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Tai-Fu Feng

Publications and source records attributed to Tai-Fu Feng.

160 records · Page 9Linked to original sources
arXiv2004

The c-quark EDM and production of $h_c$ in $e^+e^-$ annihilation

We analyze the charm quark electric dipole moment (EDM) in the minimal supersymmetric extension of the standard model (MSSM), including important two-loop gluino contributions. Considering the experimental constraint on the neutron EDM, the theoretical prediction for the charm quark EDM can reach about $10^{-20}e\cdot cm$. If taking into account the mixing between the scharm and stop quarks in the effective supersymmetry scenario, the charm quark EDM can be enhanced to $\sim 10^{-19}e\cdot cm$. Direct production of the CP-odd $^1P_1$ state $h_c$ in $e^+e^-$ annihilation via the CP-violating process at the BES-III and CLEO-C is analyzed.

hep-ph↗
arXiv2004

Two-loop gluino contributions to neutron electric dipole moment in CP violating MSSM

We analyze two-loop gluino corrections to the neutron electric dipole moment (EDM) in the minimal supersymmetry extension of the standard model (MSSM). The dependence of two-loop corrections on the relevant CP violating phases differs from that of the one-loop contributions, and there is a region in the parameter space where the two-loop contributions are comparable with the one-loop contributions. Our numerical results show that the two-loop corrections can be as large as 30% of the one-loop results.

hep-ph↗
arXiv2004

Effective Lagrangian of the $/R$MSSM for neutrino mass generation

We derive the lepton number violating dimension-five and dimension-seven operators, relevant for neutrino mass generation, in the Minimal Supersymmetry Standard Model without R-parity (the $/R$MSSM) by using the effective Lagrangian method. We keep all the possible CP violating phases, and we establish the general relationship between the high-scale parameters and the low-energy observals associated with the Standard Model particles. We study in a specific model the dependence of neutrino masses on the CP phases.

hep-ph↗
arXiv2004

Two-loop gluino corrections to the inclusive $B\to X_{_s}γ$ decay in CP violating MSSM with large $\tanβ$

We investigate two-loop gluino corrections to the effective Lagrangian for $b\to s+γ(g)$ in the minimal supersymmetric extension of the standard model (MSSM) at large $\tanβ$, including the contributions in which quark flavor change is mediated by charginos. Using the translation invariant of loop momenta and the Ward-Takahashi identities (WTIs) that are required by the $SU(3)_c\times U(1)_{_{em}}$ gauge invariance, we simplify our expressions to concise forms. As an example, we discuss two-loop gluino corrections to the CP asymmetry of inclusive $B\to X_{_s}γ$ decay in CP violating MSSM.

hep-ph↗
arXiv2004

The anomalous Higgs-top couplings in the MSSM

The anomalous couplings of the top quark and the Higgs boson has been studied in an effective theory resulting in the framework of the minimal supersymmetric extension of the standard model (MSSM) when the heavy fields are integrated out. Constraints on the parameters of the model from the experimental data on the ratio $R_b={Γ(Z\to b\bar{b})/Γ(Z\to hadrons)}$ are derived.

hep-ph↗
arXiv2003

Lepton Dipole Moments and Rare Decays in the CP-violating MSSM with Nonuniversal Soft-Supersymmetry Breaking

We investigate the muon anomalous magnetic dipole moment (MDM), the muon electric dipole moment (EDM) and the lepton-flavour-violating decays of the $τ-$lepton, $τ\to μγ$ and $τ\to 3μ$, in the CP-violating Minimal Supersymmetric Standard Model (MSSM) with nonuniversal soft-supersymmetry breaking. We evaluate numerically the muon EDM and the branching ratios $B(τ\to μγ)$ and $B(τ\to 3μ)$, after taking into account the experimental constraints from the electron EDM and muon MDM. Upon imposition of the experimental limits on our theoretical predictions for the aforementioned branching ratios and the muon MDM, we obtain an upper bound of about $10^{-23} e\cdot cm$ on the muon EDM which lies well within the explorable reach of the proposed experiment at BNL.

hep-ph↗
arXiv2002

Neutrinoless Double Beta Decay in Supersymmetric Seesaw model

Inspired by the recent HEIDELBERG-MOSCOW double beta decay experiment, we discuss the neutrinoless double beta decay in the supersymmetric seesaw model. Our numerical analysis indicates that we can naturally explain the data of the observed neutrinoless double beta decay, as well as that of the solar and atmospheric neutrino experiments with at least one Majorana-like sneutrino of middle energy scale in the model.

hep-ph↗
arXiv2002

Lepton flavor violation decays with the fourth generation neutrino

We investigate the lepton flavor violation decays, $τ\to μγ$, $τ\to eγ$ and $μ\to eγ$, in the framwork of a squential fourth generation model with a heavy fourth neutrino, $ν'$. Using the recent experimental bounds, we can obtain the constraints of the $4\times 4$ leptonic mixing matrix element factors, $V_{1ν'},V_{2ν'}$ and $V_{3ν'}$. We find that LFV decays can give strigent costraints on the parameter space of the 4th neutrino mass $m_{ν'}$.

hep-ph↗
arXiv2001

|Delta B|=1 Weak Effective Lagrangian in the Minimal Flavor Violation Supersymmetry

To evaluate the weak decays of b-hadrons, the $ΔB=1$ weak effective Lagrangian is the foundation. Any new physics beyond the standard model (SM) would contribute to the effective Lagrangian through the loop integration at the weak scale and evolution from the weak scale down to the hadronic scale. In this work we present a systematic analysis on the effective Lagrangian which mediates hadronic $|ΔB|=1$ processes in the framework of the minimal flavor violation supersymmetry as well as a numerical evaluation of the Wilson coefficients in the effective theory.

hep-ph↗
arXiv2001

$V_{cs}$ from Pure Leptonic Decays of $D_s$ with Radiative Corrections

The radiative corrections to the pure leptonic decay $D_s{\longrightarrow} {\ell}{ν}_{\ell}$ up-to one-loop order is presented. We find the virtual photon loop corrections to $D_s{\longrightarrow} τ{ν}_τ$ is negative and the corresponding branching ratio is larger than $3.51\times 10^{-3}$. Considering the possible experimental resolutions, our prediction of the radiative decay $D_s{\longrightarrow} τ{ν}_τγ$ is not so large as others, and the best radiative channel to determine the $V_{cs}$ or $f_{D_s}$ is $D_s{\longrightarrow} μ{ν}_μγ$.

hep-ph↗
arXiv2001

The Pure Leptonic Decays of $D_s$ Meson and Their Radiative Corrections

The radiative corrections to the pure leptonic decay $D_s{\longrightarrow} {\ell}{ν}_{\ell}$ up-to one-loop order is presented. We find the virtual photon loop corrections to $D_s{\longrightarrow} τ{ν}_τ$ is negative and the corresponding branching ratio is larger than $3.51\times 10^{-3}$. Considering the possible experimental resolutions, our prediction of the radiative decay $D_s{\longrightarrow} τ{ν}_τγ$ is not so large as others, and the best channel to determine the $V_{cs}$ or $f_{D_s}$ is $D_s{\longrightarrow} μ{ν}_μγ$. How to cancel the infrared divergences appearing in the loop calculations, and the radiative decay $D_s{\longrightarrow} {\ell}{ν}_{\ell}γ$ is shown precisely. It is emphasized that the radiative decay may be separated properly and may compare with measurements directly as long as the theoretical `softness' of the photon corresponds to the experimental resolutions.

hep-ph↗
arXiv2000

Neutrino Oscillations in Supersymmetry without Lepton number conservation and R-parity

With the on-shell renormalization scheme, we discuss neutrino masses up to one-loop approximation in the Supersymmetry without lepton number conservation and R-parity. Ii is shown that in this model with experimentally allowed parameters, $Δm^2_{23}, Δm^2_{12}$ and the mixing angles $|\sinθ{23}|,|\sinθ_{12}|$ which are consistent with the present observation values can be produced. We find that small neutrino mass ($\leq$ 1 eV) sets a loose constraint on the R-parity violation parameters in the soft breaking terms.

hep-ph↗
arXiv2000

Complete analysis on the next-to-leading order supersymmetric QCD corrections to $B^0-\bar{B}^0$ mixing

We present a complete next-to-leading-order calculation of the QCD corrections to $B^0-\bar{B}^0$ ($K^0-\bar{K}^0$) mixing in the framework of the minimal flavor violating (MFV) supersymmetry. We take into account the contributions from the gluino and find that the gluino-mediated corrections modify the LO result obviously even when the mass of gluino $m_{\tilde{g}} \gg m_{\rm w}$. In general, one cannot neglect gluino contributions.

hep-ph↗
arXiv2000

The lifetime of B_c-meson and some relevant problems

The lifetime of the B_c-meson is estimated with consistent considerations on all of the heavy mesons ($B^0, B^\pm, B_s, D^0, D^\pm D_s$) and the double heavy meson B_c. In the estimate, the framework, where the non-spectator effects for nonleptonic decays are taken into account properly, is adopted, and the parameters needed to be fixed are treated carefully and determined by fitting the available data. The bound-state effects in it are also considered. We find that in decays of the meson B_c, the QCD correction terms of the penguin diagrams and the main component terms c_1O_1, c_2O_2 of the effective interaction Lagrangian have direct interference that causes an enhancement about 3 ~ 4% in the total width of the B_c meson.

hep-ph↗
arXiv2000

Search for Ambient Neutralino Dark Matter at Accelerator

We investigate the possibility of using accelarator beam particles to collide with the ambient neutralino dark matter particles in cosmic rays as a way to search for the cold dark matter. We study in detail its inelastic and elastic scattering with the projectile particles at electron-positron colliders and discuss the possible experimental signals and the relevent background.

hep-ph↗