arXiv subjects

Hai-Bin Zhang

Publications and source records attributed to Hai-Bin Zhang.

At least 55 records · Page 3Linked to original sources

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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arXiv2020

Electroweak baryogenesis and electron EDM in the B-LSSM

Electroweak baryogenesis (EWB) and electric dipole moment (EDM) have close relation with the new physics beyond the standard model (SM), because the SM CP-violating (CPV) interactions are not sufficient to provide the baryon asymmetry of the universe by many orders of magnitude, and the theoretical predictions for the EDM of electron ($d_e$) in the SM are too tiny to be detected in near future. In this work, we explore the CPV effects on EWB and the electron EDM in the minimal supersymmetric extension (MSSM) of the SM with local $B-L$ gauge symmetry (B-LSSM). And the two-step transition via tree-effects in this model is discussed. Including two-loop corrections to $d_e$ and considering the constrains from updated experimental data, the numerical results show that the B-LSSM can account for the observed baryon asymmetry. In addition, when the cancellation between different contributions to $d_e$ takes place, the region favored by EWB can be compatible with the corresponding EDM bound.

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arXiv2020

GKZ-hypergeometric systems for Feynman integrals

Basing on the systems of linear partial differential equations derived from Mellin-Barnes representations and Miller's transformation, we obtain GKZ-hypergeometric systems of one-loop self energy, one-loop triangle, two-loop vacuum, and two-loop sunset diagrams, respectively. The codimension of derived GKZ-hypergeometric system equals the number of independent dimensionless ratios among the external momentum squared and virtual mass squared. Taking GKZ-hypergeometric systems of one-loop self energy, massless one-loop triangle, and two-loop vacuum diagrams as examples, we present in detail how to perform triangulation and how to construct canonical series solutions in the corresponding convergent regions. The series solutions constructed for these hypergeometric systems recover the well known results in literature.

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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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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 two-loop corrections to lepton MDMs and EDMs in the EBLMSSM

Extending BLMSSM with exotic Higgs superfields $(Φ_{NL},φ_{NL})$ and superfields ($Y,Y^\prime$), one obtains the new model called as EBLMSSM, where exotic leptons are heavy and have tree level couplings with SM lepton. In this model, some new parameters with CP-violating phases are considered, so there are new contributions to lepton anomalous magnetic dipole moments (MDMs) and electric dipole moments (EDMs). Therefore, we study the one-loop, two-loop Barr-Zee and two-loop Rainbow type corrections to lepton MDMs and EDMs in the EBLMSSM. Considering the constraints from the lightest CP-even Higgs mass and decays, we calculate the corresponding numerical results. In our used parameter space, the new physics contributions to lepton MDMs are large, which can remedy the deviation between the SM prediction and experimental result well. New introduced CP-violating phases also affect the lepton EDMs in a certain degree.

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arXiv2019

Study of dark matter in the extended BLMSSM

There are strong evidences for existence of dark matter in some experiments at present. However, the question is that we do not have a reasonable explanation for dark matter in the framework of the Standard Model(SM) of particle physics. It is necessary to extend the SM in order to explain the dark matter. According to the current possible existence conditions of dark matter, we choose $χ^0_L$ and $\tilde{Y}$ as candidates for dark matter in the EBLMSSM. We study the dominant annihilation processes in detail, including $\barχ^0_Lχ^0_L(\bar{\tilde{Y}}\tilde{Y})\rightarrow \bar{l}^Il^I$ and $\barχ^0_Lχ^0_L(\bar{\tilde{Y}}\tilde{Y})\rightarrow \barν^Iν^I$. And we calculate their annihilation cross section $σ$ and relic density $Ω_D h^2$. Then we analyze the limitations of dark matter relic density on the parameters of the EBLMSSM.

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arXiv2019

The system of partial differential equations for the $C_{_0}$ function

We present an approach to analyze the scalar integrals of any Feynman diagrams in detail here. This method not only completely recovers some well-known results in the literature, but also produces some brand new results on the $C_{_0}$ function. The approach can be employed to evaluate the coefficient of arbitrary power of $\varepsilon$ in the expansion of a scalar integral, where $D=4-2\varepsilon$ denotes the time-space dimension.

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arXiv2019

Charged lepton flavor violation in extended BLMSSM

Within the extended BLMSSM, the exotic Higgs superfields $(Φ_{NL},φ_{NL})$ are added to make the exotic leptons heavy, and the superfields ($Y$,$Y^\prime$) are also introduced to make exotic leptons unstable. This new model is named as the EBLMSSM. We study some charged lepton flavor violating (CLFV) processes in detail in the EBLMSSM, including $l_j\rightarrow l_i γ$, muon conversion to electron in nuclei, the $τ$ decays and $h^0\rightarrow l_i l_j$. Being different from BLMSSM, some particles are redefined in this new model, such as slepton, sneutrino, exotic lepton (neutrino), exotic slepton (sneutrino) and lepton neutralino. We also introduce the mass matrices of superfields $Y$ and spinor $\tilde{Y}$ in the EBLMSSM. All of these lead to new contributions to the CLFV processes. In the suitable parameter space, we obtain the reasonable numerical results. The results of this work will encourage physicists to explore new physics beyond the SM.

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arXiv2019

One loop correction to $Z\rightarrow νν$ in the Minimal R-symmetric Supersymmetric Standard Model

We analyze the one loop correction to $Z\rightarrow νν$ decay in framework of Minimal R-symmetric Supersymmetric Standard Model(MRSSM) in detail with normal and inverse neutrino mass orderings, as a function of $\tanβ$, Dirac mass parameters $M_D^W$ and $μ_u(μ_d)$, slepton mass $m_l$ that parameterize the mass matrices. The numerical results indicate that the branching ratio for $Z\rightarrow νν$ decay is compatible with the experimental measurement and the SM expectation at $2σ$ level. For inverse neutrino mass ordering, the prediction exceeds the SM expectation at $1σ$ level. The prediction on $Br(Z\rightarrow νν)$ increases proportionally to $\tanβ$ and inversely proportionally to $m_l$. For normal neutrino mass ordering, the peak value of the prediction on $Br(Z\rightarrow νν)$ exceeds the SM expectation at $1σ$ level.

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arXiv2019

Lepton-flavor violation and two loop electroweak corrections to $(g-2)_μ$ in the B-L symmetry SSM

Charged lepton flavor violating processes are forbidden in the standard model (SM), hence the observation of charged lepton flavor transitions would represent a clear signal of new physics beyond the standard Model. In this work, we investigate some lepton flavor violating processes in the minimal supersymmetric extension of the SM with local $B-L$ gauge symmetry (B-LSSM). And including the corrections from some two loop diagrams to the anomalous dipole moments (MDM) of muon, we discuss the corresponding constraint on the relevant parameter space of the model. Considering the constraints from updated experimental data, the numerical results show that, new contributions in the B-LSSM enhance the MSSM predictions on the rates of $l_j-l_i$ transitions about one order of magnitude, and also enhance the MSSM prediction on the muon MDM. In addition, two loop electroweak corrections can make important contributions to the muon MDM in the B-LSSM.

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arXiv2019

The four-propagator three-loop vacuum integral by the hypergeometry

Hypergeometric function method is proposed to calculate the scalar integrals of Feynman diagrams. For the scalar integral of three-loop vacuum diagram with four-propagator, we verify the equivalency of Feynman parametrization and the hypergeometric technique. The result can be described as generalized hypergeometric functions of triple variables. Based on the triple hypergeometric functions, we also establish the systems of homogeneous linear partial differential equations(PDEs) satisfied by the mentioned scalar integral. The continuation of the scalar integral from its convergent regions to whole kinematic domains can be made numerically through the system of homogeneous linear PDEs with the help of the element method.

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arXiv2018

Corrections to $R_{D}$ and $R_{D^{*}}$ in the BLMSSM

The deviation of the measurement of $R_{D}$ ($R_{D^{*}}$) from the Standard Model (SM) expectation is $2.3σ$ ($3.1σ$). $R_{D}$ ($R_{D^{*}}$) is the ratio of the branching fraction of $\overline{B} \rightarrow Dτ\overlineν_τ$ ($\overline{B} \rightarrow D^{*}τ\overlineν_τ$) to that of $\overline{B} \rightarrow Dl\overlineν_{l}$ ($\overline{B} \rightarrow D^{*}l\overlineν_{l}$), where $l = e$ or $μ$. This anomaly may imply the existence of new physics (NP). In this paper, we restudy this problem in the supersymmetric extension of the Standard Model with local gauged baryon and lepton numbers (BLMSSM), and give one-loop corrections to $R_{D}$ ($R_{D^{*}}$).

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arXiv2018

Two loop electroweak corrections to $\bar B\rightarrow X_sγ$ and $B_s^0\rightarrow μ^+μ^-$ in the B-LSSM

The rare decays $\bar B\rightarrow X_sγ$ and $B_s^0\rightarrow μ^+μ^-$ are important to research new physics beyond standard model. In this work, we investigate two loop electroweak corrections to $\bar B\rightarrow X_sγ$ and $B_s^0\rightarrow μ^+μ^-$ in the minimal supersymmetric extension of the SM with local $B-L$ gauge symmetry (B-LSSM), under a minimal flavor violating assumption for the soft breaking terms. In this framework, new particles and new definition of squarks can affect the theoretical predictions of these two processes, with respect to the MSSM. Considering the constraints from updated experimental data, the numerical results show that the B-LSSM can fit the experimental data for the branching ratios of $\bar B\rightarrow X_sγ$ and $B_s^0\rightarrow μ^+μ^-$. The results of the rare decays also further constrain the parameter space of the B-LSSM.

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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

Neutrino masses in the minimal gauged $(B-L)$ supersymmetry

We present the radiative corrections to neutrino masses in a minimal supersymmetric extension of the standard model with local $U(1)_{B-L}$ symmetry. At tree level, three tiny active neutrinos and two nearly massless sterile neutrinos can be obtained through the seesaw mechanism. Considering the one-loop corrections to the neutrino masses, the numerical results indicate that two sterile neutrinos obtain ${\rm KeV}$ masses and the small active-sterile neutrino mixing angles. The lighter sterile neutrino is a very interesting dark matter candidate in cosmology. Meanwhile the active neutrinos mixing angles and mass squared differences agree with present experimental data.

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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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