arXiv subjects

Tai-Fu Feng

Publications and source records attributed to Tai-Fu Feng.

At least 91 records · Page 5Linked to original sources

arXiv2021

Gravitational waves from the phase transition in the B-LSSM

Based on the gauge symmetry group $SU(3)_C\otimes{SU(2)_L}\otimes{U(1)_Y}\otimes{U(1)_{B-L}}$, the minimal supersymmetric extension of the SM with local B-L gauge symmetry(B-LSSM) has been introduced. In this model, we study the Higgs masses with the one-loop zero temperature effective potential corrections. Besides, the finite temperature effective potentials connected with two $U(1)_{B-L}$ Higgs singlets are deduced specifically. Then we can obtain the gravitational wave spectrums generated from the strong first-order phase transition. In the B-LSSM, the gravitational wave signals can be as strong as $h^2Ω_{GW}\sim10^{-11}$, which may be detectable in the future experiments.

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arXiv2021

Scalar neutrino dark matter in BLMSSM

BLMSSM is the extension of the minimal supersymmetric standard model(MSSM). Its local gauge group is $SU(3)_C \times SU(2)_L \times U(1)_Y \times U(1)_B \times U(1)_L$. Supposing the lightest scalar neutrino is dark matter candidate, we study the relic density and the spin independent cross section of sneutrino scattering off nucleon. We calculate the numerical results in detail and find suitable parameter space. The numerical discussion can confine the parameter space and provide a reference for dark matter research.

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arXiv2021

Higgs boson decays with lepton flavor violation in the $B-L$ symmetric SSM

Recently, the ATLAS and CMS Collaborations reported the latest experimental upper limits on the branching ratios of the lepton flavor violating (LFV) 125 GeV Higgs boson decays, $h\rightarrow eμ$, $h\rightarrow eτ$, and $h\rightarrow μτ$. In this paper, we mainly investigate the LFV Higgs boson decays $h\rightarrow eμ$, $h\rightarrow eτ$, and $h\rightarrow μτ$ in the minimal supersymmetric extension of the Standard Model with local $\emph{B-L}$ gauge symmetry. At the same time, the corresponding constraints from the LFV rare decays $μ\rightarrow eγ$, $τ\rightarrow eγ$, $τ\rightarrow μγ$, and muon $(g-2)$ are considered to analyze the numerical results.

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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.

hep-ph↗

arXiv2021

The two-loop contributions to muon MDM in $U(1)_X$ SSM

The MSSM is extended to the $U(1)_X$SSM, whose local gauge group is $SU(3)_C \times SU(2)_L \times U(1)_Y \times U(1)_X$. To obtain the $U(1)_X$SSM, we add the new superfields to the MSSM, namely: three Higgs singlets $\hatη,~\hat{\barη},~\hat{S}$ and right-handed neutrinos $\hatν_i$. It can give light neutrino tiny mass at the tree level through the seesaw mechanism. The study of the contribution of the two-loop diagrams to the MDM of muon under $U(1)_X$SSM provides the possibility for us to search for new physics. In the analytical calculation of the loop diagrams (one-loop and two-loop diagrams), the effective Lagrangian method is used to derive muon MDM. Here, the considered two-loop diagrams include Barr-Zee type diagrams and rainbow type two-loop diagrams, especially Z-Z rainbow two-loop diagram is taken into account. The obtained numerical results can reach $7.4\times10^{-10}$, which can remedy the deviation between SM prediction and experimental data to some extent.

hep-ph↗

arXiv2020

125 GeV Higgs boson decay to a pair of muons in the $μν$SSM

Recently, the ATLAS and CMS Collaborations measured the 125 GeV Higgs boson decay to a pair of muons $h\rightarrow μ\barμ$, which reported the signal strength relative to the standard model (SM) prediction is $1.2\pm0.6$ and $1.19^{+0.40+0.15}_{-0.39-0.14}$, respectively. In this work, we investigate the 125 GeV Higgs boson decay $h\rightarrow μ\barμ$ at one-loop level in the $μ$ from $ν$ Supersymmetric Standard Model ($μν$SSM). Compared to the SM prediction, the decay width of $h\rightarrow μ\barμ$ in the $μν$SSM can boost up about 10\%, considering the constraint from the muon anomalous magnetic dipole moment.

hep-ph↗

arXiv2020

$\bar{B}\to X_s γ$ in BLMSSM

Applying the effective Lagrangian method, we study the Flavor Changing Neutral Current $b\to sγ$ within the minimal supersymmetric extension of the standard model where baryon and lepton numbers are local gauge symmetries. Constraints on the parameters are investigated numerically with the experimental data on branching ratio of $\bar{B}\to X_sγ$. Additionally, we present the corrections to direct CP-violation in $\bar{B}\rightarrow X_sγ$ and time-dependent CP-asymmetry in $B\rightarrow K^*γ$. With appropriate assumptions on parameters, we find the direct CP-violation $A_{CP}$ is very small, while one-loop contributions to $S_{K^*γ}$ can be significant.

hep-ph↗

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.

hep-ph↗

arXiv2020

Mass spectra of heavy pseudoscalars using instantaneous Bethe-Salpeter equation with different kernels

We solved the instantaneous Bethe-Salpeter equation for heavy pseudoscalars in different kernels, where the kernels are obtained using linear scalar potential plus one gluon exchange vector potentials in Feynman gauge, Landau gauge, Coulomb gauge and time-component Coulomb gauge. We obtained the mass spectra of heavy pseudoscalars, and compared the results between different kernels, found that using the same parameters we obtain the smallest mass splitting in time-component Coulomb gauge, the similar largest mass splitting in Feynman and Coulomb gauges, middle size splitting in Landau gauge.

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arXiv2020

Average speed and its powers $v^n$ of a heavy quark in quarkonia

The typical velocity of a heavy quark in a quarkonium is a widely used quantity, in this paper, based on the relativistic Bethe-Salpeter equation method, we calculate the average values ${\overline{|\boldsymbol{q}|^n}}$ and $ \overline{|\boldsymbol{v}|^n}\equiv v^n$ of a heavy quark in a $S$ wave or $P$ wave quarkonium rest frame, where $\boldsymbol{q}$ and $\boldsymbol{v}$ are the three dimensional momentum and velocity, $n=1,2,3,4$. For a charm quark in $J/ψ$, we obtained $v_{J/ψ}=0.46$, $v^2_{J/ψ}=0.26$, $v^3_{J/ψ}=0.18$, and $v^4_{J/ψ}=0.14$, for a bottom quark in $Υ(1S)$, $v_{Υ(1S)}=0.24$, $v^2_{Υ(1S)}=0.072$, $v^3_{Υ(1S)}=0.025$, and $v^4_{Υ(1S)}=0.010$. The values indicate that ${v^n} >{v^{n_1}}\cdot{v^{n_2}}$, where $n_1+n_2=n$, which is correct for all the charmonia and bottomonia. Our results also show the poor convergence if we make the {speed} expansion in charmonium system, but good for bottomonium. Based on the $v^n$ values and the following obtained relations $v^n_{4S} > v^n_{3S}> v^n_{2S}>v^n_{1S}$, $v^n_{4P} > v^n_{3P}> v^n_{2P}>v^n_{1P}$ and $v^n_{mP}>v^n_{mS}$ ($n,m=1,2,3,4$), we conclude that highly excited quarkonia have larger relativistic corrections than those of the corresponding low excited and ground states, and there are large relativistic corrections in charmonium system.

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arXiv2020

The naturalness in the BLMSSM and B-LSSM

In order to interpret the Higgs mass and its decays more naturally, we hope to intrude the BLMSSM and B-LSSM. In the both models, the right-handed neutrino superfields are introduced to better explain the neutrino mass problems. In addition, there are other superfields considered to make these models more natural than MSSM. In this paper, the method of $χ^2$ analyses will be adopted in the BLMSSM and B-LSSM to calculate the Higgs mass, Higgs decays and muon $g-2$. With the fine-tuning in the region $0.67\%-2.5\%$ and $0.67\%-5\%$, we can obtain the reasonable theoretical values that are in accordance with the experimental results respectively in the BLMSSM and B-LSSM. Meanwhile, the best-fitted benchmark points in the BLMSSM and B-LSSM will be acquired at minimal $(χ^{BL}_{min})^2 = 2.34736$ and $(χ^{B-L}_{min})^2 = 2.47754$, respectively.

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arXiv2020

Electron and muon $(g-2)$ in the B-LSSM

The theoretical predictions in the standard model (SM) and measurements on the anomalous magnetic dipole moments (MDM) of muon and electron have great precision, hence the MDMs of muon and electron have close relation with the new physics (NP) beyond the SM. Recently, a negative $\sim2.4σ$ discrepancy between the measured electron MDM and the SM prediction results from a recent improved determination of the fine structure constant. Combined with the long-lasting muon MDM discrepancy which is about $\sim3.7σ$, it is difficult to explain both the magnitude and opposite signs of the deviations in a consistent model, without introducing large flavour-violating effects. The analysis shows that they can be explained in the minimal supersymmetric extension (MSSM) of the SM with local $B-L$ gauge symmetry (B-LSSM). Comparing with the MSSM, new parameters in the B-LSSM can affect the theoretical predictions on lepton MDMs, and the effects of them are explored.

hep-ph↗

arXiv2020

Higgs boson decay $h\rightarrow Zγ$ and muon magnetic dipole moment in the $μν$SSM

To solve the $μ$ problem and generate three tiny neutrino masses in the MSSM, the $μ$ from $ν$ Supersymmetric Standard Model ($μν$SSM) introduces three singlet right-handed neutrino superfields, which lead to the mixing of the Higgs doublets with the sneutrinos. The mixing affects the lightest Higgs boson mass and the Higgs couplings. The present observed 95\% CL upper limit on signal strength of the 125 GeV Higgs boson decay $h\rightarrow Zγ$ is 6.6, which still is plenty of space to prove the existence of new physics. In this work, we investigate the signal strength of the 125 GeV Higgs boson decay channel $h\rightarrow Zγ$ in the $μν$SSM. Besides, we consider the two-loop electroweak corrections of muon anomalous magnetic dipole moment (MDM) in the model, which also make important contributions compared with one-loop electroweak corrections.

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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.

hep-ph↗

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.

hep-ph↗

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.

hep-th↗

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.

hep-ph↗

arXiv2019

A proposal on complementary determination of the electro-weak mixing angles ${\rm sin^2θ_W}$ at a super Z-factory

A proposal on determination of the effective electro-weak mixing angle ${\rm sin^2θ_{eff}^f\;(f=c,b)}$ at a super Z-factory (an $e^+e^-$ collider designed with the possible highest luminosity and running around the center mass energy $\sqrt s=m_Z$) is proposed. It is to determine how the effective mixing angles depend on the flavors, especially the flavors $c$, $b$ (with the determined effective ones, the electro-weak mixing angles ${\rm sin^2θ_W^f\;(f=c,b)}$ of Standard Model can be derived out precisely). The key point of the proposal is that at such a super Z-factory, via measuring the forward-backward ($A_{FB}$), left-right ($A_{LR}$) and combined left-right forward-backward ($A^{FB}_{LR}$) asymmetries of the produced doubly heavy-flavored hadrons (such as $B_c$, $B_c^*$ and the baryons $H_{QQ'q}$: $Ξ_{cc}$, $Ξ_{bc}$ and $Ξ_{bb}$ etc) in the relevant production processes $e^+e^-\to B_c+\cdots$ and $e^+e^-\to H_{QQ'q}+\cdots$ one may complement the final determination of the mixing angle ${\rm sin^2θ_W^f\;(f=c,b)}$ of Standard Model. The advantage of the proposed way to determine the effective electro-weak mixing angles is that the doubly heavy flavor(s) and the out-going direction of the produced doubly-heavy hadron can be experimental determined precisely, i.e. there are no such errors caused by missing identification of the heavy flavor(s) and by determining the so-called thrust axis of the produced jets, which can not be avoided in the early determination at LEP-I and SLC.

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