arXiv subjects

Hai-Yang Cheng

Publications and source records attributed to Hai-Yang Cheng.

At least 19 recordsLinked to original sources

arXiv2026

Mixing-angle sensitivity of inclusive $\Xi_{bc} $ and $\Omega_{bc}$ lifetimes

We study the inclusive lifetimes of $\Xi_{bc}^{+}$, $\Xi_{bc}^{0}$, and $\Omega_{bc}^{0}$, with emphasis on the mixing between the spin-zero and spin-one $bc$-diquark configurations. The relevant hadronic matrix elements are evaluated in both the homogeneous bag model (HBM) and the nonrelativistic quark model (NRQM). At the benchmark mixing angles of $-23.0^\circ$ for $\Xi_{bc}$ and $-23.5^\circ$ for $\Omega_{bc}$, the corresponding lifetime triplets are $\left(\tau_{\Xi_{bc}^{+}},\tau_{\Xi_{bc}^{0}},\tau_{\Omega_{bc}^{0}}\right)=\left(0.421^{+0.093}_{-0.093},0.075^{+0.035}_{-0.010},0.223^{+0.074}_{-0.043}\right)\,\mathrm{ps}$ in the HBM and $\left(\tau_{\Xi_{bc}^{+}},\tau_{\Xi_{bc}^{0}},\tau_{\Omega_{bc}^{0}}\right)=\left(0.367^{+0.076}_{-0.070},0.100^{+0.032}_{-0.014},0.229^{+0.066}_{-0.042}\right)\,\mathrm{ps}$ in the NRQM. Relative to the unmixed spin-one reference points, the $\Xi_{bc}^{0}$ and $\Omega_{bc}^{0}$ lifetimes decrease by approximately $17\%$-$19\%$. Neither the minimum nor the maximum of the central lifetime curves occurs at a pure $S_{bc}=0$ or $S_{bc}=1$ configuration; the extrema instead lie at mixed angles with $\left|\phi_{\mathcal{B}}\right|\simeq27^\circ$-$63^\circ$. The two pure-spin limits alone are therefore insufficient to characterize the full mixing-angle dependence.

hep-ph↗

arXiv2026

Topological Diagram Analysis of Charmed Baryon Decays with Vector Mesons

In this work, we further develop the application of the topological diagram approach (TDA) to charmed baryon weak decays $\mathcal{B}_c \to \mathcal{B} V$ with a vector meson in the final state. By incorporating the Korner-Pati-Woo theorem, we show that only five independent sets of TDA parameters are required. Relations among different decay channels arising from isospin, U-spin, and V-spin symmetries are explicitly derived within the TDA framework. Partial wave contributions and form factors associated with different topological diagrams are extracted from global fits to the experimental data. It is found that the form factors $A_2$ and $B_2$ induced from the tensor interaction of the vector mreson with octet baryons are comparable in magnitude to $A_1$ and $B_1$, implying the importance of the tensor coupling in $\mathcal{B}_c \to \mathcal{B} V$ decays. Branching fractions for all $\mathcal{B}_c\to \mathcal{B} V$ channels are predicted, and most measured modes are found to be in good agreement with current data. More physical observables, including up-down asymmetries, longitudinal polarizations as well as observables in the subsequent decays are also predicted. Our results provide a systematic framework for understanding charmed baryon weak decays with vector mesons and can be further tested with future experiments.

hep-ph↗

arXiv2026

Study of doubly heavy baryon lifetimes

We study the lifetimes and inclusive semileptonic decay widths of doubly heavy baryons within the framework of heavy quark expansion. Our analysis includes next-to-leading-order corrections to the dimension-3, -5, and -6 operators, together with the leading dimension-7 contributions, while the nonperturbative matrix elements are evaluated in a bag model with translationally improved baryon wave functions. We obtain $( \tau_{\Xi_{cc}^{++}} , \tau_{\Xi_{cc}^{+}} , \tau_{\Omega_{cc}^{+}} ) = ( 2.67^{+0.95}_{-0.94},\, 0.47^{+0.09}_{-0.08},\, 1.79^{+0.64}_{-0.62} ) \times 10^{-13}\,{\rm s}$ and $( \tau_{\Xi_{bb}^{0}} , \tau_{\Xi_{bb}^{-}} , \tau_{\Omega_{bb}^{-}} ) = ( 0.75^{+0.13}_{-0.11},\, 0.92^{+0.15}_{-0.15},\, 0.93^{+0.15}_{-0.15} ) \times 10^{-12}\,{\rm s}$. The lifetime hierarchy patterns are found to be $\tau(\Xi_{cc}^{++})>\tau(\Omega_{cc}^+)>\tau(\Xi_{cc}^+)$ and $\tau(\Omega_{bb}^{-})\sim\tau(\Xi_{bb}^-)>\tau(\Xi_{bb}^0)$ for doubly charmed and bottom baryons, respectively. The $W$-exchange contribution plays a crucial role in generating the large lifetime splitting in the doubly charmed sector and remains phenomenologically important for doubly bottom baryons. In particular, for $\Xi_{cc}^{+}$ the dominant dimension-6 spectator effect, namely $W$-exchange, surpasses the nominally leading term. The same spectator operator is realized as destructive Pauli interference in $D^+$, owing to the $d$ versus $\bar d$ spectator. Although the $\Xi_{cc}^{+}$ case does not lead to the negative decay width encountered for $D^+$, the absolute value of $\tau(\Xi_{cc}^{+})$ should nevertheless be regarded as only indicative. In addition to the total lifetimes, we calculate the separate nonleptonic and semileptonic contributions, which allow us to trace the pattern of spectator effects in each baryon channel.

hep-ph↗

arXiv2025

CP Violation in Hadronic Weak Decays of Charmed Baryons in the Topological Diagrammatic Approach

CP violation in the charmed baryon sector is generally expected to be very small, of order $10^{-4}$ or even smaller. Nevertheless, large long-distance penguin topologies can be induced through final-state rescattering. At the hadron level, they are manifested as the triangle and bubble diagrams. However, these diagrams consist of not only the penguin but also other tree topologies. Therefore, we focus on the flavor structure of the these diagrams and project out their contributions to penguin and tree topologies. The analysis is performed within the framework of the topological diagram approach and the irreducible SU(3) approach in which the SU(3) flavor symmetry of QCD is realized to describe the nonleptonic decays of charmed baryons. CP violation at the per mille level is found in the following decay modes: $\Lambda_c^+ \to p \pi^0,~\Lambda_c^+ \to p \eta', ~\Xi_c^0 \to \Sigma^0\eta$ and $\Xi_c^+ \to \Sigma^+ \eta$. CP asymmetries in the last three modes receive sizable contributions from the SU(3)-flavor-singlet hairpin diagram.

hep-ph↗

arXiv2025

CP violation studies at Super Tau-Charm Facility

Charge-parity ($C\!P$) violation in the tau-charm energy region is a promising area for sensitive tests of Standard Model (SM) predictions and searches for new, beyond the SM physics. A future Tau-Charm Facility that operates at center-of-mass energies between 2.0 and 7.0 GeV, with a peak luminosity of $0.5\times10^{35}$~cm$^{-2}$s$^{-1}$, would provide huge numbers of hadrons and tau ($τ$) leptons that are produced in low-background environments and with well understood kinematic properties. In this report, prospects for unique studies of $C\!P$ violation in the decay of charmed hadrons, and in the production and decay of hyperons and $τ$ leptons at a next-generation tau-charm facility are discussed. In addition, opportunities for improved tests of $CPT$ invariance test in $K^{0}-\bar{K}^{0}$ mixing are presented.

hep-ex↗

arXiv2025

Charm Physics at the Super $τ$-Charm Factory

The high-luminosity Super $τ$-Charm Factory (STCF) will be a crucial facility for charm-physics research, particularly for the precise measurement of electroweak parameters, measuring $D^0$-$\bar{D}^0$ mixing parameters, investigating Charge-Parity (CP) violation within the charm sector, searching for the rare and forbidden decays of charmed hadrons, and addressing other foundational questions related to charmed hadrons. With the world's largest charm-threshold data, the STCF aims to achieve high sensitivity in studying the strong phase of neutral $D$ mesons using quantum correlation, complementing studies at LHCb and Belle II, and contributing to the understanding of CP violations globally. The STCF will also enable world-leading precision in measuring the leptonic decays of charmed mesons and baryons, providing constraints on the Cabibbo-Kobayashi-Maskawa matrix and strong-force dynamics. Additionally, the STCF will explore charmed hadron spectroscopy. The advanced detector and clean experimental environment of the STCF will enable unprecedented precision, help address key challenges in the Standard Model, and facilitate the search for potential new physics.

hep-ph↗

arXiv2025

Hadronic Weak Decays of Charmed Baryons in the Topological Diagrammatic Approach: An Update

There exist two distinct ways in realizing the approximate SU(3) flavor symmetry of QCD to describe the two-body nonleptonic decays of charmed baryons: the irreducible SU(3) approach (IRA) and the topological diagram approach (TDA). The TDA has the advantage that it is more intuitive, graphic and easier to implement model calculations. We perform a global fit to the currently available data of two-body charmed baryon decays within the framework of the TDA and IRA. The number of the minimum set of tensor invariants in the IRA and the topological amplitudes in the TDA is the same, namely, five in the tree-induced amplitudes and four in the penguin amplitudes. Since we employ the new LHCb measurements to fix the sign ambiguity of the decay parameters $β$ and $γ$, the fit results for the magnitudes of $S$- and $P$-wave amplitudes and their phase shift $δ_P-δ_S$ in both the TDA and IRA are more trustworthy than our previous analyses with uncertainties substantially improved. These results can be tested in the near future. The perspective of having direct {\it CP} violation in the charmed baryon sector at the per mille level is briefly discussed.

hep-ph↗

arXiv2024

Tetraquark nature of the $a_0(980)$ meson in hadronic $D$ decays

The internal structure of the light scalar meson $a_0(980)$ is explored in the three-body $D$ decays of $D\to a_0(980)P\to P_1P_2P$ through the intermediate state $a_0(980)$, where $P$ denotes a pseudoscalar meson. The quasi-two-body $D\to a_0(980)^+P$ decays are governed by the external $W$-emission diagram in which $a_0(980)^+$ is emitted. The predicted branching fractions in the $q\bar q$ model of $a_0(980)$ are too small by one to two orders of magnitude compared to experiment as the amplitude is suppressed by the smallness of the $a_0(980)^+$ decay constant, while those for $D^+\to a_0(980)^0 P$ and $D^0\to a_0(980)^{-}P$ are usually too large. These discrepancies can be resolved provided that $a_0(980)$ is a tetraquark state. In this case, there exist two additional $T$-like topological amplitudes, denoted by $\overline{T}$ and $\tilde T$ which readily account for the discrepancies. An important implication of the tetraquark model is that the $D_s^+\to a_0(980)^+π^0+a_0(980)^0π^+$ decay is not a purely $W$-annihilation process as in the diquark model of $a_0(980)$; it receives dominant contributions from $\overline{T}$ newly noticed in this work. Therefore, measurements of $(D,D_s^+)\to a_0(980)P$ decays lend strong support to the tetraquark picture of $a_0(980)$.

hep-ph↗

arXiv2024

Analysis of Hadronic Weak Decays of Charmed Baryons in the Topological Diagrammatic Approach

We perform a global fit to the experimental data of two-body charmed baryon decays based on the topological diagrammatic approach (TDA) and take into account the phase shifts between $S$- and $P$-wave amplitudes as inspired by the recent BESIII measurement of the decay asymmetry in the decay $Λ_c^+\to Ξ^0K^+$. The TDA has the advantage that it is more intuitive, graphic and easier to implement model calculations. The measured branching fractions and decay asymmetries are well accommodated in the TDA except for a few modes, in particular, the predicted ${\cal B}(Ξ_c^0\to Ξ^-π^+)=(2.83\pm0.10)\%$ is larger than its current value. The equivalence of the TDA and the irreducible SU(3) approach (IRA) is established. We show that the number of the minimum set of tensor invariants in the IRA and the topological amplitudes in the TDA is the same and present their relations. The predicted magnitudes of $S$- and $P$-wave amplitudes and their phase shifts are presented for measured and yet-to-be-measured modes in both the TDA and IRA which can be tested in the near future. Besides the decay $Λ_c^+\to Ξ^0 K^+$, there exist several modes which proceed only through $W$-exchange. In particular, the observed channel $Ξ_c^0\to Σ^+ K^-$ should have phase shifts similar to that in $Λ_c^+\to Ξ^0 K^+$ and its decay asymmetry is predicted to be $-0.21\pm0.17$ which can be used to test our theoretical framework. In contrast, the TDA leads to a large $α$ of order $-0.93$ for the decay $Ξ_c^+\to Ξ^0π^+$ even after the phase-shift effect is incorporated in the fit.

hep-ph↗

arXiv2024

Updated analysis of $D\to PP, V\!P$ and $VV$ decays: Implications for $K_S^0-K_L^0$ asymmetries and $D^0$-$\overline {D}^0$ mixing

An updated analysis of the two-body $D\to PP, V\!P$ and $VV$ decays within the framework of the topological diagram approach is performed. A global fit to the Cabibbo-favored (CF) modes in the $V\!P$ sector gives many solutions with similarly small local minima in $χ^2$. The solution degeneracy is lifted once we use them to predict for the singly Cabibbo-suppressed (SCS) modes. Topological amplitudes are extracted for the $η-η'$ mixing angles $ϕ=40.4^\circ$ and $43.5^\circ$. The $K_S^0-K_L^0$ asymmetries in $D\to K_{S,L}^0M$ decays denoted by $R(D,M)$ are studied. While the predicted $R(D^0,P)$ for $P=π^0, η$ and $η'$ agree with experiment, the calculated $R(D^+,π^+)$, $R(D_s^+, K^+)$, $R(D^0,ω)$ and $R(D^0,ϕ)$ deviate from the data. We conjecture that the relative phase between the topological amplitudes $(C+A)$ and $(T+C)$ should be slightly smaller than $90^\circ$ in order to explain the first two discrepancies and that additional singlet contributions due to the SU(3)-singlet nature of $ω$ and $ϕ$ are needed to account for the last two. For doubly Cabibbo-suppressed (DCS) $D\to V\!P$ decays, their topological amplitudes (double-primed) cannot be all the same as the corresponding ones in the CF modes. The assumption of $E_{V,P}''=E_{V,P}$ for the $W$-exchange amplitude leads to some inconsistencies with the experiment. Through the measured relative phases between CF and DCS channels, the relations of $E_{V,P}''$ with $E_{V,P}$ are determined. Long-distance contributions to the $D^0$-$\overline {D}^0$ mixing parameter $y$ are evaluated in the exclusive approach. In particular, we focus on $D\to PP$ and $V\!P$ decays where $y$ can be reliably estimated. We conclude that $y_{_{P\!P}}\sim (0.110\pm 0.011)\%$ and the lower bound on $y_{_{V\!P}}$ is $(0.220\pm 0.071)\%$.

hep-ph↗

arXiv2024

Topological Diagrams and Hadronic Weak Decays of Charmed Baryons

Inspired by the recent BESIII measurement of the decay asymmetry and the phase shift between $S$- and $P$-wave amplitudes in the decay $Λ_c^+\to Ξ^0K^+$, we perform a global fit to the experimental data of charmed baryon decays based on the topological diagrammatic approach (TDA) which has the advantage that it is more intuitive and easier to implement model calculations. The measured branching fractions and decay asymmetries are well accommodated in TDA except for three modes, in particular, the predicted ${\cal B}(Ξ_c^0\to Ξ^-π^+)=(2.83\pm0.10)\%$ is larger than its current value. The predicted magnitudes of $S$- and $P$-wave amplitudes and their phase shifts are presented for measured and yet-measured modes which can be tested in forthcoming experiments.

hep-ph↗

arXiv2023

Study of singly heavy baryon lifetimes

We study the inclusive decay widths of singly heavy baryons with the improved bag model in which the unwanted center-of-mass motion is removed. Additional insight is gained by comparing the charmed and bottom baryons. We discuss the running of the baryon matrix elements and compare the results with the non-relativistic quark model (NRQM). While the calculated two-quark operator elements are compatible with the literature, those of the four-quark ones deviate largely. In particular, the heavy quark limit holds reasonably well in the bag model for four-quark operator matrix elements but is badly broken in the NRQM. We predict $1-τ(Ω_b)/ τ(Λ_b^0) = (8.34\pm2.22)\%$ in accordance with the current experimental value of $(11.5^{+12.2}_{-11.6})\%$ and compatible with $(13.2\pm 4.7)\%$ obtained in the NRQM. We find an excellent agreement between theory and experiment for the lifetimes of bottom baryons. We confirm that $Ω_c^0$ could live longer than $Λ_c^+$ after the dimension-7 four-quark operators are taken into account. We recommend to measure some semileptonic inclusive branching fractions in the forthcoming experiments to discern different approaches. For example, we obtain ${\cal BF} (Ξ_c^+ \to X e^+ ν_e) = (8.57\pm 0.49)\% $ and ${\cal BF} (Ω_c^0 \to X e^+ ν_e) = (1.88\pm 1.69)\% $ in sharp contrast to ${\cal BF} (Ξ_c^+ \to X e^+ ν_e) = (12.74^{+2.54}_{-2.45})\% $ and ${\cal BF} (Ω_c^0 \to X e^+ ν_e) = (7.59^{+2.49}_{-2.24})\% $ found in the NRQM.

hep-ph↗

arXiv2023

Doubly charmed baryon decays $Ξ_{cc}^{++}\toΞ_c^{(\prime)+}π^+$ in the quark model

In this work we study the doubly charmed baryon decays $Ξ_{cc}^{++}\toΞ_c^{(\prime)+}π^+$ within the framework of the non-relativistic quark model (NRQM). Factorizable amplitudes are expressed in terms of transition form factors, while nonfactorizable amplitudes arising form the inner $W$-emission are evaluated using current algebra and the pole model and expressed in terms of baryonic matrix elements and axial-vector form factors. Nonperturbative parameters are then calculated using the NRQM. They can be expressed in terms of the momentum integrals of baryon wave functions, which are in turn expressed in terms of the harmonic oscillator parameters $α_ρ$ and $α_λ$ for $ρ$- and $λ$-mode excitation. The measured ratio $R$ of the branching fraction of $Ξ_{cc}^{++}\to Ξ^{\prime +}_cπ^+$ relative to $Ξ_{cc}^{++}\to Ξ_c^+π^+$ can be accommodated in the NRQM with $α_{ρ1}$ and $α_{ρ_2}$ being in the vicinity of 0.51 and 0.19, respectively, where $α_{ρ1}$ is the $α_ρ$ parameter for $Ξ_{cc}^{++}$ and $α_{ρ2}$ for $Ξ_{c}^{(\prime)+}$. Decay asymmetries are predicted to be $-0.78$ and $-0.89$ for $Ξ_c^+π^+$ and $Ξ_c^{\prime +}π^+$ modes, respectively, which can be tested in the near future. We compare our results with other works and point out that although some other models can accommodate the ratio $R$, they tend to lead to a branching fraction of $Ξ_{cc}^{++}\to Ξ_c^+π^+$ too large compared to that inferred from the LHCb measurement of its rate relative to $Ξ_{cc}^{++}\toΛ_c^+ K^- π^+π^+$.

hep-ph↗

arXiv2022

CP violation in the interference between $ρ(770)^0$ and $S$-wave in $B^\pm\to π^+ π^-π^\pm$ decays and its implication for CP asymmetry in $B^\pm\to ρ^0π^\pm$

The decay amplitude analyses of $B^\pm\to π^+ π^-π^\pm$ decays in the Dalitz plot performed by LHCb indicate that CP asymmetry for the dominant quasi-two-body decay $B^\pm\toρ(770)^0π^\pm$ was found to be consistent with zero in all three approaches for the $S$-wave component and that CP-violation effects related to the interference between the $ρ(770)^0$ resonance and the $S$-wave were clearly observed. We show that the nearly vanishing CP violation in $B^\pm\toρ^0π^\pm$ is understandable within the framework of QCD factorization. There are two $1/m_b$ power corrections, one from penguin annihilation and the other from hard spectator interactions. They contribute destructively to $A_{CP}(B^\pm\toρ^0π^\pm)$ to render it compatible with zero, in contrast to the sizable negative CP asymmetry predicted in most of the existing models. We next show that the measured interference pattern between the $ρ$ and $S$-wave contributions in the low $m_{π^+π^-}$ region separated by the sign of value of $\cosθ$ with $θ$ being the angle between the two same charged pions measured in the rest frame of the $ρ$ resonance can be explained in terms of the smallness of $A_{CP}(B^+\toρ^0π^+)$ and the interference between $ρ(770)$ and $σ/f_0(500)$. If CP asymmetry in $B^\pm\toρ^0π^\pm$ is not negligible as predicted in many existing models, the observed interference pattern will be destroyed. We conclude that the experimental observation of the interference pattern between $P$- and $S$-waves in the low-$m_{π^+π^-}$ region between 0.5 and 1.0 GeV is consistent with a nearly vanishing CP violation in $B^\pm\toρ^0π^\pm$.

hep-ph↗

arXiv2022

Heavy-Flavor-Conserving Hadronic Weak Decays of Charmed and Bottom Baryons: an Update

This paper serves as an update of the previous work entitled ``Heavy-Flavor-Conserving Hadronic Weak Decays of Charmed and Bottom Baryons". We make an improvement on the bag wave functions by removing the center-of-mass motion of the bag. All the baryon matrix elements are now calculated under the same framework without introducing new parameters. The matrix elements of 4-quark operators are found to be nearly twice larger than the previous ones. The calculated branching fractions of $ Ξ_c ^0 \to Λ_c ^+π^-$ and $Ξ_b^- \to Λ^0_b π^-$ are both in agreement with current experimental results. For the yet-to-be-measured heavy-flavor-conserving decays, we find ${\cal B}( Ξ_c ^+ \to Λ_c ^+π^0) = (13.8 \pm 1.4)\times 10^{-3}$, ${\cal B}( Ξ_b^0 \to Λ^0_b π^0) = (2.6 \pm 0.3)\times 10^{-3}$, ${\cal B}( Ω_c ^0 \to Ξ_c^+π^-) = (2.0 \pm 0.2)\times 10^{-3}$ and ${\cal B}( Ω_c ^0 \to Ξ_c^0π^0)= (1.1 \pm 0.1)\times 10^{-3}$. They are all accessible to LHCb, Belle and Belle II and can be tested in the near future.

hep-ph↗

arXiv2022

Charmed Baryon Physics Circa 2021

This is an update of the two articles (H.Y. Cheng, 2009; Cheng, 2015) in which charmed baryon physics around 2007 and 2015, respectively, were reviewed. In this review we emphasize the experimental progress and the theoretical development since 2015.

hep-ph↗

arXiv2022

Heavy-Flavor-Conserving Hadronic Weak Decays of Charmed and Bottom Baryons

Three decades ago, heavy-flavor-conserving (HFC) weak decays of heavy baryons such as $Ξ_Q\toΛ_Qπ$ and $Ω_Q\toΞ_Qπ$ for $Q=c,b$ had been studied within the framework that incorporates both heavy-quark and chiral symmetries. It was pointed out that if the heavy quark in the HFC process behaves as a spectator, then the $P$-wave amplitude of ${\cal B}_{\bar 3}\to {\cal B}_{\bar 3}+π$ with ${\cal B}_{\bar 3}$ being an antitriplet heavy baryon will vanish in the heavy quark limit. Indeed, this is the case for $Ξ_b\toΛ_b π$ decays. For $Ξ_c\toΛ_cπ$ decays, they receive additional nonspectator contributions arising from the $W$-exchange diagrams through the $cs\to dc$ transition. Spectator and nonspectator $W$-exchange contributions to the $S$-wave amplitude of $Ξ_c\toΛ_cπ$ are destructive, rendering the $S$-wave contribution even smaller. However, the nonspectator effect on the $P$-wave amplitude was overlooked in all the previous model calculations until a very recent investigation within the framework of a constituent quark model in which the parity-conserving pole terms were found to be dominant in $Ξ_c\toΛ_cπ$ decays. Since the pion produced in the HFC process is soft, we apply current algebra to study both $S$- and $P$-wave amplitudes and employ the bag and diquark models to estimate the matrix elements of four-quark operators. We confirm that $Ξ_c\toΛ_cπ$ decays are indeed dominated by the parity-conserving transition induced from nonspectator $W$-exchange and that they receive largest contributions from the intermediate $Σ_c$ pole terms. We also show that the $S$-wave of $Ω_b\to Ξ_b π$ decays vanishes in the heavy quark limit, while $Ω_c\to Ξ_cπ$ receive additional $W$-exchange contributions via $cs\to dc$ transition.

hep-ph↗

arXiv2022

Two- and three-body hadronic decays of charmed mesons involving a tensor meson

We study the quasi-two-body $D\to TP$ decays and the three-body $D$ decays proceeding through intermediate tensor resonances, where $T$ and $P$ denote tensor and pseudoscalar mesons, respectively. We employ $D\to T$ transition form factors based upon light-cone sum rules and the covariant light-front quark model to evaluate the decay rates, with the former giving a better agreement with current data. Though the tree amplitudes with the emitted meson being a tensor meson vanish under factorization approximation, contributions proportional to the tensor decay constant $f_T$ can be produced from vertex and hard spectator-scattering corrections. We also investigate the finite-width effects of the tensor mesons and find that, contrary to three-body $B$ decays, the tensor-mediated $D$ decays are more seriously affected and the narrow width approximation has to be corrected. More experimental data are required in order to extract information topological amplitudes associated with quasi-two-body $D\to TP$ decays. Among the data, the $D^+\to f_2π^+$ and $D^+\to \bar K_2^{*0}π^+$ branching fractions are not self consistent and further clarification is called for.

hep-ph↗