arXiv subjects

Tai-Fu Feng

Publications and source records attributed to Tai-Fu Feng.

At least 145 records · Page 8Linked to original sources

arXiv2013

Lepton flavor violation decays of vector mesons in unparticle physics

We investigate the lepton flavor violation decays of vector mesons in the scenario of the unparticle physics by considering the constraint from $μ-e$ conversion. In unparticle physics, the predictions of LFV decays of vector mesons depend strongly on the scale dimension $d_{\mathcal{U}}$. The predictions of LFV decays of vector mesons can reach the detective sensitivity in experiment in region of $3\le d_{\mathcal{U}}\le 4$, while the prediction of $μ-e$ conversion rate can meet the experimental upper limit. For the searching of the lepton flavor violation processes of charged lepton sector in experiment, the process $Υ\rightarrow eμ$ may be a promising one to be observed.

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arXiv2013

Lepton flavor violation in inverse seesaw model

We analyze the lepton flavor violation processes $μ-e$ conversion, $l_i\rightarrow l_jγ$ and $l_i\rightarrow 3l_j$ in framework of the Standard Model (SM) extended with inverse seesaw mechanism, as a function of $\tildeη = 1 -|Det(\tilde {U}_{PMNS})|$ that parameterizes the departure from unitary of the light neutrino mixing sub-matrix $\tilde {U}_{PMNS}$. In a wide range of $\tildeη$, the predictions on the $μ-e$ conversion rates and the branching ratio of $μ\rightarrow eγ$ are sizeable to be compatible with the experimental upper limits or future experimental sensitivities. For large scale of $\tildeη$, the predictions on branching ratios of other lepton flavor processes can also be reach the experimental upper limits or future experimental sensitivities. The value of $\tildeη$ depends on the determinant of the Majorana mass term $M_μ$. Finally, searching for lepton flavor violation processes in experiment provides us more opportunities for the searches of seesaw nature of the neutrino masses.

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arXiv2013

Top Quark Forward-Backward Asymmetry in the Little Higgs Model

We calculate the forward backward asymmetry of the top-pair production at TEVATRON up to next to leading order (NLO) in the little Higgs model (LHM). We find that the contribution of $Z_H$ can be large enough to make up the gap between standard model (SM) prediction and data. With the database of $7.65\pm0.20\pm0.36$ pb, therefore, the parameter space for flavor-changing coupling of $Z_H$ is constrained. Thus this model can result in the required asymmetry while the total cross section of top-pair production remaining consistent with data.

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arXiv2013

Neutrino mixing in the $μν$SSM

Recently, several reactor oscillation experiments have successively measured a nonzero value for the neutrino mixing angle ${θ_{13}}$, which is greater than 5 standard deviations. Within framework of the $μ$ from $ν$ Supersymmetric Standard Model ($μν$SSM), three tiny neutrino masses are generated at the tree level through TeV scale seesaw mechanism. In this work, we analyze the neutrino masses and mixing in the $μν$SSM with a "top down" method, assuming neutrino mass spectrum with normal ordering (NO) or inverted ordering (IO).

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arXiv2013

Neutron electric dipole moment in CP violating BLMSSM

Considering the CP violating phases, we analyze the neutron electric dipole moment (EDM) in a CP violating supersymmetric extension of the standard model where baryon and lepton numbers are local gauge symmetries(BLMSSM). The contributions from the one loop diagrams and the Weinberg operators are taken into account. Adopting some assumptions on the relevant parameter space, we give the numerical results analysis. The numerical results for neutron EDM can reach $1.05\times 10^{-25}(e.cm)$, which is about the experimental upper limit.

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arXiv2013

Muon conversion to electron in nuclei within the $μν$SSM with a 125 GeV Higgs

Within framework of the $μ$ from $ν$ Supersymmetric Standard Model ($μν$SSM), three exotic right-handed neutrino superfields induce new sources for lepton-flavor violation. In this work, we investigate muon conversion to electron in nuclei within the $μν$SSM in detail. With a 125 GeV Higgs, the numerical results indicate that the $μ-e$ conversion rates in nuclei within the $μν$SSM can reach the experimental upper bound, which could be detected with the future experimental sensitivities.

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arXiv2013

Lepton-flavor violation and $(g-2)_μ$ in the $μν$SSM

Within framework of the $μ$ from $ν$ Supersymmetric Standard Model ($μν$SSM), exotic singlet right-handed neutrino superfields induce new sources for lepton-flavor violation. In this work, we investigate some lepton-flavor violating processes in detail in the $μν$SSM. The numerical results indicate that the branching ratios for lepton-flavor violating processes $μ\rightarrow eγ$, $τ\rightarrowμγ$ and $μ\rightarrow3e$ can reach $10^{-12}$ when $\tanβ$ is large enough, which can be detected in near future. We also discuss the constraint on the relevant parameter space of the model from the muon anomalous magnetic dipole moment. In addition, from the scalars for the $μν$SSM we strictly separate the Goldstone bosons, which disappear in the physical gauge.

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arXiv2013

t-c gamma and t-cg in warped extra dimensions

In this work, we calculate the top quark rare decays t-cgamma and t-cg in the framework where the standard model is embedded in a warped extra dimension with the custodial symmetry SU(3)c*SU(2)L*SU(2)R*U(1)x*PLR. Adopting reasonable assumptions on the parameter space,we numerically find the branching ratios of t-cgamma exceeding 10^-6 and that of t-cg exceeding 10^-5 respectively, which can be detected in near future.

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arXiv2013

Gauged baryon and lepton numbers in supersymmetry with a $125\;{\rm GeV}$ Higgs

Assuming that the Yukawa couplings between the Higgs and exotic quarks cannot be ignored, we analyze the signals of decay channels $h\rightarrowγγ$ and $h\rightarrow VV^*\;(V=Z,\;W)$ with the Higgs mass around $125\;{\rm GeV}$ in a supersymmetric extension of the standard model where baryon and lepton numbers are local gauge symmetries. Adopting some assumptions on relevant parameter space, we can account for the experimental data on Higgs from ATLAS and CMS naturally.

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arXiv2012

Search for lepton flavor violation in supersymmetric models via meson decays

Considering the constraints from the experimental data on $μ\rightarrow eγ$, $μ\rightarrow3e$, $μ-e$ conversion etc., we analyze the Lepton Flavor Violating decays $ϕ(J/Ψ,Υ(1S)) \rightarrow e^+μ^-(μ^+τ^-)$ in the scenarios of the minimal supersymmetric extensions of Standard Model with seesaw Mechanism. Numerically, there is parameter space that the LFV processes of $J/Ψ(Υ)\rightarrowμ^+τ^-$ can reach the upper experimental bounds, meanwhile the theoretical predictions on $μ\rightarrow eγ$, $μ\rightarrow3e$, $μ-e$ conversion satisfy the present experimental bounds. For searching of new physics, Lepton Flavor Violating processes $J/Ψ(Υ)\rightarrowμ^+τ^-$ may be more promising and effective channels.

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arXiv2011

Residue theorem and summing over Kaluza-Klein excitations

Applying the equations of motion together with corresponding boundary conditions of bulk profiles at infrared and ultraviolet branes, we verify some lemmas on the eigenvalues of Kaluze-Klein modes in framework of warped extra dimension with the custodial symmetry $SU(3)_c\times SU(2)_L\times SU(2)_R\times U(1)_X\times P_{LR}$. Using the lemmas and performing properly analytic extensions of bulk profiles, we present the sufficient condition for a convergent series of Kaluze-Klein excitations and sum over the series through the residue theorem. The method can also be applied to sum over the infinite series of Kaluze-Klein excitations in unified extra dimension. Additional, we analyze the possible connection between the propagators in five dimensional full theory and the product of bulk profiles with corresponding propagators of exciting Kaluze-Klein modes in four dimensional effective theory, and recover some relations presented in literature for warped and unified extra dimensions respectively. As an example, we demonstrate that the corrections from neutral Higgs to the Wilson coefficients of relevant operators for $B\rightarrow X_sγ$ contain the suppression factor $m_b^3m_s/m_{_{\rm w}}^4$ comparing with that from other sectors, thus can be neglected safely.

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arXiv2010

Heavy fermions and two loop electroweak corrections to $b\rightarrow s+γ$

Applying effective Lagrangian method and on-shell scheme, we analyze the electroweak corrections to the rare decay $b\rightarrow s+γ$ from some special two loop diagrams in which a closed heavy fermion loop is attached to the virtual charged gauge bosons or Higgs. At the decoupling limit where the virtual fermions in inner loop are much heavier than the electroweak scale, we verify the final results satisfying the decoupling theorem explicitly when the interactions among Higgs and heavy fermions do not contain the nondecoupling couplings. Adopting the universal assumptions on the relevant couplings and mass spectrum of new physics, we find that the relative corrections from those two loop diagrams to the SM theoretical prediction on the branching ratio of $B\rightarrow X_{_s}γ$ can reach 5% as the energy scale of new physics $Λ_{_{\rm NP}}=200$ GeV.

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arXiv2009

Renormalization and two loop electroweak corrections to lepton anomalous dipole moments in the standard model and beyond (I): heavy fermion contributions

Applying effective Lagrangian method and on-shell scheme, we analyze the electroweak corrections to anomalous dipole moments of lepton from some special two loop diagrams in which a closed heavy fermion loop is attached to the virtual gauge bosons or Higgs fields. As the masses of virtual fermions in inner loop are much heavier than the electroweak scale, we verify the final results satisfying the decoupling theorem explicitly if the interactions among Higgs and heavy fermions do not contain the nondecoupling couplings. At the decoupling limit, we also present the leading corrections to lepton anomalous dipole moments from those two loop diagrams in some popular extensions of the standard model, such as the fourth generation, supersymmetry, universal extra dimension, and the littlest Higgs with T-parity.

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arXiv2008

Electroweak and supersymmetric two-loop corrections to lepton anomalous magnetic and electric dipole moments

Using the effective Lagrangian method, we analyze the electroweak corrections to the anomalous dipole moments of lepton from some special two-loop diagrams where a closed neutralino/chargino loop is inserted into relevant two Higgs doublet one-loop diagrams in the minimal supersymmetric extension of the standard model with CP violation. Considering the translational invariance of loop momenta and the electromagnetic gauge invariance, we get all dimension 6 operators and derive their coefficients. After applying equations of motion to the external leptons, we obtain the anomalous dipole moments of lepton. The numerical results imply that there is parameter space where the contributions to the muon anomalous dipole moments from this sector may be significant.

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arXiv2008

The two loop supersymmetric corrections to lepton anomalous dipole moments in split supersymmetry scenarios

An analysis of electroweak corrections to the anomalous dipole moments of lepton from some special two-loop diagrams where a closed neutralino/chargino loop is inserted into relevant one-loop diagrams of the standard model is presented in the split supersymmetry scenarios. Considering the translational invariance of the inner loop momenta and the electromagnetic gauge invariance, we get all dimension 6 operators and their coefficients. After applying equations of motion to the external leptons, we obtain the anomalous dipole moments of lepton. The numerical results imply that there is parameter space where the contribution to the muon anomalous magnetic dipole moment from this sector is perhaps significant, and the contribution to the electron electric dipole moment from this sector is sizable enough to be observed in next generation experiments.

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arXiv2006

Detecting the ambient neutralino dark matter particles at accelerator

In this work, we present a new strategy to investigate the possibility of direct detection of the ambient neutralino matter at accelerator. We calculate the cross sections for both elastic and inelastic scattering processes of the dark matter particles with the beam particles at $e^+e^-$ and hadron colliders.

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arXiv2006

The two-loop supersymmetric corrections to lepton anomalous magnetic and electric dipole moments

Using the effective Lagrangian method, we analyze the electroweak corrections to the anomalous dipole moments of lepton from some special two-loop topological diagrams which are composed of neutralino (chargino) - slepton (sneutrino) in the minimal supersymmetric extension of the standard model (MSSM). Considering the translational invariance of the inner loop momenta and the electromagnetic gauge invariance, we get all dimension 6 operators and derive their coefficients. After applying equations of motion to the external leptons, the anomalous dipole moments of lepton are obtained. The numerical results imply that there is a parameter space where the two-loop supersymmetric corrections to the muon anomalous dipole moments may be significant.

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arXiv2006

Mixing among the neutral Higgs bosons and rare B decays in the CP violating MSSM

Considering corrections from two-loop Feynman diagrams which involve gluino at large $\tanβ$, we analyze the effects of possible CP phases on the rare B decays: $\bar{B}_{_{s}} \to l^+l^-$ and $\bar{B}\to Kl^+l^-$ in the CP violating minimal supersymmetric extension of the standard model. It is shown that the results of exact two loop calculations obviously differ from that including one-loop contributions plus threshold radiative corrections. The numerical analysis indicates that the possibly large CP phases strongly affect the theoretical estimation of the branching ratios, and this results coincide with the conclusion of some other works appearing in recent literature.

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