The N-B-LSSM extends the Minimal Supersymmetric Standard Model (MSSM) by introducing right-handed neutrino superfields and additional singlet Higgs superfields, which enriches the particle spectrum and the sources of CP violation. We derive the one loop analytical expressions for lepton and quark EDMs, and reveal their dependence on model parameters such as $g_{YB}$, $θ_{μ_H}$, $θ_{1'}$, $θ_{BB'}$ and $\tanβ$. Numerical analyses demonstrate that within a reasonable parameter space, the EDMs of leptons (electron, muon, tau) and the neutron can satisfy the current experimental limitations. This study provides a systematic theoretical tool and numerical reference for exploring CP violation and new physics under the N-B-LSSM.

Figures (13)

• Figure 1: Feynman diagrams for generating lepton EDM based on MIA. The external photons are connected to the charged internal lines in all possible ways.
• Figure 2: Feynman diagrams of down-quark for generating neutron EDM based on MIA. External photons connect to charged internal lines in all possible ways, while external gluons connect to colored internal lines.
• Figure 3: Feynman diagrams of up-quark for generating neutron EDM based on MIA. External photons connect to charged internal lines in all possible ways, while external gluons connect to colored internal lines.
• Figure 4: The effects of $g_{YB}$, $\theta_{\mu_H}$ and $\tan\beta$ on $d_{\tau}$.
• Figure 5: The effects of $g_{YB}$, $\theta_{1}$ and $\tan\beta$ on $d_{\mu}$.