arXiv subjects

Tai-Fu Feng

Publications and source records attributed to Tai-Fu Feng.

At least 19 recordsLinked to original sources

arXiv2026

Top-quark flavor-changing neutral currents and charged-lepton flavor violation in a generational three-Higgs-doublet model

In this work, we systematically investigate top-quark flavor-changing neutral-current decays, charged-lepton flavor-violating processes, and coherent $\mu-e$ conversion in the CP-conserving generational three-Higgs-doublet model (G3HDM), including the relevant tree-level and one-loop contributions. The 4839-point sample passes conservative sufficient vacuum-stability conditions, necessary perturbative-unitarity preselection cuts, Higgs-mass and signal-strength constraints, electroweak precision data, the UTfit 2025 neutral-meson-mixing ranges, $\overline{B}\to X_s\gamma$, and $B_s\to\mu^+\mu^-$. In the scanned region, $\mathrm{Br}(t\to c h_1)\leq 1.04\times10^{-5}$ and $\mathrm{Br}(h_1\to\mu\tau)\leq 4.83\times10^{-4}$, while the maximal conversion rates are $\mathrm{CR}(\mu\mathrm{Al}\to e\mathrm{Al})\approx 4.95\times10^{-15}$ and $\mathrm{CR}(\mu\mathrm{Au}\to e\mathrm{Au})\approx 1.05\times10^{-14}$. The dominant collider signals are mainly driven by tree-level flavor-changing neutral-Higgs couplings, which determine the relative strengths of these processes and induce the pronounced enhancement of $t\to c h_1$ and $h_1\to\mu\tau$. Meanwhile, the upper range of the predicted $\mu-e$ conversion rate in aluminum lies within the sensitivity reach of next-generation $\mu-e$ conversion experiments.

hep-ph↗

arXiv2026

Electric Dipole Moments in the CP-violating Generational Three-Higgs-Doublet Model

Motivated by the Yukawa interactions in the CP-violating Generational Three-Higgs-Doublet Model (G3HDM), we investigate the electric dipole moments (EDMs) of the $b$ quark, $c$ quark, electron, neutron, and mercury atom, imposing constraints from the observed $125~\mathrm{GeV}$ Higgs signals, flavor physics, and rare $B$-meson decays. We find that the $b$ quark, neutron, and mercury EDMs are predominantly controlled by top-enhanced charged-Higgs amplitudes, whose internal cancellations are generally weak. Meanwhile, pronounced pairwise cancellations between nearly degenerate neutral Higgs states occur in the $c$ quark, electron, neutron, and mercury EDMs. Using degenerate perturbation theory, we show that these cancellations originate from approximate relations among the neutral-Higgs mixing-matrix elements, which enforce the anti-alignment of the corresponding CP-odd coupling invariants.

hep-ph↗

arXiv2026

Flavor-Violating Higgs and Top Decays in the Type 1B Flavorful Two-Higgs-Doublet Model with a Twist

We study flavor-violating decays of the SM-like Higgs boson and rare top decays in the Type 1B realization of the flavorful two-Higgs-doublet model with a twist, focusing on $h\to sb$, $h\to db$, $h\to uc$, $h\to\mu\tau$, $h\to e\tau$, $h\to e\mu$, $t\to ch$, and $t\to uh$. We present the relevant amplitude and branching-ratio formulae, include one-loop vertex corrections, and impose constraints from Higgs signal-strength measurements, electroweak precision tests, meson mixing, $B\to X_s\gamma$, direct HFV searches and CLFV constraints, including $\mu-e$ conversion. The surviving parameter space favors $\mathrm{BR}(h\to sb)\gg\mathrm{BR}(h\to db)$, $\mathrm{BR}(t\to ch)\gg\mathrm{BR}(t\to uh)$, and $\mathrm{BR}(h\to\mu\tau)\gg\mathrm{BR}(h\to e\tau)\sim\mathrm{BR}(h\to e\mu)$ in the lepton sector. One-loop effects usually preserve these hierarchies, but can modify individual channels through different mechanisms: sizable destructive tree--loop interference can reduce $h\to sb$ enough to yield rare $\mathrm{BR}_{\mathrm{1L}}(h\to db)>\mathrm{BR}_{\mathrm{1L}}(h\to sb)$ points, whereas the large relative corrections found in rare top decays mainly reflect strong SM-like alignment suppressing the tree-level amplitudes.

hep-ph↗

arXiv2026

The Higgs boson decay $h \to bs$ in the Generational Three-Higgs-Doublet Model

The Generational Three-Higgs-Doublet Model (G3HDM) extends the Standard Model (SM) by three Higgs doublets, which couple separately to different generations of quarks and charged leptons, and consequently make significant contributions to the neutral flavor-changing processes. Considering the latest experimental constraints on $125\mathrm{GeV}$ Higgs signals, electroweak precision observables, neutral-meson mixing, and the rare decay processes $B\to X_s\gamma$ and $B_s^0\to\mu^+\mu^-$, we perform a systematic analysis of the processes $h \to bs$ predicted in the G3HDM. This process is strongly suppressed by the loop factor in the SM, hence any observation of $h \to bs$ in the near future provides a sensitive probe of physics beyond the SM. Finally, the constraints on the parameter space and the experimental testability of G3HDM through observation $h \to bs$ are presented.

hep-ph↗

arXiv2026

The Higgs boson decay $h \rightarrow bs$ in the NB-LSSM

Within the framework of the next to minimum B-L supersymmetric model (NB-LSSM), we investigate the flavor transition process $\bar B\rightarrow X_s\gamma$. Building upon this foundation, we further discuss the Higgs decay process $h \to bs$ under the constraint from the $\bar B\rightarrow X_s\gamma$ process. Our study reveals that the branching ratio of $h \to bs$ can significantly deviate from the Standard Model (SM) expectation, depending on the values of the new parameters introduced in the model. This finding highlights the modulation of new physics parameters on the Higgs flavor-violating decay and provides important theoretical grounds for exploring new physics beyond the SM through flavor observables.

hep-ph↗

arXiv2026

$B \to X_{\mathrm{s}} l^{+} l^{-}$ in the $\mu$ from $\nu$ Supersymmetric Standard Model

We investigate the impact of new physics on the rare inclusive decay $B \to X_{\mathrm{s}} l^{+} l^{-}$ within the framework of the $\mu$ from $\nu$ Supersymmetric Standard Model ($\mu\nu$SSM). The dominant contributions to the relevant Wilson coefficients and their corresponding particles are identified and analyzed. By performing a systematic scan over the relevant parameter space, we elucidate the underlying physical mechanisms governing these dominant contributions and demonstrate their consistency with the experimentally allowed regions. Experimental constraints from the decays $\bar{B} \to X_{\mathrm{s}}\gamma$, $B_{\mathrm{s}}^{0} \to \mu^{+} \mu^{-}$, and the $125\,\text{GeV}$ SM-like Higgs boson are also incorporated. We perform a systematic interference decomposition of the Wilson-coefficient contributions to the forward-backward asymmetry, identifying the $C_7C_{10}$ and $C_9C_{10}$ interference terms as the dominant contributions governing its behavior in both the low- and high-$q^2$ regions.

hep-ph↗

arXiv2026

Controlling Quantum discord and steering in Electron-Positron Annihilation Using Polarized Beams

Quantum discord and steering offer crucial insights into the non-classical nature of hyperon-antihyperon pairs, a massive two-qubit system produced in high energy electron-positron annihilation. This work theoretically investigates the generation and control of these quantum correlations by leveraging longitudinal and transverse polarization of lepton beams. By exploiting the joint spin density matrix of hyperon pairs, the sensitivity of quantum discord and steering to the beam polarization degree are numerically quantified. Our analysis reveals distinct angular regimes where beam polarization can enhance steering and discord. Hierarchy of different quantum correlations are examined under the case of polarized lepton beams by constructing a measure in the spirit of entanglement of formation. It is confirmed that quantum discord remain non-zero even in regions with vanishing entanglement corresponding to separable states, controlled via transversely polarized beams. As an experimentally tunable parameter, beam polarization offers an effective means to manipulate the quantum correlation of hyperon-antihyperon systems, thereby providing a practical route for preparing and probing quantum states in high-energy particle physics.

hep-ph↗

arXiv2026

Strong decays of the hidden-charm molecular pentaquarks

We investigate the strong decays of the recently observed hidden-charm pentaquarks $P_{\psi}^N(4312)$, $P_{\psi}^N(4440)$, and $P_{\psi}^N(4457)$, as well as $P_{\psi s}^\Lambda(4338)$ and $P_{\psi s}^\Lambda(4459)$, within the molecular framework using the effective Lagrangian approach. We construct the effective Lagrangians describing the S-wave couplings between these pentaquarks and their constituent hadrons, namely $\Sigma_c\bar{D}^{(*)}$ and $\Xi_c\bar{D}^{(*)}$, and determine the coupling constants via the residues of the scattering $T$-matrix at the bound-state poles. Our results show that the decay widths are sensitive to the cutoff parameters in the form factors, whereas the branching fractions exhibit only weak dependence. Using $P_{\psi}^N(4312)$ to calibrate the cutoff range, we further explore the spin assignments of $P_{\psi}^N(4440)$ and $P_{\psi}^N(4457)$. Our calculations favor the assignment where the lower-mass state $P_{\psi}^N(4440)$ carries higher spin $J = 3/2$ and the higher-mass state $P_{\psi}^N(4457)$ carries lower spin $J = 1/2$. In addition, the experimental widths of $P_{\psi s}^\Lambda(4338)$ and $P_{\psi s}^\Lambda(4459)$ can both be well reproduced under the molecular interpretation. We look forward to future experimental analyses with more accumulated data to clarify whether the lineshape of $P_{\psi s}^\Lambda(4459)$ contains contributions from both spin-$1/2$ and spin-$3/2$ states.

hep-ph↗

arXiv2026

The Higgs boson in the CP-violating NB-LSSM

This study investigates the lightest and second-lightest Higgs bosons at around 95 GeV (which is only a hypothetical scenario) and 125 GeV respectively within the CP-violating next to minimum B-L supersymmetric model(NB-LSSM). In the NB-LSSM, the CP violation in the Higgs potential leads to the mixing mass terms between the CP-even and CP-odd Higgs fields. Thus, one has to consider a $(10 \times 10)$-dimensional mass matrix for the neutral Higgs boson. These potential mixing effects may lead to drastic variations on the neutral Higgs boson masses. Besides, the neutral Higgs bosons predicted in the NB-LSSM may strongly mix with one another, thereby significantly modifying the couplings of the Higgs bosons to the fermions or gauge bosons. It is found that the specific parameters $g_{YB}$, $\tan\beta$, $T_\kappa$, $T_\lambda, \cdot\cdot\cdot$ and CP-violating phases $\theta_{1,2,3,4,6,7,8}$ in the NB-LSSM affect the theoretical predictions on the Higgs boson mass and corresponding signal strengthes significantly. And the theoretical predictions on the signal strengthes of SM-like Higgs decay channels and excess signals at around 95 GeV are fitted well to the observed experimental data.

hep-ph↗

arXiv2026

The 95 GeV and 125 GeV Higgs Excesses in the Left-Right Supersymmetric Standard Model

This study investigates the excesses observed around 95 GeV in diphoton and $b\bar{b}$ experiments within the framework of the Left-Right Supersymmetric Model (LRSSM). Considering the one-loop and two-loop effective potential corrections to the Higgs masses, the model is able to describe the experimentally observed $\mu(h_{95})_{\gamma\gamma}$ and $\mu(h_{95})_{b\bar{b}}$ signal strengths. In addition, we also present the impacts of the LRSSM-specific parameters $\tan\beta_{R}$, $v_{R}$ and $v_{S}$ on the theoretical predictions of the signal strengths for the 95 GeV and 125 GeV neutral Higgs both.

hep-ph↗

arXiv2026

Manipulating Bell nonlocality and entanglement in polarized electron-positron annihilation

The hyperon-antihyperon pairs produced in electron-positron annihilation as a massive two-qubit quantum system can be used to study the quantum correlations at high energies. This paper is theoretically dedicated to how polarization of lepton beams manipulate the Bell nonlocality and entanglement of hyperon pairs system. The response of CHSH parameter, concurrence, and negativity to the polarization degree of beam is numerically calculated by exploiting the joint spin density matrix of hyperon-antihyperon pairs. Different influences of longitudinal and transverse polarization of beams on entanglement are found and compared. The results provide alternative perspectives for the decay of charmonium to hyperon pairs.

hep-ph↗

arXiv2026

$S-P-D$ Mixing in Vector Quarkonia from the Salpeter Equation with Optimized Wave Function Representations

This paper proposes a novel mechanism based on the instantaneous Bethe-Salpeter (Salpeter) equation for investigating wave function mixing in vector mesons such as $\psi(3770)$. Conventional theories typically treat $\psi(3770)$ as a $2S-1D$ mixed state; however, considering only tensor forces or relativistic corrections alone often leads to mixing angles that are too small and inconsistent with experimental data. Phenomenological $2S-1D$ mixing requires experimental data as input to determine the mixing angles, resulting in limited theoretical studies on states like $\Upsilon(1D, 2D)$ in the absence of experimental data. To more accurately describe $S-D$ mixing and its relativistic effects, this paper systematically compares four relativistic wave function representations ($\varphi_1$, $\varphi_2$, $\varphi_3$, and $\varphi_4$) by solving the Salpeter equation and calculates the mass spectra and dileptonic decay widths of charmonium and bottomonium. The study finds that the wave function representation $\varphi_2$ can simultaneously reproduce the experimental data of both charmonium and bottomonium well. Further analysis reveals that, in addition to $S-D$ mixing, the wave functions of vector mesons contain a non-negligible $P$-wave component, meaning they are $S-P-D$ mixed states. We predict the mixing angles for bottomonium $\Upsilon(1D)$ and $\Upsilon(2D)$ to be $(1.78^{+0.32}_{-0.25})^\circ$ and $(5.44^{+1.10}_{-0.76})^\circ$, with dileptonic decay widths of $2.29^{+0.86}_{-0.69}$ eV and $10.5^{+4.2}_{-3.1}$ eV, respectively.

hep-ph↗

arXiv2026

Resolved photoproduction of the $B_c$ meson in electron-proton collisions

We present a systematic study of $B_c$ meson photoproduction at electron--proton colliders within the framework of nonrelativistic QCD (NRQCD) factorization. In addition to the dominant direct channel $\gamma+g\to B_c+X$, we include resolved contributions initiated by $g+g$ and $q+\bar q (q=u,d,s)$ subprocesses. Total cross sections and transverse-momentum distributions are calculated for several collider configurations, including HERA, LHeC, FCC-$ep$, and EIC. The numerical results show that the direct $\gamma+g$ channel provides the leading contribution over the entire kinematic range. However, the resolved $g+g$ channel yields a non-negligible correction, reaching the level of $\mathcal{O}(10\%)$ in the low-$p_T$ region where most events are produced, and it becomes increasingly important at higher collision energies. The $q+\bar q$ channel is found to be numerically insignificant.

hep-ph↗

arXiv2025

Lepton-flavor violation in the MRSSMSeesaw

The Minimal R-symmetric Supersymmetric Standard Model with Seesaw (MRSSMSeesaw) extends the MRSSM by incorporating right-handed neutrinos to generate neutrino masses via the Type-I seesaw mechanism. This work presents a detailed analysis of lepton flavor violation (LFV) processes, including $\ell_i \rightarrow \ell_j \gamma$, $\ell_i \rightarrow 3\ell_j$, and Higgs decays $h \rightarrow \ell_i \ell_j$, Based on the current experimental limitations, we carry out detailed parameter scanning and numerical calculations to analyse the effects of different sensitive parameters on LFV.The numerical results show that the non-diagonal elements involving the initial and final leptons are main sensitive parameters and LFV sources.

hep-ph↗

arXiv2025

125 GeV Higgs boson rare decays in a flavor-dependent $U(1)_F$ model

In this work, we analyze the Higgs boson decay channels, specifically, $h{\rightarrow}\gamma\gamma$, $h{\rightarrow} VV^*$ (with $V=Z,W$), and $h{\rightarrow} f\bar{f}$ (for $f=b,c,\tau$) within the flavor-dependent $U(1)_F$ model (FDM). We also investigate processes induced by flavor-changing neutral currents, including the decays $\bar B \to X_s\gamma$ and $B_s^0 \to \mu^+\mu^-$, the top quark decays $t\to c h$ and $t\to u h$, and the lepton flavor-violating decays $\tau \to 3e$, $\tau \to 3\mu$, and $\mu \to 3e$. Furthermore, we incorporate the electroweak precision observables constraints via the S, T, and U parameters. Compared to the Standard Model, the scalar sector of the FDM is extended by two Higgs doublets and one Higgs singlet, which affects the 125 GeV Higgs properties significantly. Meanwhile, the decays $h{\rightarrow} Z\gamma$, $h\rightarrow MZ$, and $h{\rightarrow} M\gamma$ (where $M$ is a vector meson $(\rho,\omega,\phi,J/\Psi,\Upsilon)$ of the Standard-Model-like Higgs are studied, and we illustrate how changes in the scalar sector and the Yukawa coupling influence the signal strengths for the 125 GeV Higgs decay channels and the Higgs mass in the FDM.

hep-ph↗

arXiv2025

Relativistic Bethe-Salpeter study of OZI-rule allowed strong decays: determination of total width of $h_{c}(2P)$ and $^{3}P_{0}$ model parameter

Strong decays allowed by the Okubo-Zweig-Iizuka rule play a decisive role in determining the properties of particles. The widely used $^{3}P_{0}$ model is non-relativistic and contains unknown adjustable parameter $\gamma$ that need to be determined experimentally. Based on the Bethe-Salpeter equation, we have derived a relativistic calculation formula in which the effective strength related to the $^{3}P_{0}$ parameter $\gamma$ is not introduced as an independent fitting parameter, but is consistently determined by the interaction kernel of the Bethe-Salpeter equation. Using this method, we present the total width of $h_{c}(2P)$ and allows a theoretical determination of the parameter $\gamma$ in the $^{3}P_{0}$ model within the present framework.

hep-ph↗

arXiv2025

Constraining modified theories of gravity through the detection of one extremely large mass-ratio inspiral

Extremely large mass-ratio inspirals (XMRIs), formed by brown dwarfs inspiraling into a massive black hole, emit gravitational waves (GWs) that fall within the detection band of future space-borne detectors such as LISA, TianQin, and Taiji. Their detection will measure the astrophysical properties of the MBH in the center of our galaxy (SgrA$^\ast$) with unprecedented accuracy and provide a unique probe of gravity in the strong field regime. Here, we estimate the benefit of using the GWs from XMRIs to constrain the Chern-Simons theory. Our results show that XMRI signals radiated from the late stages of the evolution are particularly sensitive to differences between Chern-Simons theory and general relativity. For low-eccentricity sources, XMRIs can put bounds on the Chern-Simons parameter $\zeta$ at the level of $10^{-1}$ to an accuracy of $10^{-3}$. For high-eccentricity sources, XMRIs can put bounds on the parameter $\zeta$ at the level of $10^{-1}$ to an accuracy of $10^{-6}$. Furthermore, using the time-frequency MCMC method, we obtain the posterior distribution of XMRIs in the Chern-Simons theory. Our results show that almost all the parameters can be recovered within $1\sigma$ confidence interval. For most of the intrinsic parameters, the estimation accuracy reaches $10^{-3}$. For the brown dwarf mass, the estimation accuracy reaches $10^{-1}$, while for $\zeta$, the estimation accuracy reaches $\Delta\log_{10}\zeta=0.08$ for high eccentricity sources and 1.27 for low eccentricity sources.

gr-qc↗

arXiv2025

Probing the light charged Higgs boson, pseudoscalar Higgs boson, and $Z^\prime$ boson in the $U(1)_F$ model at the LHC

In this papar, we study the production and decay of a charged Higgs boson, a pseudoscalar Higgs boson, and a $Z'$ boson at the LHC within the flavor-dependent model (FDM), at the LHC. Considering the constraints from perturbative unitarity and experimental measurements (e.g., the flavor physics data, higgs signal strengths, electroweak precision observables), we investigate the relevant processes by analyzing several common LHC search channels. Motivated by the excess in $t \to b\bar{b}c$ reported by ATLAS, which suggests a charged Higgs boson with a mass near 130 GeV and consistent with B-anomaly expectations, we perform a dedicated simulation for a charged Higgs around this mass. Our results support the experimental hint and predict that this particle has a high discovery potential at the future High-Luminosity Large Hadron Collider (HL-LHC). In contrast, for the pseudoscalar and $Z'$ bosons predicted in our model, they remain beyond the reach of current experiments as well as the expected sensitivity at a 14 TeV collider with an integrated luminosity of 300 fb$^{-1}$.

hep-ph↗