arXiv subjects

Guo-Zhu Ning

Publications and source records attributed to Guo-Zhu Ning.

17 recordsLinked to original sources

arXiv2026

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

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 EDM measurements strongly constrain the CP-violating parameter space of the N-B-LSSM and reveal the sensitivity of lepton and neutron EDMs to the extended gauge interactions and supersymmetric parameters. This study provides a systematic theoretical tool and numerical reference for exploring CP violation and new physics under the N-B-LSSM.

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arXiv2026

Lepton flavor violating decays $l_j \rightarrow l_iγ$ in the $U(1)_X$VLFM

In the $U(1)_X$ vector-like fermion model ($U(1)_X$VLFM), the Standard Model(SM) gauge group is extended with an additional $U(1)_X$ symmetry. Vector-like fermions and right-handed neutrinos are introduced, providing new sources of lepton flavor violation(LFV). In this paper, we perform a detailed study of the LFV decays $l_j \to l_i γ$ (with $j = τ, μ$; $i = μ, e$; $i \neq j$) in this model. The numerical results show that, in certain parameter regions, the branching ratios of these processes can become large enough to be probed in future experiments. This work provides important theoretical guidance and constraints for exploring new physics beyond the SM.

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arXiv2025

Relativistic effects in the strong and electromagnetic decays of ${D^*}$ meson

In this paper, we solve the complete Salpeter equation and use the obtained relativistic wave function to calculate the strong and radiative electromagnetic decays of the ${D^*}$ meson. { We obtain the results $Γ(D^{*}(2007)^{0}\to D^{0}π^{0})=34.6~\rm{keV}$ and $Γ(D^{*}(2007)^{0}\rightarrow D^{0}γ)=19.4~\rm{keV}$, and the estimated full width is $Γ(D^{*}(2007)^{0})=54.0~\rm{keV}$.} The focus of this study is on the relativistic corrections. In our method, the wave function of the $D$ meson is not a pure $S$-wave, but includes both a non-relativistic $S$-wave and a relativistic $P$-wave, while the wave function of the $D^*$ meson includes a non-relativistic $S$-wave as well as both relativistic $P$-wave and $D$-wave. Therefore, in this case, the decay ${D^{*}\rightarrow{D}γ}$ is not a non-relativistic $M1$ transition, but rather an $M1+E2+M3+E4$ decay. We find that in a strong decay $D^{*}\rightarrow{D}π$, the non-relativistic contribution is dominant, while in an electromagnetic decay ${D^{*}\rightarrow{D}γ}$, the relativistic correction is dominant.

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arXiv2022

Pair production of neutral Higgs particles in the B-LSSM

Higgs pair production provides a unique handle for measuring the strength of Higgs self interaction and constraining the shape of the Higgs potential. Including radiative corrections to the trilinear couplings of $CP$-even Higgs, we investigate the cross section of the lightest neutral Higgs pair production in gluon fusion at the Large Hadron Collider in the supersymmetric extensions of the standard model. Numerical results indicate that the correction to the cross section is about 11\% in the B-LSSM, while is only about 4\% in the MSSM. Considering the constraints of the experimental data of the lightest Higgs, we find that the gauge couplings of $U(1)_{B-L}$ and the ratio of the nonzero vacuum expectation values of two singlets also affect strongly the theoretical evaluations on the production cross section in the B-LSSM.

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arXiv2021

Light neutralino dark matter in $U(1)_X$SSM

The $U(1)_X$ extension of the minimal supersymmetric standard model(MSSM) is called as $U(1)_X$SSM with the local gauge group $SU(3)_C\times SU(2)_L \times U(1)_Y \times U(1)_X$. $U(1)_X$SSM has three singlet Higgs superfields beyond MSSM. In $U(1)_X$SSM, the mass matrix of neutralino is $8\times8$, whose lightest mass eigenstate possesses cold dark matter characteristic. Supposing the lightest neutralino as dark matter candidate, we study the relic density. For dark matter scattering off nucleus, the cross sections including spin-independent and spin-dependent are both researched. In our numerical results, some parameter space can satisfy the constraints from the relic density and the experiments of dark matter direct detection.

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arXiv2020

$e^{+}e^-\rightarrow hhZ$ in the B-L symmetric SSM

The double Higgs boson production through $e^{+}e^-\rightarrow hhZ$ is analyzed in the minimal supersymmetric extension of the Standard Model(SM) with the local gauge symmetry $U(1)_{B-L}$, where $h$ denotes the lightest Higgs boson with 125 GeV. Considering the constraints from the updated prediction data, we find that the production cross section of this process in the model depends on some parameters strongly.

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arXiv2019

Scalar neutrino dark matter in $U(1)_X$SSM

$U(1)_X$SSM is the extension of the minimal supersymmetric standard model(MSSM) and its local gauge group is $SU(3)_C\times SU(2)_L \times U(1)_Y \times U(1)_X$. To obtain this model, three singlet new Higgs superfields and right-handed neutrinos are added to MSSM. In the framework of $U(1)_X$SSM, we study the Higgs mass and take the lightest CP-even sneutrino as a cold dark matter candidate. For the lightest CP-even sneutrino, the relic density and the cross section for dark matter scattering off nucleon are both researched. In suitable parameter space of the model, the numerical results satisfy the constraints of the relic density and the cross section with the nucleon.

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arXiv2018

Top quark decays with flavor violation in the B-LSSM

The decays of top quark $t\rightarrow cγ,\;t\rightarrow cg,\;t\rightarrow cZ,\;t\rightarrow ch$ are extremely rare processes in the standard model (SM). The predictions on the corresponding branching ratios in the SM are too small to be detected in the future, hence any measurable signal for the processes at the LHC is a smoking gun for new physics. In the extension of minimal supersymmetric standard model with an additional local $U(1)_{B-L}$ gauge symmetry (B-LSSM), new gauge interaction and new flavor changing interaction affect the theoretical evaluations on corresponding branching ratios of those processes. In this work, we analyze those processes in the B-LSSM, under a minimal flavor violating assumption for the soft breaking terms. Considering the constraints from updated experimental data, the numerical results imply $Br(t\rightarrow cγ)\sim5\times10^{-7}$, $Br(t\rightarrow cg)\sim2\times10^{-6}$, $Br(t\rightarrow cZ)\sim4\times10^{-7}$ and $Br(t\rightarrow ch)\sim3\times10^{-9}$ in our chosen parameter space. Simultaneously, new gauge coupling constants $g_{_B},\;g_{_{YB}}$ in the B-LSSM can also affect the numerical results of $Br(t\rightarrow cγ,\;cg,\;cZ,\;ch)$.

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arXiv2018

Higgs boson decay $h^0\rightarrow m_VZ$ in the BLMSSM

In the framework of BLMSSM, the Higgs decays $h^0\rightarrow Zγ$ and $h^0\rightarrow m_VZ$ are studied where $m_V$ represents a vector meson($ρ, ω, ϕ, J/ψ, Υ$ etc.). Corrections to the CP-even and CP-odd $h^0γZ$ couplings occur via loop diagrams where new particles are involved. Actually both of them obviously influence the decay rates of $h^0\rightarrow Zγ$ and $h^0\rightarrow m_VZ$. Concretely, our obtained numerical result shows that the decay width of $h^0\rightarrow Zγ$ can be 1.3 times larger than the prediction of the Standard Model(SM). For the light mesons ($ρ,ω$), the corrections to $h^0\rightarrow m_VZ$ are within $15\%\sim 20\%$ still consistent with the SM results. The results of this work would encourage a detection on $h^0\rightarrow Zγ$ at LHC for exploring new physics beyond SM.

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arXiv2018

The extended BLMSSM with a 125 GeV Higgs boson and dark matter

To extend the BLMSSM, we not only add exotic Higgs superfields $(Φ_{NL},φ_{NL})$ to make the exotic lepton heavy, but also introduce the superfields($Y$,$Y^\prime$) having couplings with lepton and exotic lepton at tree level. The obtained model is called as EBLMSSM, which has difference from BLMSSM especially for the exotic slepton(lepton) and exotic sneutrino(neutrino). We deduce the mass matrices and the needed couplings in this model. To confine the parameter space, the Higgs boson mass $m_{h^0}$ and the processes $h^0\rightarrow γγ$, $h^0\rightarrow VV, V=(Z,W)$ are studied in the EBLMSSM. With the assumed parameter space, we obtain reasonable numerical results according to data on Higgs from ATLAS and CMS. As a cold dark mater candidate, the relic density for the lightest mass eigenstate of $Y$ and $Y'$ mixing is also studied.

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arXiv2017

Search for charged lepton flavor violation of vector mesons in BLMSSM model

We analyze the charged lepton flavor violating (CLFV) decays of vector mesons $V\rightarrow l_i^{\pm}l_j^{\mp}$ with $V\in\{ϕ, J/Ψ, Υ, ρ^0, ω\}$ in BLMSSM model. This new model is introduced as an supersymmetric extension of Standard Model (SM), where local gauged baryon number B and lepton number L are considered. The numerical results indicate BLMSSM model can produce significant contributions to such two-body CLFV decays. And the branching ratios for these CLFV processes can easily reach the present experimental upper bounds. Therefore, searching for CLFV processes of vector mesons may be an effective channels to study new physics.

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arXiv2017

Higgs boson mass corrections in the $μν$SSM with effective potential methods

To solve the $μ$ problem of the MSSM, the $μ$ from $ν$ Supersymmetric Standard Model ($μν$SSM) introduces three singlet right-handed neutrino superfields $\hatν_i^c$, which lead to the mixing of the neutral components of the Higgs doublets with the sneutrinos, producing a relatively large CP-even neutral scalar mass matrix. In this work, we analytically diagonalize the CP-even neutral scalar mass matrix and analyze in detail how the mixing impacts the lightest Higgs boson mass. We also give an approximate expression for the lightest Higgs boson mass. Simultaneously, we consider the radiative corrections to the Higgs boson masses with effective potential methods.

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arXiv2016

The one loop corrections to the neutrino masses in BLMSSM

The neutrino masses and mixings are studied in the model which is the supersymmetric extension of the standard model with local gauged baryon and lepton numbers(BLMSSM). At tree level the neutrinos can obtain tiny masses through the See-Saw mechanism in the BLMSSM. The one-loop corrections to the neutrino masses and mixings are important, and they are studied in this work with the mass insertion approximation. We study the numerical results and discuss the allowed parameter space of BLMSSM. It can contribute to study the neutrino masses and to explore the new physics beyond the standard model(SM).

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arXiv2015

Light Doubly Charged Higgs Boson via the $WW^*$ Channel at LHC

The doubly charged Higgs bosons $H^{\pm\pm}$ searches at the Large Hadron Collider (LHC) have been studied extensively and strong bound is available for $H^{\pm\pm}$ dominantly decaying into a pair of same-sign di-leptons. In this paper we point out that there is a large cavity in the light $H^{\pm\pm}$ mass region left unexcluded. In particular, $H^{\pm\pm}$ can dominantly decay into $WW$ or $WW^*$ (For instance, in the type-II seesaw mechanism the triplet acquires a vacuum expectation value around 1 GeV.), and then it is found that $H^{\pm\pm}$ with mass even below $2m_W$ remains untouched by the current collider searches. Searching for such a $H^{\pm\pm}$ at the LHC is the topic of this paper. We perform detailed signal and background simulation, especially including the non-prompt $t\bar{t}$ background which is the dominant one nevertheless ignored before. We show that such $H^{\pm\pm}$ should be observable at the 14 TeV LHC with 10-30 fb$^{-1}$ integrated luminosity.

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arXiv2013

Highlights of Supersymmetric Hypercharge $\pm1$ Triplets

The discovery of a standard model (SM)-like Higgs boson with a relatively heavy mass $m_h$ and hints of di-photon excess has deep implication to supersymmetric standard models (SSMs). We consider the SSM extended with hypercharge $\pm1$ triplets, and investigate two scenarios of it: (A) Triplets significantly couple to the Higgs doublets, which can substantially raise $m_h$ and simultaneously enhance the Higgs to di-photon rate via light chargino loops; (B) Oppositely, these couplings are quite weak and thus $m_h$ can not be raised. But the doubly-charged Higgs bosons, owing to the gauge group structure, naturally interprets why there is an excess rather than a deficient of Higgs to di-photon rate. Additionally, the pseudo Dirac triplet fermion is an inelastic non-thermal dark matter candidate. Light doubly-charged particles, especially the doubly-charged Higgs boson around 100 GeV in scenario B, are predicted. We give a preliminary discussion on their search at the LHC.

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arXiv2010

Flavor Violating Transitions of Charged Leptons from a Seesaw Mechanism of Dimension Seven

A mechanism has been suggested recently to generate the neutrino mass out of a dimension-seven operator. This is expected to relieve the tension between the occurrence of a tiny neutrino mass and the observability of other physics effects beyond it. Such a mechanism would inevitably entail lepton flavor violating effects. We study in this work the radiative and purely leptonic transitions of the light charged leptons. In so doing we make a systematic analysis of the flavor structure by providing a convenient parametrization of the mass matrices in terms of independent physical parameters and diagonalizing them explicitly. We illustrate our numerical results by sampling over two CP phases and one Yukawa coupling which are the essential parameters in addition to the heavy lepton mass. We find that with the stringent constraints coming from the muon decays and the muon-electron conversion in nuclei taken into account the decays of the tau lepton are severely suppressed in the majority of parameter space. There exist, however, small regions in which some tau decays can reach a level that is about 2 orders of magnitude below their current bounds.

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arXiv2009

Radiative Neutrino Mass in Type III Seesaw Model

The simplest type III seesaw model as originally proposed introduces one lepton triplet. It thus contains four active neutrinos, two massive and two massless at tree level. We determine the radiative masses that the latter receive first at two loops. The masses are generally so tiny that they are definitely excluded by the oscillation data, if the heavy leptons are not very heavy, say, within the reach of LHC. To accommodate the data on masses, the seesaw scale must be as large as the scale of grand unification. This indicates that the most economical type III model would entail no new physics at low energies beyond the tiny neutrino masses.

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