arXiv subjects

Hua-Yu Jiang

Publications and source records attributed to Hua-Yu Jiang.

13 recordsLinked to original sources

arXiv2026

Semileptonic Decay of $Λ_b \rightarrow N(1520)\ell^-\barν_{\ell}$ from QCD Light-cone Sum Rules

We investigate the complete set of vector and axial-vector form factors for the charged-current transition $Λ_b^0\to N(1520)^+$ using QCD light-cone sum rules (LCSRs) based on the light-cone distribution amplitudes (LCDAs) of the $Λ_b$ baryon, with the hard-scattering kernels evaluated at tree level. In the hadronic representation of the correlation function, we include the pole contributions of both the negative-parity $N(1520)$, with $J^P=3/2^-$, and the positive-parity $N(1720)$, with $J^P=3/2^+$. By matching a selected set of Lorentz structures, we derive sum rules that separate the $N(1520)$ contribution from the $N(1720)$ contribution within the adopted two-pole hadronic ansatz. After extrapolating the large-recoil LCSR results over the physical $q^2$ region using a pole-improved $z$ expansion truncated at linear order, we predict the differential branching fractions, the lepton forward-backward asymmetry, the charged-lepton polarization, and the $N(1520)$ polarization in $Λ_b^0\to N(1520)^+\ell^-\barν_{\ell}$ ($\ell=e,μ,τ$). The corresponding total branching fractions are $\mathcal{B}_{e,μ,τ} =(12.4\pm10.5,\,12.4\pm10.5,\,5.0\pm4.3)\times10^{-5}$. Within the stated approximations, these results may serve as theoretical benchmarks for future experimental studies of this channel.

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arXiv2026

Finite-$t$ and target mass corrections for the short-distance expansion of quasi(pseudo) GPDs

We calculate the ``kinematic'' corrections $t/P_z^2$ and $m_N^2/P_z^2$ to the short distance expansion of gauge-invariant nonlocal quark-antiquark operators sandwiched between nucleon states with different momenta. Here $t$ is the momentum transfer, $m_N$ is the nucleon mass and $P_z$ is the momentum component in the direction of the quark-antiquark separation, which is assumed to be large. These matrix elements can be calculated in lattice QCD and, at leading twist, expressed in terms of moments of the generalized parton distrubutions (GPDs). Our results allow one to control one of principal uncertainties in such calculations and extend their region of applicability to larger momentum transfers, which is important in the quest to access the three-dimension image of the proton. The calculated corrections turn out to be significant for a realistic lattice QCD setup.

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arXiv2024

Transition form factors of the $Λ_b \rightarrow Λ(1520)$ in QCD light-cone sum rules

In this work, we investigate the transition form factors for $Λ_b\rightarrow{Λ(1520)}$ within the framework of light-cone sum rules (LCSR), using the light-cone distribution amplitudes (LCDAs) of the $Λ_b$-baryon. In the hadronic representation of the correlation function, we carefully select the appropriate Lorentz structures and isolate the contributions from both the $Λ(1520)(J^P=(3/2)^-)$ and the $Λ(1890)(J^P=(3/2)^+)$, ensuring that the form factors for $Λ_b\rightarrow{Λ(1520)}$ can be calculated unambiguously. We also provide predictions for various physical observables in the decay $Λ_b\rightarrow{Λ(1520)}l^+l^-$, including the differential branching fraction, the lepton-side forward-backward asymmetry, the longitudinal polarization fraction, and the CP-averaged normalized angular observable. Our prediction for the differential branching fraction of $Λ_b\rightarrow{Λ(1520)}μ^+μ^-$ is in good agreement with the LHCb measurement within the uncertainties.

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arXiv2024

Final-state rescattering mechanism of charmed baryon decays

The dynamical studies on the non-leptonic weak decays of charmed baryons are always challenging, due to the large non-perturbative contributions at the charm scale. In this work, we develop the final-state rescattering mechanism to study the two-body non-leptonic decays of charmed baryons. The final-state interaction is a physical picture of long-distance effects. Instead of using the Cutkosky rule to calculate the hadronic triangle diagrams which can only provide the imaginary part of decay amplitudes, we point out that the loop integral is more appropriate, as both the real parts and the imaginary parts of amplitudes can be calculated completely. In this way, it can be obtained for the non-trivial strong phases which are essential to calculate CP violations. With the physical picture of long-distance effects and the reasonable method of calculations, it is amazingly achieved that all the nine existing experimental data of branching fractions for the $Λ_c^+$ decays into an octet light baryon and a vector meson can be explained by only one parameter of the model. Besides, the decay asymmetries and CP violations are not sensitive to the model parameter, since the dependence on the parameter is mainly cancelled in the ratios, so that the theoretical uncertainties on these observables are lowered down.

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arXiv2024

The two-loop coefficient functions for double deeply virtual Compton scattering

Making use of conformal symmetry of large-$n_f$ QCD in $d=4-2ε$ dimensions at the Wilson-Fischer fixed point, we calculate the two-loop coefficient functions in the operator product expansion of two electromagnetic currents in general kinematics with two different photon virtualities. This result is necessary for the description of the double deeply virtual Compton scattering to the next-to-next-to-leading order accuracy, but is also interesting for a range of other two-photon processes. We present analytic expression for the coefficient function in momentum fraction space in the $\overline{\text{MS}}$ scheme and study its numerical impact on the Compton form factors for a simple model of the generalized parton distributions. The calculated corrections turn out to be large and are significant for the kinematics of proposed experiments.

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arXiv2024

An improved calculation of the $D_{(s)}^D_{(s)}V$ and $B_{(s)}^B_{(s)}V$ couplings from light-cone sum rules

We present an improved calculation of the $D_{(s)}^*D_{(s)}V$ and $B_{(s)}^*B_{(s)}V$ coupling constants, where $V$ denotes $ρ$, $K^\ast$, $ω$, and $ϕ$ meson. These couplings govern the QCD long-distance dynamics in interactions between heavy pseudoscalar/vector mesons and light vector mesons. Our analysis is conducted within the framework of QCD light-cone sum rules (LCSRs) by utilizing the light-cone distribution amplitudes (LCDAs) of light vector mesons. By systematically incorporating the subleading power corrections and higher-twist contributions at leading order (LO) and including the next-to-leading order (NLO) corrections at leading power, we achieve enhanced accuracy in the light-cone operator product expansion (OPE) for the underlying correlation function. In assessing the reliability of the established LCSRs, we consider uncertainties arising from the choice of the quark-hadron duality region in the double dispersion relation. Building upon these improvements, we accomplish an optimized computation and analysis for the strong coupling constants $g_{H^\ast HV}$ which are used to extract the effective coupling $λ$ in the heavy meson chiral perturbation theory (HM$χ$PT). Furthermore, we investigate the $SU(3)$ flavour symmetry breaking effects in detail and compare our sum rule calculations with previous studies in an exploratory way.

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arXiv2024

Precision calculations of the $D_{(s)}D_{(s)}V$ and $B_{(s)}B_{(s)}V$ couplings from light-cone sum rules

We present an improved calculation of the $HHV$ ($H=D_{(s)},\, B_{(s)}$, $V= ρ$, $K^\ast$, $ω$, and $ϕ$) coupling constants $g_{HHV}$ beyond leading order in $α_s$ from QCD light-cone sum rules (LCSRs) by means of the light-cone distribution amplitudes (LCDAs) of light vector mesons. Near the light-cone, the next-to-leading order QCD corrections for the vacuum-to-vector-meson correlation function are included at leading power in $δ_V = m_V/m_Q$ ($Q=b,c$) within the framework of hard-collinear factorization. The higher-twist corrections from two-particle and three-particle vector meson LCDAs are systematically incorporated at leading order in $α_s$ by applying the method of background field in LCSRs. Based on these improvements, we perform a systematic computation of the strong coupling constants $g_{H HV}$ and extract the effective coupling $β$ of the heavy meson chiral perturbation theory (HM$χ$PT). Furthermore, we accomplish the analysis for the relation between the coupling $g_{HHV}$ and the residue of the $H\to V$ transition form factor $A_0$ at heavy pseudoscalar pole. Additionally, we provide a detailed investigation of the $SU(3)$ flavour symmetry breaking effects and conduct a comparative analysis with results from previous studies.

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arXiv2021

Weak decays of bottom-charm baryons: $\mathcal{B}_{bc}\to\mathcal{B}_bP$

After the discovery of the double-charm baryon $Ξ_{cc}^{++}$ by LHCb, one of the most important topics is to search for the bottom-charm baryons which contain a $b$ quark, a $c$ quark and a light quark. In this work, we study the two-body non-leptonic weak decays of a bottom-charm baryon into a spin-$1/2$ bottomed baryon and a light pseudoscalar meson with the short-distance contributions calculated under the factorization hypothesis and the long-distance contributions considering the final-state-interaction effects. The branching fractions of all fifty-seven decay channels are estimated. The results indicate that $Ξ_{bc}^+\toΞ_b^0π^+$, $Ξ_{bc}^{0}\toΞ_{b}^{-}π^+$ and $Ω_{bc}^0\toΩ_b^-π^+$ decay modes have relatively large decay rates and thus could be used to experimentally search for the bottom-charm baryons. The topological diagrams and the SU(3) symmetry of bottom-charm baryon decays are discussed.

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arXiv2021

Rescattering mechanism of weak decays of double-charm baryons

The doubly charmed baryon $Ξ_{cc}^{++}$ was recently observed by LHCb via the decay processes of $Ξ_{cc}^{++}\to Λ_c^+ K^-π^+π^+$ and $Ξ_c^+π^+$. These discovery channels were successfully predicted in the framework that the short-distance contributions are calculated under the factorization hypothesis and the long-distance contributions are estimated using the rescattering mechanism for the final-state-interaction effects. In this paper, we illustrate the above framework in details by systematic studies on the two-body baryonic decays $\mathcal{B}_{cc}\to\mathcal{B}_{c}P$ involving the doubly charmed baryons $\mathcal{B}_{cc}=(Ξ_{cc}^{++} , Ξ_{cc}^+,Ω_{cc}^+)$, the singly charmed baryons $\mathcal{B}_{c}=(\mathcal{B}_{\bar{3}}, \mathcal{B}_{6})$ and the light pseudoscalar mesons $P=(π,K,η_{1,8})$.

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arXiv2018

$D^0$-$\overline{D}^0$ mixing parameter $y$ in the factorization-assisted topological-amplitude approach

We calculate the $D^0$-$\overline{D}^0$ mixing parameter $y$ in the factorization-assisted topological-amplitude (FAT) approach, considering contributions from $D^{0}\to PP$, $PV$, and $VV$ modes, where $P$ ($V$) stands for a pseudoscalar (vector) meson. The $D^{0}\to PP$ and $PV$ decay amplitudes are extracted in the FAT approach, and the $D^{0}\to VV$ decay amplitudes with final states in the longitudinal polarization are estimated via the parameter set for $D^{0}\to PV$. It is found that the $VV$ contribution to $y$, being of order of $10^{-4}$, is negligible, and that the $PP$ and $PV$ contributions amount only up to $y_{PP+PV}=(0.21\pm0.07)\%$, a prediction more precise than those previously obtained in the literature, and much lower than the experimental data $y_{\rm exp}=(0.61\pm0.08)\%$. We conclude that $D^{0}$ meson decays into other two-body and multi-particle final states are relevant to the evaluation of $y$, so it is difficult to understand it fully in an exclusive approach.

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arXiv2018

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, $Ξ_{cc}^{++}$ and $Ξ_{cc}^{+}$, 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 $Ξ_{cc}^{++}\to Λ_c^+K^-π^+π^+$ and $Ξ_c^+π^+$ as the first priority for experiments to search for the doubly heavy baryons.

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arXiv2018

Fragmentation-fraction ratio $f_{Ξ_b}/f_{Λ_b}$ in $b$- and $c$-baryon decays

We study the ratio of fragmentation fractions, $f_{Ξ_b}/f_{Λ_b}$, from the measurement of $Ξ_b^0\to Ξ_c^+π^-$ and $Λ_b^0\to Λ_c^+π^-$ with $Ξ_{c}^{+}/Λ_{c}^{+}\to p K^-π^+$. With the branching fraction $\mathcal{B}(Ξ_c^+\to pK^-π^+)=(2.2\pm0.8)\%$ obtained under the U-spin symmetry, the fragmentation ratio is determined as $f_{Ξ_b}/f_{Λ_b}$=$0.054\pm0.020$. To reduce the above uncertainties, we suggest to measure the branching fractions of $Ξ_c^+\to p \overline K^{*0}$ and $Λ_c^+\to Σ^+ K^{*0}$ at BESIII, Belle(II) and LHCb.

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arXiv2017

$K_{S}^{0}-K_{L}^{0}$ asymmetries in $D$-meson decays

The $K_{S}^{0}-K_{L}^{0}$ asymmetries in the $D$ meson decays, induced by the interference between the Cabibbo-favored and the doubly Cabibbo-suppressed amplitudes, can help to understand the dynamics of charm decays. All possible processes of two-body non-leptonic $D$ decays into one neutral kaon and another pseudoscalar or vector meson are considered. We study the $K_{S}^{0}-K_{L}^{0}$ asymmetries and the branching fractions of corresponding processes in the factorization-assisted topological-amplitude approach in which significant flavor $SU(3)$ symmetry breaking effects are included. The branching fractions of $K_{L}^{0}$ modes are predicted. It is first found that the $K_{S}^{0}-K_{L}^{0}$ asymmetries in the $D^0$-meson decays are shifted by the $D^0-\overline D^0$ mixing parameter $y_{D}\simeq0.006$, to be $0.113\pm0.001$ for all the relevant $D^{0}$ decay modes. Our results on $K_{S}^{0}-K_{L}^{0}$ asymmetries are consistent with the current data and could be tested by experiments in the future.

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