arXiv subjects

Long Ruan

Publications and source records attributed to Long Ruan.

3 recordsLinked to original sources

arXiv2024

Neutrino transition magnetic moment in the $U(1)_X$SSM

This paper investigates the neutrino transition magnetic moment in the $U(1)_X$SSM. $U(1)_X$SSM is the $U(1)$ extension of Minimal Supersymmetric Standard Model (MSSM) and its local gauge group is extended to $SU(3)_C\times SU(2)_L \times U(1)_Y\times U(1)_X$. To obtain this model, three singlet new Higgs superfields and right-handed neutrinos are added to the MSSM, which can explain the results of neutrino oscillation experiments. The neutrino transition magnetic moment is induced by electroweak radiative corrections. By applying effective Lagrangian method and on-shell scheme, we study the associated Feynman diagrams and the transition magnetic moment of neutrinos in the model. We fit experimental data for neutrino mass variances and mixing angle. Based on the range of data selection, the influences of different sensitive parameters on the results are analysed. The numerical analysis shows that many parameters have an effect on the neutrino transition moment, such as $g_X$, $M_2$, $\lambda_H$ and $g_{YX}$. For our numerical results, the order of magnitude of $\mu_{ij}^M/\mu_B$ is around $10^{-20}$ $\sim$ $10^{-19}$.

hep-ph↗

arXiv2024

Study some two loop contribution to muon anomalous MDM in the N-B-LSSM

It is well known that the muon magnetic dipole moment (MDM) has close relation with the new physics (NP) in the development of the Standard Model (SM). Combined with the Fermilab National Accelerator Laboratory (FNAL) and the Brookhaven National Laboratory (BNL) E821 result, the departure from the SM prediction is about 5.0 $\sigma$. We study the electroweak corrections from several type two-loop SUSY diagrams and the virtual SUSY particles include chargino, neutralino, scalar lepton and scalar neutrino. Based on the latest experimental constraints, we study the {muon anomalous MDM} under the next to the minimal supersymmetric extension of the SM with local B-L gauge symmetry (N-B-LSSM). The abundant numerical results verify that $\tan{\beta},~T_e,~M^2_L,~M^2_e,~M_{BB'}$ play an important role in {muon anomalous MDM}. $M^2_e,~\tan{\beta}$ and $T_e$ are sensitive parameters to {muon anomalous MDM}. From the data obtained in all the figures of the numerical results, most of the values of $a_{\mu}^{NBL}$ are in 2$\sigma$ interval, which can compensate the departure between the experiment data and the SM prediction.

hep-ph↗

arXiv2024

Right-handed neutrino dark matter in $U(1)_X$SSM

There is strong evidence for the existence of dark matter in a number of current experiments. We study dark matter using the $U(1)_X$SSM obtained from the $U(1)_X$ extension of the minimal supersymmetric standard model (MSSM). In the $U(1)_X$SSM, we use the right-handed neutrino as a dark matter candidate, whose lightest mass eigenstate has cold dark matter features. In this paper, the relic density of right-handed neutrino as dark matter is investigated. For dark matter scattering, both spin-independent and spin-dependent cross sections are studied. In the final numerical results obtained, some parameter spaces can satisfy the constraints of the relic density and dark matter direct detection experiments.

hep-ph↗