LFV decays of Z boson in Minimal R-symmetric Supersymmetric Standard Model

A future Z-factory will offer the possibility of studying rare Z decays Z → l_1l_2, such as those leading to lepton flavor violation(LFV) final states. In this work, by considering the constraints from radiative two-body decays l_2→ l_1γ, we investigate the LFV decays Z → l_1l_2 in the framework of the Minimal R-symmetric Supersymmetric Standard Model with two benchmark points from the existing literature. The flavor-violating off-diagonal entries Б~(12), Б~(13) and Б~(23) are constrained by the current experimental bounds of l_2→ l_1γ. Considering recent experimental constraints, we also investigate Br(Z → l_1l_2) as a function of M_D~W. The numerical results show that the theoretical predictions of Br( Z → l_1l_2) in the MRSSM are several orders of magnitude below the current experimental bounds. The LFV decays Z → eτ and Z →μт may be promising observation targets in future experiments.     

Constraint on the warped space from B→X_sγ

We analyze the theoretical prediction on the branching ratio of B→X_sγ to order Λ_EW²/Λ_KK² in extension of the standard model with a warped extra dimension and the custodial symmetry SU(3)_c×SU(2)_L×SU(2)_R×U(1)_X×P_LR, where Λ_KK denotes the energy scale of low-lying Kaluze-Klein excitations and Λ_EW denotes the electroweak energy scale. Contributions from the in nite series of Kaluze-Klein excitations are summed over through the residue theorem. The numerical result indicates that the present experimental data constrain the parameter space of the concerned model strongly.     

B~0-B~0 Mixing in Local Gauged Baryon and Lepton Numbers

Using the effective Hamiltonian method, we analyze the B0-B0 mixing in the extension of the standard model （SM） where baryon number and lepton number are local gauge symmetries. The numerical results indicate the correction from the extra particles to the mass difference ArnB is significant. There is a 60% enhancement compared to the SM prediction for AraB at most, which agrees with the current experimental result.     

Testing lepton flavor universality in terms of BESⅢ and charm-tau factory data

The recent measurements on R_K and R_π imply that there exists a possible violation of the leptonic flavor universality which is one of the cornerstones of the Standard Model. It is suggested that a mixing between sterile and active neutrinos might induce such a violation. In this work we consider the scenarios with one or two sterile neutrinos to explicitly realize the data while the constraints from the available experiments have been taken into account. Moreover, as indicated in literature, the deviation of the real PMNS matrix from the symmetric patterns may be due to a μ-τ asymmetry, therefore the measurements on R_D(Ds)eμ=Γ(D(D_s)→ e⁺ν_e)/Γ(D(D_s)→ μ⁺ν_μ) and R_D(Ds)μτ=Γ(D(D_s)→ μ⁺ν_μ)/Γ(D(D_s)→ τ⁺ν_τ) (and for some other heavy mesons B^± and B_c etc.) may shed more light on the physics responsible for the violation of the leptonic flavor universality. The data of BESⅢ are available to test the universality and that of future charm-tau factories will provide more accurate information. In this work, we will discuss R_D(Ds)eμ and R_D(Ds)μτ in detail and also briefly consider the cases for B^± and B_c.