arXiv subjects

Chu-Wen Xiao

Publications and source records attributed to Chu-Wen Xiao.

At least 19 recordsLinked to original sources

arXiv2026

In search for signals of the $D\bar{D}$ bound state $X(3700)$ from study of the $B^+ \to D^+ D^- K^+$, $B^0 \to D^+ D^- K^0$ and $Λ_b \to D^+ D^- Λ$ reactions

We perform a theoretical study of the $B^+ \to D^+ D^- K^+$, $B^0 \to D^+ D^- K^0$ and $Λ_b \to D^+ D^- Λ$ reactions by looking at the production mechanisms, with special emphasis in the final state interaction of the charmed mesons, which gives rise to the $X(3930)$, coupling strongly to $D_s\bar{D}_s$, and another state that we call $X(3700)$, coupling strongly to $D \bar D$ that qualifies as a $D \bar D$ bound state. The combined study of all these reactions shows that the final state interaction responsible for the production of these resonances is more important in the $B^+ \to D^+ D^- K^+$ reaction than in the $Λ_b \to D^+ D^- Λ$ one. We have taken this into account and shown that normalizing the $D^+ D^-$ mass distributions to the same value at the peak of the $ψ(3770)$ production, the two mass distributions are quite different in a range of 10 MeV above the $D^+ D^-$ threshold, with a value about an order of magnitude bigger for the $B^+ \to D^+ D^- K^+$ reaction than for the $Λ_b \to D^+ D^- Λ$ one. The $D^+D^-$ mass distribution by itself also shows an enhancement of about one order of magnitude in the presence of the $X(3700)$ with respect to a calculation where this resonance is absent. We make a call to measure these magnitudes in the coming LHCb upgrades, which would bring great support to the existence of the bound $D^+ D^-$ state.

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arXiv2026

Theoretical description of the $D^{+} \to \bar{K}^{0} π^{+} π^{0} π^{0}$ reaction

We study the $D^{+} \rightarrow \bar{K}^{0} π^{+} π^{0} π^{0}$ reaction, which shows two clear structures: the $\bar{K}^{*0}$ and $ρ^{+}$ in the $\bar{K}^{0} π^{0}$ and $π^{+} π^{0}$ mass distributions, respectively. The study is done starting from the quark level with external and internal emission and hadronizing a pair of quarks to produce a vector and two pseudoscalars. We also consider another mechanism, which does not require hadronization of quark pairs: the direct production of $\bar{K}^{*0}$ and $ρ^{+}$. With the help of six unknown parameters which are fitted to the data, we are able to get a very good agreement with experimental data for the $\bar{K}^{0} π^{0}$ and $π^{+} π^{0}$ mass distributions and a qualitative one for the rest of mass distributions which do not show any particular structure experimentally.

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arXiv2026

Study of the molecular Properties of the $P_c$ and $P_{cs}$ States

In the present work, we investigate the molecular properties of the hidden charm pentaquark states $P_c$ and $P_{cs}$ with a coupled channel framework that combines heavy quark spin symmetry and the local hidden gauge formalism. By solving the Bethe-Salpeter equation with the cutoff method, we obtain the pole trajectories, wave functions, and root-mean-square radii. For the hidden charm system, the full coupled channel interactions respecting the heavy quark spin symmetry are essential to generate the $P_c$ states, which significantly affect the poles' widths. The dominant bound channels are $\bar{D} Σ_c$ and $\bar{D}^* Σ_c$, which couple strongly to the lower decay channels. In contrast, for the hidden charm strange system, the full heavy quark spin symmetry treatment is not necessary, where the splitting PB and VB sectors yield similar results. The main bound channels $\bar{D} Ξ_c$ and $\bar{D}^* Ξ_c$ couple strongly to $\bar{D}_s Λ_c$ and $\bar{D}_s^* Λ_c$, respectively, but weakly to the lower decay channels, different from the hidden charm case. The trajectories of the pole widths for the loosely bound channels $\bar{D} Ξ'_c$, $\bar{D}^* Ξ'_c$, and $\bar{D}^* Ξ_c^*$ exhibit distinct behaviors. Notably, all the primary bound channels have similar binding energies in the single channel interactions due to equally attractive potentials. Furthermore, we also calculate the wave functions and root-mean-square radii of the corresponding poles. The wave functions are localized within $0\sim 6$ fm and vanish fast beyond $4$ fm. The root-mean-square radii, evaluated by two consistent methods, typically lie between $0.5$ and $2$ fm, comparable to the characteristic scale of molecular states. The root-mean-square radii depend on the pole trajectories and differ among the full coupled channel case, the split PB and VB sectors, and the single channel interactions.

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arXiv2026

Investigation of the $D^{0} \rightarrow K_S^{0} π^{0} η,\ K_S^{0} π^{0} π^0$ decays

Inspired by the invariant mass distributions for the decays $D^{0} \rightarrow K_S^{0} π^{0} η$ and $D^{0} \rightarrow K_S^{0} π^{0} π^{0}$ reported by the BESIII Collaboration, we investigate these processes with an unified final state interaction formalism by incorporating both the $S$-wave pseudoscalar meson-pseudoscalar meson interactions within a chiral unitary approach and the $P$-wave contribution from the intermediate resonance $\bar{K}^*(892)$. By performing a combined fit to the invariant mass spectra and taking into account the coherence between the $S$- and $P$-waves, our results are in agreement with the experimental data. For the decay $D^{0} \rightarrow K_S^{0} π^{0} η$, the structure near 1.0 GeV in the $π^0 η$ invariant mass distribution corresponds to the signal of the $a_{0}(980)$, which is dynamically generated from the $S$-wave interactions. In the case of $D^{0} \rightarrow K_S^{0} π^{0} π^{0}$, the near-threshold enhancement in the $π^0π^0$ mass distribution arises from the combined contributions of the $f_0(500)$ and the intermediate $\bar{K}^*(892)$, while the cusp-like structure around 1 GeV$^2$ is associated with the $f_0(980)$.

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arXiv2026

$a_0(980)$ production, triangle singularity, and non-$ϕ$ background in the $J/ψ\to ϕηπ^0$ reaction

We study the $J/ψ\toϕηπ^{0}$ reaction measured recently by the BESIII collaboration with high precision, paying attention to three important aspects: 1) The production of the $a_0(980)$ in the $π^0η$ mass distributions, with the typical narrow width observed in isospin violating processes; 2) The origin of two peaks in the $ϕπ^{0}$ mass distributions that were branded as ``non $ϕ$" contribution in the experimental analysis; 3) The existence of two triangle mechanisms developing a triangle sigularity at the same energy where the ``non $ϕ$" contribution peaks in the experiment. However, we also show that the strength of these peaks is very small relative to the observed ones, a feature which is tied to the experimental technique used to identify the $ϕ$ looking at $K^+K^-$ in a narrow window of invariant mass around the $ϕ$ mass. We suggest that these triangle singularities could be observed with other methods to identify the $ϕ$.

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arXiv2025

$J/ψΛ$ femtoscopy and the nature of $P_{ψs}^Λ(4338)$

Over the past two decades, numerous exotic hadron states have been discovered, yet their underlying nature remains unclear. It is widely acknowledged that understanding hadron-hadron interactions is essential to unraveling their properties. Hadron spectroscopy is a powerful tool for this endeavor, providing rich experimental data that can shed light on exotic systems. Recently, the LHCb experiment analyzed the process $B^{-} \rightarrow J/ψΛ\bar{p}$ and observed a narrow peak in the $J/ψΛ$ invariant mass spectrum, regarding it as a candidate for a pentaquark. In this work, we extract the coupled-channel $J / ψΛ-\bar{D} Ξ_c-\bar{D}_s Λ_c$ potential based on the $J/ψΛ$ invariant mass spectrum. Our results indicate the existence of a bound state below the $\bar{D} Ξ_c$ mass threshold, corresponding to the experimentally measured state $P_{cs}(4338)$. Furthermore, we predict the scattering lengths and momentum correlation functions for the $J/ψΛ$ and $\bar{D}Ξ_c$ channels, which serve as theoretical references for future femtoscopy experiments.

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arXiv2025

Revisiting the $Λ_c^+\to Ληπ^+$ and the roles of intermediate resonances

In this paper, we first review the theoretical and experimental studies of the process $Λ_c^+ \to π^+ ηΛ$. Motivated by the recent BESIII and Belle measurements, we have conducted a theoretical study of the process $Λ_c^+ \to π^+ ηΛ$, where the $a_0(980)$ and $Λ(1670)$ resonances are dynamically generated from the $S$-wave meson meson and meson baryon interaction, respectively. Our results give a reasonable description of the invariant mass distributions, which implies that the spin flip contribution in the $Σ(1385)$ excitation plays an important role.

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arXiv2025

Determination of the binding and $DK$ probability of the $D^{*}_{s0}(2317)$ from the $(\bar{D}\bar K)^-$ mass distributions in $Λ_{b}\to Λ_{c} (\bar{D}\bar K)^-$ decays

We study the $Λ_{b}\toΛ_{c}\bar{D}^{0}K^{-}$ and $Λ_{b}\to Λ_{c}D^{-}\bar{K}^{0}$ decays which proceed via a Cabibbo and $N_c$ favored process of external emission, and we determine the $\bar{D}^{0}K^{-}$ and $D^{-}\bar{K}^{0}$ mass distributions close to the $\bar{D} \bar{K}$ threshold. For this, we use the tree level contribution plus the rescattering of the meson-meson components, using the extension of the local hidden gauge approach to the charm sector that produces the $D^*_{s0}(2317)$ resonance. We observe a large enhancement of the mass distributions close to threshold due to the presence of this resonance below threshold. Next we undertake the inverse problem of extracting the maximum information on the interaction of the $\bar{D} \bar{K}$ channels from these distributions, and using the resampling method we find that from these data one can obtain precise values of the scattering lengths and effective ranges, the existence of an $I=0$ bound state with a precision of about $4 \;\rm MeV$ in the mass, plus the $\bar{D} \bar{K}$ molecular probability of this state with reasonable precision. Given the fact that the $Λ_{b}\toΛ_{c}\bar{D}^{0}K^{-}$ decay is already measured by the LHCb collaboration, it is expected that in the next runs with more statistics of the decay, these mass distributions can be measured with precision and the method proposed here can be used to determine the nature of the $D^*_{s0}(2317)$, which is still an issue of debate.

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arXiv2025

Role of $a_0(980)$ in the decays $D^{0} \rightarrow K^{+} K^{-} η$ and $π^{+} π^{-} η$

In present work, we study the reactions $D^{0} \rightarrow K^{+} K^{-} η$ and $D^0 \rightarrow π^{+} π^{-} η$, and find that the $a_0(980)$ state plays a dominant role. At the quark level, the external and internal $W$-emission mechanisms are taken into account, which can hadronize into the final states, and then the $a_0(980)$ state is generated from the final state interaction. Besides, the contributions of other intermediate resonances, such as $ρ(770)$ and $ϕ(1020)$, are also considered. We make a combined fit of the invariant mass spectra measured by the Belle and BESIII Collaborations, where the results are in good agreement with the experiments, and the signal of the $a_0(980)$ shows great significance. Besides, the antisymmetry data for the production of the $a_0(980)^+$ and $a_0(980)^-$ is described well in the combined fit.

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arXiv2024

Testing the molecular nature of the $Ω(2012)$ with the $ψ(3770) \to \barΩ \bar{K} Ξ$ and $ψ(3770) \to \barΩ \bar{K} Ξ^*(1530) (\bar Ω\bar K πΞ)$ reactions

We report on the reactions $ψ(3770)\to \barΩ^+ \bar{K} Ξ$ and $ψ(3770)\to \barΩ^+ \bar{K}Ξ^*(1530)~(Ξ^*(1530)\to πΞ$), and calculate the mass distributions $\frac{{\rm d}Γ}{{\rm d}M_\text{inv}(\bar{K}Ξ)}$ and $\frac{{\rm d}Γ}{{\rm d}M_\text{inv}(\bar{K}Ξ^*)}$, respectively. We obtain clear peaks corresponding to the $Ω(2012)$. From the decay of $ψ(3770)\to \barΩ^+ \bar{K}Ξ^*$, we also get a second, broader, peak around $2035\,\rm MeV$, which comes from the $Ω(2012)$ decay to $\bar{K}Ξ^*$. This second peak is closely tied to the molecular picture of the $Ω(2012)$ with the $\bar{K}Ξ^*(1530)$ and $ηΩ$ components. Its observation would provide a boost to the molecular picture of the $Ω(2012)$.

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arXiv2024

How to unravel the nature of the $Σ^*(1430) (1/2^-)$ state from correlation functions

We calculate the correlation functions for the $\bar K^0 p, π^+ Σ^0, π^0 Σ^+, π^+ Λ$, and $ηΣ^+$ states, which in the chiral unitary approach predict an excited $Σ^*(1/2^-)$ state at the $\bar K N$ threshold, recently observed by the Belle Collaboration. Once this is done, we tackle the inverse problem of seeing how much information one can obtain from these correlation functions. With the resampling method, one can determine the scattering parameters of all the channels with relative precision by means of the analysis in a general framework, and find a clear cusplike structure corresponding to the $Σ^*(1/2^-)$ in the different amplitudes at the $\bar{K}N$ threshold.

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arXiv2024

One or two poles for the $Ξ(1820)$?

In this talk, we present a new interpretation for the recently observed $Ξ(1820)$ resonance. We recall that the chiral unitary approach for the interaction of pseudoscalar mesons with the baryons of the decuplet predicts two states for the $Ξ(1820)$ resonance, one with a narrow width and the other one with a large width. We contrast this fact with the recent BESIII measurement of the $K^- Λ$ mass distribution in the $ψ(3686)$ decay to $K^- Λ\barΞ^+ $, which demands a width much larger than the average of the PDG, and show how the consideration of the two $Ξ(1820)$ states provides a natural explanation to this apparent contradiction.

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arXiv2024

The $Λ_c^+\toηπ^+Λ$ reaction and the $Λa_0^+(980)$ and $π^+Λ(1670)$ contributions

We study from the theoretical point of view the $Λ_c^+\to π^+ ηΛ$ reaction, recently measured by the Belle and BESIII Collaborations, where clear signals are observed for $a_0(980)$, $Λ(1670)$, and $Σ(1385)$ excitation. By considering the $a_0(980)$ and $Λ(1670)$ as dynamically generated resonances from the meson meson and meson baryon interaction, respectively, we are able to determine their relative production strength in the reaction, which is also tied to the strength of the $π^+ ηΛ$ tree level contribution. We observe that this latter strength is very big and there are large destructive interferences between the tree level and the rescattering terms where the $a_0(980)$ and $Λ(1670)$ are generated. The $Σ(1385)$ contribution is included by means of a free parameter, the only one of the theory, up to a global normalization, when one considers only external emission, and we observe that the spin flip part of this term, usually ignored in theoretical and experimental works, plays an important role determining the shape of the mass distributions. Internal emission is also considered and it is found to play a minor role.

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arXiv2024

The $X(4500)$ state considered as the mixture of hadronic molecule and diquark-antidiquark within effective field theory

In the present work, we construct the Lagrangians including three-meson, meson-diquark-antidiquark vertices, such that the diquark-antidiquark component as well as the molecular component are introduced within the effective field theory. With the obtained effective potentials projecting to spin 0, 1 and 2, we solve the Bethe-Salpeter equation with the on-shell approximation, and find that $X(4500)$ can be explained as the mixture of components $D_{s}^{*+}D_{s}^{*-}$, ${A}_{cq}\bar{A}_{cq}$ and ${A}_{cs}\bar{A}_{cs}$ with $I^G(J^{PC})=0^+(0^{++})$. In addition, another two resonances with quantum numbers $I^G(J^{PC})=0^+(1^{++})$ and $I^G(J^{PC})=0^+(2^{++})$ are predicted.

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arXiv2024

Possible signal of an exotic $I=1$, $J=2$ state in the $B \to D^{*-}D^+K^+$ reaction

We study the \proc reaction, showing that a peak in the \dk mass distribution around 2834 MeV reported by LHCb could be associated with a theoretical exotic state with that mass, a width of 19 MeV and $J^P=2^+$, stemming from the interaction of the $D^{*+}K^{*+}$ and $D^{*+}_s ρ^+$ channels, which is a partner of the $0^+$ $T_{c\bar{s}}(2900)$. We show that the data is compatible with this assumption, but also see that the mass distribution itself cannot discriminate between the spins $J=0$, $1$, $2$ of the state. Then we evaluate the momenta of the angular mass distribution and show that they are very different for each of the spin assumptions, and that the momenta coming from interference terms have larger strength at the resonant energy than the peaks seen in the angular integrated mass distribution. We make a call for the experimental determination of these magnitudes, which has already been used by the LHCb in related decay reactions.

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arXiv2024

Possible molecules of triple-heavy pentaquarks within the extended local hidden gauge formalism

In this study, we explore the interactions between mesons and baryons in the open heavy sectors to identify potential triple-heavy molecular pentaquarks. We derive the meson-baryon interaction potentials using the vector meson exchange mechanism within the extended local hidden gauge formalism. The scattering amplitudes are computed by solving the coupled-channel Bethe-Salpeter equation, revealing several bound systems. By analyzing the poles of these amplitudes in the complex plane, we determine the masses and widths of these bound states. Additionally, we evaluate the couplings and compositeness of different channels within each bound system to assess their molecular characteristics. Our predictions include four $Ω_{ccc}$-like states, four $Ω_{bbb}$-like states, fourteen $Ω_{bcc}$-like states, and ten $Ω_{bbc}$-like states, which could be targets for future experimental investigations.

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arXiv2024

$\bar{B}_s^0 \to D_{s1}(2460)^+ K^-, D_{s1}(2536)^+ K^-$ and the nature of the two $D_{s1}$ resonance

Starting from the molecular picture for the $D_{s1}(2460)$ and $D_{s1}(2536)$ resonances, which are dynamically generated by the interaction of coupled channels, the most important of which are the $D^*K$ for the $D_{s1}(2460)$ and $DK^*$ for the $D_{s1}(2536)$, we evaluate the ratio of decay widths for the $\bar{B}_s^0 \to D_{s1}(2460)^+ K^-$ and $\bar{B}_s^0 \to D_{s1}(2536)^+ K^-$ decays, the latter of which has been recently investigated by the LHCb collaboration, and we obtain a ratio of the order of unity. The present results should provide an incentive for the related decay into the $D_{s1}(2460)$ resonance to be performed, which would provide valuable information on the nature of these two resonances.

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arXiv2024

Correlation function and the inverse problem in the $BD$ interaction

We study the correlation functions of the $B^0 D^+, B^+ D^0$ system, which develops a bound state of approximately $40$ MeV, using inputs consistent with the $T_{cc}(3875)$ state. Then we address the inverse problem starting from these correlation functions to determine the scattering observables related to the system, including the existence of the bound state and its molecular nature. The important output of the approach is the uncertainty with which these observables can be obtained, considering errors in the $B^0 D^+, B^+ D^0$ correlation functions typical of current values in present correlation functions. We find that it is possible to obtain scattering lengths and effective ranges with relative high precision and the existence of a bound state. Although the pole position is obtained with errors of the order of $50 \%$ of the binding energy, the molecular probability of the state is obtained with a very small error of the order of $6\%$. All these findings can serve as motivation to perform such measurements in future runs of high energy hadron collisions.

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