arXiv subjects

Sheng-Kai Cui

Publications and source records attributed to Sheng-Kai Cui.

8 recordsLinked to original sources

arXiv2025

$S, T, U$ Parameters in The B-LSSM

Using the pinch technique, we compute the one-loop vertices of weak interactions in the B-LSSM and incorporate their pinch contributions into the gauge boson self-energies. Compared to the definitions of the $S, T,$ and $U$ parameters in the Standard Model based on the $SU(2)_L \otimes U(1)_Y$ group, the corresponding parameters in the local B-L gauge symmetry (B-LSSM) are modified. We provide these redefined $S, T,$ and $U$ parameters and demonstrate the convergence of the results. In the framework of the low-energy effective Lagrangian for weak interactions, the $S, T,$ and $U$ parameters can be expressed as functions of certain parameters in the B-LSSM. The updated experimental and fitting results constrain the parameter space of the B-LSSM strongly.

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arXiv2024

Lepton-flavor violation in the left-right supersymmetric standard model

In the Standard Model (SM), the charged lepton-flavor violation (CLFV) processes are forbidden, so the observation of CLFV represents a clear signal of new physics that goes beyond the Standard Model. In this work, we focus on the CLFV processes $l_{j}^{-}\to l_{i}^{-}γ$ and $l_{j}^{-}\to l_{i}^{-}l_{i}^{-}l_{i}^{+}$ in LRSSM. Considering the constraints of the updated experimental datas, the numerical results show that the new contributions of $SU{{\left( 2 \right)}_{R}}$ gauge interaction and a large number of other new particles, such as ${{Z}^{'}}$ boson, double-charged Higgs-bosons in LRSSM can make significant contributions to the CLFV processes $l_{j}^{-}\to l_{i}^{-}γ$ and $l_{j}^{-}\to l_{i}^{-}l_{i}^{-}l_{i}^{+}$, which is much different from the ones predicted in other SUSY models. This work provide a theoretical base for finding the LFV phenomena in new physics.

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arXiv2024

W boson mass in the NP models with extra $U(1)$ gauge group

The precise measurement of the W boson mass is closely related to the contributions of new physics (NP), which can significantly constrain the parameter space of NP models, particularly those with an additional $U(1)$ local gauge group. The inclusion of a new $Z'$ gauge boson and gauge couplings in these models can contribute to the oblique parameters $S$, $T$, $U$ and W boson mass at tree level. Taking into account the effects of kinetic mixing, we calculate and analyze the oblique parameters $S$, $T$, $U$ and W boson mass in such NP models in this study. It is found that the kinetic mixing effects can make significant contributions to the W boson mass, which can satisfy the recently measured W boson mass at CDF II or ATLAS by choosing appropriate values of gauge coupling constants and extra $U(1)$ group charges of leptons or scalar doublets. In addition, if the leptonic Yukawa couplings are invariant under the extra $U(1)$ local gauge group, these contributions can be eliminated by redefining the gauge boson fields through eliminating the neutral currents involving charged leptons, even with nonzero kinetic mixing effects.

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arXiv2023

B meson rare decays in the TNMSSM

We investigate the two loop electroweak corrections to B meson rare decays $\bar B\rightarrow X_sγ$ and $B_s^0\rightarrow μ^+μ^-$ in the minimal supersymmetry standard model (MSSM) extension with two triplets and one singlet (TNMSSM). The new particle contents and interactions in the TNMSSM can affect the theoretical predictions of the branching ratios ${\rm Br}(\bar B\rightarrow X_sγ)$ and ${\rm Br}(B_s^0\rightarrow μ^+μ^-)$, and the corrections from two loop diagrams to the process $\bar B\rightarrow X_sγ$ can reach around $4\%$. Considering the latest experimental measurements, the numerical results of ${\rm Br}(\bar B\rightarrow X_sγ)$ and ${\rm Br}(B_s^0\rightarrow μ^+μ^-)$ in the TNMSSM are presented and analyzed. It is found that the results in the TNMSSM can fit the updated experimental data well and the new parameters $T_λ,\;κ,\;λ$ affect the theoretical predictions of ${\rm Br}(\bar B\rightarrow X_sγ)$ and ${\rm Br}(B_s^0\rightarrow μ^+μ^-)$ obviously.

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arXiv2020

Muon conversion to electron in nuclei in Minimal R-symmetric Supersymmetric Standard Model

We analyze the lepton flavor violating process $μ-e$ conversion in the framework of the minimal R-symmetric supersymmetric standard model. The theoretical predictions are determined by considering the experimental constraint on parameter $δ^{12}$ from the lepton flavor violating decay $μ\rightarrow e γ$. The numerical results show that $γ$ penguins and Z penguins dominate the predictions on CR($μ-e$,Nucleus), and the contributions from Higgs penguins and box diagrams are insignificant. The theoretical predictions on conversion rate CR($μ-e$,Nucleus) in a Al or Ti target can be enhanced close to the future experimental sensitivities and are very promising to be observed in near future experiment.

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arXiv2020

Electric dipole moments of neutron and heavy quarks in the B-L symmetric MSSM

The searching for the electric dipole moments (EDMs) of neutron ($d_n$), $b$ quark ($d_b$) and $c$ quark ($d_c$) gives strict upper bounds on these quantities. And recently, new upper bounds on $d_b$, $d_c$ are obtained by the strict limit on $d_n$. The models of new physics (NP) with additional CP-violating (CPV) sources are constrained strictly by these EDMs. In this work, we focus on the CPV effects on these EDMs in the minimal supersymmetric extension (MSSM) of the SM with local $B-L$ gauge symmetry (B-LSSM). The contributions from one-loop and some two-loop diagrams to the quark EDM are given in general form, which can also be used in the calculation of quark EDM in other models of NP. Considering the constrains from updated experimental data, the numerical results show that the two-loop corrections can make important contributions to these EDMs. Compared with the MSSM, the effects of new CPV phases and new parameters in the B-LSSM on these EDMs are also explored.

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arXiv2019

$l_α\rightarrow 3l_β$ in Minimal R-symmetric Supersymmetric Standard Model

Lepton flavor violation decays are channels which may lead to fundamental discoveries in the forthcoming years and this make it an exciting research field for beyond the Standard Model searches. In this work, we present an analysis of the lepton flavor violation decays $l_α\rightarrow 3l_β$ in Minimal R-symmetric Supersymmetric Standard Model. The prediction for BR($l_α\rightarrow 3l_β$) depend on the off-diagonal entries of the slepton mass matrix. The contributions to Wilson coefficients can be classified into Higgs penguins, photon penguins, Z penguins, and box diagrams. It shows the contribution from Z penguins dominates the predictions for BR($l_α\rightarrow 3l_β$), and the contributions from Higgs penguins and box diagrams play different roles in different decay channels. The theoretical predictions for BR($l_α\rightarrow 3l_β$) can reach the future experimental limits, and there channels are very promising to be observed in near future experiment.

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arXiv2019

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

A future $Z$-factory will offer the possibility to study rare $Z$ decays $Z\rightarrow l_1l_2$, as those leading to Lepton Flavor Violation final states. In this work, by taking account of the constraints from radiative two body decays $l_2\rightarrow l_1γ$, we investigate the Lepton Flavor Violation decays $Z\rightarrow l_1l_2$ in the framework of Minimal R-symmetric Supersymmetric Standard Model with two benchmark points from already existing literatures. The flavor violating off-diagonal entries $δ^{12}$, $δ^{13}$ and $δ^{23}$ are constrained by the current experimental bounds of $l_2\rightarrow l_1γ$. Considering recent experimental constraints, we also investigate Br($Z\rightarrow l_1l_2$) as a function of $M_D^W$. The numerical results show that the theoretical prediction of Br($Z\rightarrow l_1l_2$) in MRSSM are several orders of magnitude below the current experimental bounds. The Lepton Flavor Violation decays $Z\rightarrow eτ$ and $Z\rightarrow μτ$ may be promising to be observed in future experiment.

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