arXiv subjects

Run-Hui Li

Publications and source records attributed to Run-Hui Li.

At least 19 recordsLinked to original sources

arXiv2026

Final-state rescattering in $\bar{B}^{0}_{(s)}\to \Lambda^{+}_{c}\bar{\Lambda}^{-}_{c}$ decays

The LHCb Collaboration has recently reported the first observation of the decay $\bar B_s^0\to \Lambda_c^+\bar\Lambda_c^-$, along with measurements of the branching fractions for both $\bar B^0\to \Lambda_c^+\bar\Lambda_c^-$ and $\bar B_s^0\to \Lambda_c^+\bar\Lambda_c^-$. In this work, we investigate these two decays within the framework of final state re-scattering. Our results show that the predicted branching fractions are consistent with the experimental measurements, indicating the significant role of long-distance final-state interactions in such baryonic B decays. Furthermore, we present predictions for the direct CP asymmetries and the asymmetry parameters. Numerically, both decays exhibit nearly vanishing CP asymmetries, while $\bar B^0\to \Lambda_c^+\bar\Lambda_c^-$ displays a sizable longitudinal polarization, providing a sensitive observable for testing our theoretical framework in future experimental measurements.

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arXiv2026

Precise theoretical prediction on branching fractions and polarizations of $D \to V V$ decays

We present a precise and systematic analysis of $D \to V V$ decays within the factorization-assisted topological-amplitude approach, where $D$ denotes the set $\{D^0, \, D^+,\, D^+_s\}$ and $V$ represents the vector mesons $\rho, K^*, \omega$, and $\phi$. Given the limited current experimental data, the factorization-assisted topological-amplitude approach serves as a available phenomenological framework for predicting charmed meson decays to both vector mesons. In this framework, incorporating flavor SU(3) symmetry breaking effects, we can express nonfactorizable contributions of different modes as a minimal set of universal parameters globally fitted to experimental data. Utilizing 36 experimental data points for $D \to VV$ decays, we precisely extract ten nonfactorizable parameters associated with the $C$ and $E$ topological diagrams with $\chi^2/\mathrm{d.o.f.}=8.43$. We find that a large strong phase in the longitude $E$ amplitude cause strong destructive interference with the $C$ longitudinal component, yielding $f_\parallel >f_L $, contrary to the naive factorization predictions. Additionally, for modes processing exclusively by the $E$ diagram, the amplitude hierarchy $|S|<|D|$ leads to a $D$-wave branching fraction larger than that of the $S$-wave. This explains recent observations that contradict $S$-wave dominance predictions. The predicted branching fractions and polarizations for 28 decay modes are consistent with existing experimental data. Unobserved modes, especially those with branching fractions of order $10^{-3}\sim10^{-2}$, the $D$-wave dominated modes, and modes exhibiting $f_\parallel >f_L $, await measurement by BESIII, STCF, Belle II, and LHCb.

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arXiv2026

Probing direct $CP$ violation in $\Lambda_b^0 \to P_c^+ h^-$ $(h=\pi,K)$ with final-state rescattering

The LHCb Collaboration recently reported a measurement of the difference in direct CP asymmetries for the decays $\Lambda_b^0 \to J/\psi \, p \, h^-$ (with $h = K, \pi$), offering new experimental constraints on the decay dynamics of heavy baryons into charmonium final states. Inspired by these findings, we explore the branching ratios and direct CP violations for the decays $\Lambda_b^0 \to P_c^+(4312, 4440, 4457)\,h^-$ within the framework of final-state rescattering. Our analysis indicates that the branching fractions for $\Lambda_b^0 \to P_c^+ \pi^-$ lie around the $10^{-6}$ level, with the corresponding direct CP asymmetries approaching approximately $1\%$. In contrast, the direct CP violation for the decay $\Lambda_b^0 \to P_c^+ K^-$ is found to be very small, while its branching ratios show a strong dependence on the spin assignments of the $P_c$ states. These predictions may provide useful guidance for more precise CP measurements and amplitude analyses in the $P_c$ region in future experiments.

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arXiv2025

Analysis of three-body charmed $B$ meson decays $B \to {D}(V^* \to){V P}$

We systematically analyze the decays $B_{(s)} \to D_{(s)} (V^* \to)\, V\, P$, where $V^*$ represents a vector resonance ($\rho, \, \omega$ or $K^*$), and $V P$ denotes the final-state meson pairs $ \omega\, \pi$, $ \rho\, \pi$ and $ \rho \, K$. The intermediate subprocesses $B_{(s)} \to D_{(s)} V^*$ are calculated in the factorization-assisted topological-amplitude approach, while the intermediate resonant states $V^*$ are modeled using a relativistic Breit-Wigner distribution, subsequently decaying into $VP$ through strong interactions. We predict the off-shell effects of the ground-state resonances ($\rho,\, \omega, \, K^*$) in $B_{(s)} \to D_{(s)} (V^* \to )V P$. Our results show that the virtual contributions from $\rho \to \omega \, \pi$, $\omega \to \rho\, \pi$, and $K^* \to \rho\, K$ are crucial for these three-body decays, $B_{(s)} \to D_{(s)} V\, P$. In particular, the branching fractions arising from the $\rho$ and $\omega$ virtual effects can be comparable to the total decay rates of $B_{(s)} \to D_{(s)} \omega\, \pi$ and $B_{(s)} \to D_{(s)} \rho\, \pi$, respectively. Decays with branching fractions of order $10^{-6}-10^{-4}$ are expected to be measurable at Belle II and LHCb. Compared with previous perturbative QCD predictions for $B_{(s)} \to D_{(s)} (\rho \to)\, \omega\, \pi$, our results are consistent but exhibit higher precision.

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arXiv2025

Semileptonic and nonleptonic $\bar{B}_{s}\to D_{sJ}$ decays in covariant light-front approach

In this work, we investigate the $\bar{B}_{s}\to D_{sJ}$ transitions in covariant light-front approach, where $D_{sJ}$ denotes an s-wave or p-wave $c\bar{s}$ meson state. We first obtain the transition form factors within the framework of the quark model, and then apply the obtained form factors to obtain the branching fractions of semileptonic and nonleptonic decays. We also compare our results with experimental data and other theoretical predictions. We find that some branching fractions are sizable and might be accessible at the LHC and future $e^{+}$-$e^{-}$ colliders. Our work is expected to be of great value for establishing corresponding decay channels, and also be helpful in understanding the non-perturbative QCD dynamics.

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arXiv2024

Final-state rescattering mechanism in bottom-baryon decays

The first observation of $CP$ violation in baryon decays was recently reported by the LHCb collaboration in $\Lambda_b^0\to pK^-\pi^+\pi^-$ with $A_{CP} = (2.45 \pm 0.46 \pm 0.10)\%$, which inspires the study on baryon non-leptonic decays. In this work, we perform the first calculation of five exclusive non-leptonic decays, $\Lambda^{0}_{b}\to p\pi^{-}, p K^{-},p\rho^{-},pK^{*-}$ and $\Lambda\phi$, within the re-scattering approach. The triangle diagrams at hadron level are calculated in form of loop integrations. It leads to the generation of strong phases, which is essential to the calculation of $CP$ asymmetries. We present numerical results for branching ratios, direct and partial-wave $CP$ asymmetries, decay asymmetry parameters and their associated $CP$ asymmetries. Our results are consistent with the current LHCb experimental data, which indicates the validity and potential of our approach in studying the $CP$ asymmetries of $b$-baryon decays. Most of our results are expected to be tested in future experiments.

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arXiv2024

A progress in inverse matrix method in QCD sum rules

In traditional QCD sum rules, the simple hadron spectral density model of ``delta-function-type ground state + theta-function-type continuous spectrum" determines that there is no perfect parameter selection. In recent years, inverse problem methods, especially the inverse matrix method, have shown better handling of QCD sum rules. This work continues to develop the inverse matrix method. Considering that the narrow-width approximation may still be a good approximation, we separate the contribution of the ground state from the spectral density. Then follow the general steps of the inverse matrix method to extract physical quantities such as decay constants that we are sometimes more interested in.

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arXiv2024

Analysis of three-body decays $B \to D (V \to ) PP $ under the factorization-assisted topological-amplitude approach

Motived by the accumulated experimental results on three-body charmed $B$ decays with resonance contributions in Babar, LHCb and Belle (II), we systematically analyze $B_{(s)} \to D_{(s)} (V \to) P_1 P_2 $ decays with $V$ representing a vector resonance ($\rho, K^*, \omega$ or $\phi$) and $P_{1,2}$ as a light pseudoscalar meson (pion or kaon). The intermediate subprocesses $B_{(s)} \to D_{(s)} V$ are calculated with the factorization-assisted topological-amplitude (FAT) approach and the intermediate resonant states $V$ described by the relativistic Breit-Wigner distribution successively decay to $P_1 P_2$ via strong interaction. Taking all lowest resonance states ($\rho, K^*, \omega, \phi$) into account, we calculate the branching fractions of these decay modes as well as the Breit-Wigner-tail effects for $B_{(s)} \to D_{(s)} (\rho ,\omega \to) KK$. Our results agree with the data by Babar, LHCb and Belle (II). Among the predictions that are still not observed, there are some branching ratios of order $10^{-6}-10^{-4}$ which are hopeful to be measured by LHCb and Belle II. Our approach and the perturbative QCD approach (PQCD) adopt the compatible theme to deal with the resonance contributions. What's more, our data for the intermediate two-body charmed $B$-meson decays in FAT approach are more precise. As a result, our results for branching fractions have smaller uncertainties, especially for color-suppressed emission diagram dominated modes.

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arXiv2023

Analysis of three-body charmless $B$-meson decays under the factorization-assisted topological-amplitude approach

We analyze quasi-two-body charmless $B$ decays $B_{(s)} \to P_1 V \to P_1 P_2 P_3$ with $V$ representing a vector resonant, and $P_{1,2,3}$ as a light pseudo-scalar meson, pion, kaon or $\eta^{(\prime)}$. The intermediate processes $B_{(s)} \to P_1 V $ are calculated in the factorization-assisted topological-amplitude approach and the vector resonant effects are described by the Breit-Wigner propagator, which successively decay to $P_1 P_2$ via strong interaction. Taking into account of all vector resonances in ground state, $\rho, K^*, \omega, \phi$, we present the related branching fractions, and calculate the virtual effects for $B_{(s)} \to \pi, K (\rho ,\omega \to) KK$. We also predict direct $\it{CP}$ asymmetries of three body B decay modes with $\rho, K^*$ resonances as intermediate states. Our predicted branching fractions of decay modes dominated by the color-favored tree diagram or the color-favored penguin diagram are consistent with the perturbative QCD approach's predictions as well as QCD factorization approach. While for those nonperturbative contribution dominated decay modes, the branching ratios in this work are in better agreement with current experimental data than the PQCD predictions and the QCD factorization results due to their shortage of the nonperturbative contributions or $1/m_b$ power corrections. Many of the decays channels, especially for direct $\it{CP}$ asymmetries, are waiting for the future experiments.

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arXiv2021

Analysis of three-body charmed B meson decays under the factorization-assisted topological-amplitude approach

We analyze the quasi-two-body charmed $B$ decays $B^{+,0}_{(s)} \to D_{(s)}^* P_2 \to D_{(s)} P_1 P_2$ with $P_{1,2}$ as a pion or kaon. The intermediate processes $B_{(s)} \to D_{(s)}^* P_2 $ are calculated with the factorization-assisted topological-amplitude approach and the resonant effects are calculated with the Breit-Wigner formalism. Taking all p-wave resonance states $ \bar D_{(s)}^*$ into consideration, we present the related branching fractions, calculate the Breit-Wigner-Tail effects, and investigate the flavor $SU(3)$ breaking effects. Most of our branching fractions are consistent with the perturbative QCD approach's predictions as well as the current experimental data. With more precision calculation of the intermediate two body charmed B meson decays, our quasi-two-body B decays calculation has significantly less theoretical uncertainty than the perturbative QCD approach. Many of those channels without any experimental data will be confronted with the future more accurate experiment measurements. Our results of the Breit-Wigner-tail effects also agree with the experimental very well. In $B^0$ decays this effect can reach approximately to $5\%$. It is also found that the Breit-Wigner-tail effects are not sensitive to the widths of their corresponding resonances. The flavor $SU(3)$ symmetry breaking effect is also investigated.

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arXiv2020

Weak Decays of Doubly Heavy Baryons: ${\cal B}_{cc}\to {\cal B} D^{(*)}$

The discovery of $\Xi_{cc}^{++}$ has inspired new interest in studying doubly heavy baryons. In this study, the weak decays of a doubly charmed baryon ${\cal B}_{cc}$ to a light baryon ${\cal B}$ and a charm meson $D^{(*)}$ (either a pseudoscalar or a vector one) are calculated. Following our previous work, we calculate the short distance contributions under the factorization hypothesis, whereas the long distance contributions are modeled as the final state interactions which are calculated with the one particle exchange model. We find that the ${\cal B}_{cc}\to {\cal B} D^{*}$ decays' branching ratios are obviously larger, as they receive contributions of more polarization states. Among the decays that we investigate, the following have the largest branching fractions: ${\cal BR}(\Xi_{cc}^{++}\rightarrow\Sigma^{+}D^{*+}) \in [0.46\%, 3.33\%]$ estimated with $\tau_{\Xi_{cc}^{++}}=256$ fs; ${\cal BR}(\Xi_{cc}^{+}\rightarrow\Lambda D^{*+}) \in [0.38\%, 2.63\%]$ and ${\cal BR}(\Xi_{cc}^{+}\rightarrow\Sigma^{0} D^{*+}) \in [0.45\%, 3.16\%]$ with $\tau_{\Xi_{cc}^+}=45$ fs; and ${\cal BR}(\Omega_{cc}^{+}\rightarrow\Xi^{0} D^{*+}) \in [0.27\%, 1.03\%]$, ${\cal BR}(\Omega_{cc}^{+}\rightarrow\Xi^{0} D^{+}) \in [0.07\%, 0.44\%]$ and ${\cal BR}(\Omega_{cc}^{+}\rightarrow\Sigma^{0} D^{*+}) \in [0.06\%, 0.45\%]$ with $\tau_{\Omega_{cc}^+}=75$ fs. By comparing the decay widths of pure color commensurate channels with those of pure bow-tie ones, we find that the bow-tie mechanism plays an important role in charm decays.

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arXiv2020

The semi-leptonic form factors of $\Lambda_{b}\to\Lambda_{c}$ and $\Xi_{b}\to\Xi_{c}$ in QCD sum rules

In this work, the full leading order results of the form factors for $\Xi_{b}\to\Xi_{c}$ and $\Lambda_{b}\to\Lambda_{c}$ are obtained in QCD sum rules. Contributions from up to dim-5 have been considered. For completeness, we also study the two-point correlation function to obtain the pole residues of $\Xi_{Q}$ and $\Lambda_{Q}$, and higher accuracy is achieved. For the three-point correlation function, since stable Borel regions can not be found, about $20\%$ uncertainties are introduced for the form factors of $\Xi_{b}\to\Xi_{c}$ and $\Lambda_{b}\to\Lambda_{c}$. Our results for the form factors are consistent with those of the Lattice QCD within errors.

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arXiv2020

The SVZ sum rules and the heavy quark limit for $\Lambda_{Q}$

In this work, we evaluate the accuracy of the leading order results in Shifman-Vainshtein-Zakharov (SVZ) sum rules and the leading power results in the heavy quark limit for the mass of $\Lambda_{Q}$. Up to dim-5 condensate contributions are considered. By comparing with the experimental results, we find that the leading order results in SVZ sum rules can reach about 5\% accuracy both for $\Lambda_{b}$ and $\Lambda_{c}$, and it seems that better results can be obtained from the sum rules of the heavy quark limit both for $\Lambda_{b}$ and $\Lambda_{c}$. We re-check that the SVZ sum rules in the heavy quark limit coincide with the HQET sum rules. As a byproduct, we also have an exploratory discussion on the $ud$ diquark in $\Lambda_{Q}$.

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arXiv2020

A comprehensive analysis of weak transition form factors for doubly heavy baryons in the light front approach

The transition form factors for doubly heavy baryons into a spin-$1/2$ or spin-$3/2$ ground-state baryon induced by both the charged current and the flavor changing neutral current are systematically studied within the light-front quark model. In the transition the two spectator quarks have two spin configurations and both are considered in this calculation. We use an updated vertex functions, and inspired by the flavor SU(3) symmetry, we also provide a new approach to derive the flavor-spin factors. With the obtained transition form factors, we perform a phenomenological study of the corresponding semi-leptonic decays of doubly heavy baryons induced by the $c\to d/s \ell^+\nu$, $b\to c/u\ell^-\bar \nu$ and $b\to d/s\ell^+\ell^-$. Results for partial decay widths, branching ratios and the polarization ratios $\Gamma_{L}/\Gamma_{T}$s are given. We find that most branching ratios for the semi-leptonic decays induced by the $c\to d,s$ transitions are at the order of $10^{-3}\sim10^{-2}$, which might be useful for the search of other doubly-heavy baryons. Uncertainties in form factors, the flavor SU(3) symmetry and sources of symmetry breaking effects are discussed. We find that the SU(3) symmetry breaking effects could be sizable in charmed baryon decays while in the bottomed case, the SU(3) symmetry breaking effects are less significant. Our results can be examined at the experimental facilities in the future.

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arXiv2018

Weak Decays of Doubly Heavy Baryons: ${\cal B}_{cc}\to {\cal B}_c V$

The weak decays of a spin-$1/2$ doubly charm baryon (${\cal B}_{cc}$) to a spin-$1/2$ singly charm baryon (${\cal B}_c$) and a light vector meson ($V$) are studied under a phenomenological scheme. The contributions are classified into different topological diagrams, among which the short distance ones are calculated under the factorization hypothesis, and the long distance contributions are modelled as final-state interactions (FSIs) which are estimated with the one-particle-exchange model. In calculation the topological contributions tend to fall in a hierarchy. The branching fractions or decay widths are estimated, and it indicates that $\Xi_{cc}^+\to\Xi_c^+\pi^+\pi^-$ and $\Omega_{cc}^{+}\rightarrow\Xi_{c}^{+}K^-\pi^+$ can be used as candidate decays for searching $\Xi_{cc}^+$ and $\Omega_{cc}^+$. Some decays that are mainly activated by the long distance effects are found, observation on which in future experiments can help to understand the role of FSIs in charm baryon decays.

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arXiv2018

Exclusive production of $B_c$ mesons in $e^+e^-$ colliders

Within the framework of the perturbative QCD approach, we calculate the time-like $B_cB_c(B_c^*)$ form factors $F(Q^2)$ and $A_2(Q^2)$. We include relativistic corrections and QCD corrections, either of which can give about $20\%$ correction to the leading-order contribution, but there are cancellation effects between them. We calculate the cross sections of the $e^+e^-\to B_c^-B_c^+(B_c^{*+})$ processes. The cross sections are enhanced at the $Z$ pole to be $\sigma^{PP}(Q=m_Z) \sim 1.3\times10^{-5}\text{pb}$ and $\sigma^{PV}(Q=m_Z) \sim 2.5\times10^{-5}\text{pb}$, which are still too small to be detected by proposed $e^+e^-$ colliders such as the Circular Electron Positron Collider.

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arXiv2018

Search for doubly heavy baryon via weak decays

Using the factorization approach and taking into account the final state interaction, we calculate the two body non-leptonic decays of doubly heavy baryons. After comparing the semi-leptonic decays and all possible hadronic decay channels, we found some channels with large branching ratios. Taking the detection efficiency into consideration, we suggest $\Xi_{cc}^{++}$ as the first search goal and $\Xi_{cc}^{++}\to \Lambda_c^+K^-\pi^+\pi^+$ and $\Xi_{cc}^{++}\to\Xi_{c}^{+}\pi^{+}$ as the golden discovery channels with $\Lambda_c^+$ reconstructed by $pK^-\pi^+$ and $\Xi_{c}^+ \to p K^- \pi^+$, respectively.

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arXiv2017

Discovery Potentials of Doubly Charmed Baryons

The existence of doubly heavy flavor baryons has not been well established experimentally so far. In this Letter we systematically investigate the weak decays of the doubly charmed baryons, $\Xi_{cc}^{++}$ and $\Xi_{cc}^{+}$, which would be helpful for experimental searches for these particles. The branching fractions are studied under the factorization hypothesis for the short-distance contributions and considering the rescattering effect for the long-distance contributions which are significantly enhanced. Comparing all the decay modes, we recommend the processes of $\Xi_{cc}^{++}\to \Lambda_c^+K^-\pi^+\pi^+$ and $\Xi_c^+\pi^+$ as the first priority for experiments to search for the doubly heavy baryons.

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