arXiv subjects

Wei-Hong Liang

Publications and source records attributed to Wei-Hong Liang.

At least 37 records · Page 2Linked to original sources

arXiv2024

Determination of the $K^{+}\bar{K}^{0}$ scattering length and effective range and its relation to the $a_{0}^{+}(980)$ from the $χ_{c1}\toπ^{+}π^{-}η$ reaction

We analyze the clean cusp, seen in the $ηπ$ mass distribution with high precision of the $χ_{c1} \to ηπ^+ π^-$ reaction in the BESIII experiment, with the aim of making a precise determination of the scattering length $a$ and effective range $r_0$ of $K^+ \bar{K}^{0}$. For that, we follow a previous theoretical work that gave a good reproduction of these data using the chiral unitary approach for the meson-meson interaction, and allow some flexibility in the input to carry a better fit to the data. The important task of determining the uncertainties in the scattering parameters is done using the resampling method and an accuracy in $a$ and $r_0$ is obtained better than $20\%$. The effective range is determined for the first time with this analysis.

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arXiv2024

Study of possible $DND^*$ bound states

We start from a recently favored picture in which the $Λ_c(2940)$ and $Λ_c(2910)$ correspond mostly to $ND^*$ bound states with $J^P = 1/2^-,\, 3/2^-$ and then add a $D$ as a third particle, looking for the possible binding of the $DND^*$ three body system within the framework of the Fixed Center Approximation. We find that the system is bound with respect to the corresponding $Λ_c^* D$ threshold with a binding of about $60$ MeV and a width of about $90$ MeV. Alternatively we assume a cluster of $ND$ and a $D^*$ meson interacting with the cluster and we find similar results. The observation of these states of $J^P = 1/2^+,\, 3/2^+$ would provide new and valuable information concerning the $DN$ and $D^* N$ interaction, an issue of current debate.

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arXiv2024

Searching for the two poles of the $Ξ(1820)$ in the $ψ(3686) \to \barΞ^+ \bar{K}^0 Σ^{*-}(π^- Λ)$ decay

We propose the reaction $ψ(3686) \to \barΞ^+ \bar{K}^0 Σ^{*-}$, with the $Σ^{*-}$ decaying to $π^- Λ$ in order to show evidence for the existence of two $Ξ(1820)$ states, one around $1824$ MeV and narrow, and another one around $1875$ MeV and wide. The phase space for $\bar{K}^0 Σ^{*-}$ production reduces the effect of the lower mass resonance, magnifying the effect of the higher mass resonance that shows clearly over the phase space. The estimated rate of the production is bigger than the one of the $ψ(3686) \to \barΞ^+ K^- Λ$ reaction, where a clear peak for $Ξ(1820)$ was observed by the BESIII collaboration, what makes the Beijing facility ideal to carry out the reaction proposed.

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arXiv2024

The $Ω_c \to π^+ \, (π^0,\, η)\, πΞ^*$ reactions and the two $Ξ(1820)$ states

We have studied the $Ω_c \to π^+ (π^0, η) πΞ^*$ decays, where the final $πΞ^*$ comes from the decay of two resonances around the nominal $Ξ(1820)$, which are generated from the interaction of coupled channels made of a pseudoscalar and a baryon of the decuplet. The $πΞ^*$ mass distributions obtained in the six different reactions studied are quite different and we single out four of them, which are free of a tree level contribution, showing more clearly the effect of the resonances. The lower mass resonance is clearly seen as a sharp peak, but the higher mass resonance manifests itself through an interference with the lower one that leads to a dip in the mass distribution around $1850 \, {\rm MeV}$. Such a feature is similar to the dip observed in the $s$-wave $ππ$ cross section around the $980 \, {\rm MeV}$ coming from the interference of the $f_0(500)$ and $f_0(980)$ resonances. Its observation in coming upgrades of present facilities will shed light on the existence of these two resonances and their nature.

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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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arXiv2024

$\bar B^0 \to \bar K^{() \,0} X$, $B^- \to K^{() \, -} X$, $\bar B_s^0 \to η(η', ϕ) X$ from the $X(3872)$ molecular perspective

We study the decays $\bar B^0 \to \bar K^0 \, X$, $B^- \to K^- \, X$, $\bar B^0_s \to η(η')\, X$, $\bar B^0 \to \bar K^{*0} \, X$, $B^- \to K^{*-} \, X$ , $\bar B_s^0 \to ϕ\, X$, with $X \equiv X(3872)$, from the perspective of the $X(3872)$ being a molecular state made from the interaction of the $D^{*+} D^-, D^{*0} \bar D^0$ and $c.c.$ components. We consider both the external and internal emission decay mechanisms and find an explanation for the $\bar K^0 \, X$ and $K^- \, X$ production rates, based on the mass difference of the charged and neutral $D^* \bar D$ components. We also find that the internal and external emission mechanisms add constructively in the $\bar B^0 \to \bar K^0 \, X$, $B^- \to K^- \, X$ reactions, while they add destructively in the case of $\bar B^0 \to \bar K^{*0} \, X$, $B^- \to K^{*-} \, X$ reactions. This feature explains the decay widths of the present measurements and allows us to make predictions for the unmeasured modes of $\bar B^0_s \to η(η')\, X(3872)$ and $B^- \to K^{*-} \, X(3872)$. The future measurement of these decay modes will help us get a better perspective on the nature of the $X(3872)$ and the mechanisms present in production reactions of that state.

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arXiv2024

Correlation functions for the $N^*(1535)$ and the inverse problem

The $N^*(1535)$ can be dynamically generated in the chiral unitary approach with the coupled channels, $K^0 Σ^+, K^+ Σ^0, K^+ Λ$ and $ηp$. In this work we evaluate the correlation functions for every channel and face the inverse problem. Assuming the correlation functions to correspond to real measurements, we conduct a fit to the data within a general framework in order to extract the information contained in these correlation functions. The bootstrap method is used to determine the uncertainties of the different observables, and we find that, assuming errors of the same order than in present measurements of correlation functions, one can determine the scattering length and effective range of all channels with a very good accuracy. Most remarkable is the fact that the method predicts the existence of a bound state of isospin $\frac{1}{2}$ nature around the mass of the $N^*(1535)$ with an accuracy of $6\; \rm MeV$. These results should encourage the actual measurement of these correlation functions (only the $K^+ Λ$ one is measured so far), which can shed valuable light on the relationship of the $ N^*(1535)$ state to these coupled channels, a subject of continuous debate.

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arXiv2024

Contrasting observables related to the $N^*(1535)$ from the molecular or a genuine structure

In this work we compare the predictions for the scattering length and effective range of the channels $K^0 Σ^+, K^+ Σ^0 , K^+ Λ$ and $ηp$, assuming the $N^*(1535)$ state as a molecular state of these channels, or an original genuine state, made for instance from three quarks. Looking at very different scenarios, what we conclude is that the predictions of these two pictures are drastically different, to the point that we advise the measurement of these magnitudes, accessible for instance by measuring correlation functions, in order to gain much valuable information concerning the nature of this state.

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arXiv2024

$D^+ \to K_s^0 π^+ η$ reaction and $a_0(980)^+$

We study the $D^+ \to \bar K^0 π^+ η$ reaction where the $a_0(980)$ excitation plays a dominant role. We consider mechanisms of external and internal emission at the quark level, hadronize the $q \bar q$ components into two mesons and allow these mesons to undergo final state interaction where the $a_0(980)$ state is generated. While the $a_0(980)$ production is the dominant term, we also find other terms in the reaction that interfere with this production mode and, through interference with it, lead to a shape of the $a_0(980)$ significantly different from the one observed in other experiments, with an apparently much larger width.

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arXiv2024

$J/ψ$ decays into $ω(ϕ) f_1(1285)$ and $ω(ϕ) \,''f_1(1420)''$

We perform a theoretical study of the $J/ψ\to ω(ϕ) K^* \bar{K} + c.c. \to ω(ϕ) K^0 π^+ K^-$ reactions with the assumption that the $f_1(1285)$ is dynamically generated from a single channel $K^* \bar{K} + c.c$ interaction in the chiral unitary approach. Two peaks in the $K^0 π^+ K^-$ invariant mass distribution are observed, one clear peak locates at the $f_1(1285)$ nominal mass, the other peak locates at around $1420\; \rm MeV$ with about $70 \;\rm MeV$ width. We conclude that the former peak is associated with the $f_1(1285)$ and the latter peak is not a genuine resonance but a manifestation of the kinematic effect in the higher energy region caused by the $K^* \bar{K} + c.c.$ decay mode of the $f_1(1285)$.

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arXiv2024

Molecular pentaquark states with open charm and bottom flavors

We study the possibly-existing molecular pentaquark states with open charm and bottom flavors, {\it i.e.}, the states with the quark contents $c\bar{b}qqq$ and $b\bar{c}qqq$ ($q=u,d,s$). We investigate the meson-baryon interactions through the coupled-channel unitary approach within the local hidden-gauge formalism, and extract the poles by solving the Bethe-Salpeter equation in coupled channels. These poles qualify as molecular pentaquark states, which are dynamically generated from the meson-baryon interactions through the exchange of vector mesons. Our results suggest the existence of the $Σ_c^{(*)} B^{(*)}$ and $Σ_b^{(*)} \bar{D}^{(*)}$ molecular states with isospin $I=1/2$, the $Ξ_c^{(\prime,*)} B^{(*)}$ and $Ξ_b^{(\prime,*)} \bar{D}^{(*)}$ molecular states with isospin $I=0$ and $I=1$, as well as the $Ω_c^{(*)} B^{(*)}$ and $Ω_b^{(*)} \bar D^{(*)}$ molecular states with isospin $I=1/2$.

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arXiv2024

On the molecular nature of the $Ω_c(3120)$ and its analogy with the $Ω(2012)$

We make a study of the $Ω_c(3120)$, one of the five $Ω_c$ states observed by the LHCb collaboration, which is well reproduced as a molecular state from the $Ξ^*_c \bar K$ and $Ω^*_c η$ channels mostly. The state with $J^P = 3/2^-$ decays to $Ξ_c \bar K$ in $D$-wave and we include this decay channel in our approach, as well as the effect of the $Ξ^*_c$ width. With all these ingredients, we determine the fraction of the $Ω_c(3120)$ width that goes into $Ξ_c π\bar K$, which could be a measure of the $Ξ^*_c \bar K$ molecular component, but due to a relatively big binding, compared to its analogous $Ω(2012)$ state, we find only a small fraction of about 3%, which makes this measurement difficult with present statistics. As an alternative, we evaluate the scattering length and effective range of the $Ξ^*_c \bar K$ and $Ω^*_c η$ channels which together with the binding and width of the $Ω_c(3120)$ state, could give us an answer to the issue of the compositeness of this state when these magnitudes are determined experimentally, something feasible nowadays, for instance, measuring correlation functions.

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arXiv2023

The $\bar B_s^0 \to J/ψπ^0 η$ decay and the $a_0(980)-f_0(980)$ mixing

We study the $\bar B_s^0 \to J/ψf_0(980)$ and $\bar B_s^0 \to J/ψa_0(980)$ reactions, and pay attention to the different sources of isospin violation and mixing of $f_0(980)$ and $a_0(980)$ resonances where these resonances are dynamically generated from meson-meson interaction. We find that the main cause of isospin violation is the isospin breaking in the meson-meson transition $T$ matrices, and the other source is that the loops involving kaons in the production mechanism do not cancel due to the different masses of the charged and neutral kaons. We obtain a branching ratio for $a_0(980)$ production of the order of $5 \times 10^{-6}$. Future experiments can address this problem, and the production rate and shape of the $π^0 η$ mass distribution will definitely help to better understand the nature of scalar resonances.

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arXiv2023

Theoretical interpretation of the $Ξ(1620)$ and $Ξ(1690)$ resonances seen in $Ξ_c^+ \to Ξ^- π^+ π^+$ decay

We study the Belle reaction $Ξ_c^+ \to Ξ^- π^+ π^+$ looking at the mass distribution of $π^+ Ξ$, where clear signals for the $Ξ(1620)$ and $Ξ(1690)$ resonances are seen. These two resonances are generated dynamically from the interaction in coupled channels of $πΞ, \bar K Λ, \bar K Σ$ and $ηΞ$ within the chiral unitary approach. Yet, the weak decay process at the quark level, together with the hadronization to produce pairs of mesons, does not produce the $ππΞ$ final state. In order to produce this state one must make transitions from the $\bar K Λ, \bar K Σ$ and $ηΞ$ components to $πΞ$, and this interaction is what produces the resonances. So, the reaction offers a good test for the molecular picture of these resonances. Adding the contribution of the $Ξ^*(1530)$ and some background we are able to get a good reproduction of the mass distribution showing the signatures of the two resonances as found in the experiment.

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arXiv2023

Two states for the $Ξ(1820)$ 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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arXiv2022

Interpretation of the $Ω_c \to π^+ Ω(2012) \to π^+(\bar{K} Ξ)$ relative to $Ω_c \to π^+\bar{K} Ξ$ from the $Ω(2012)$ molecular perspective

We present a mechanism for $Ω_c \to π^+ Ω(2012)$ production through an external emission Cabibbo favored weak decay mode, where the $Ω(2012)$ is dynamically generated from the interaction of $\bar{K}Ξ^*(1530)$, $ηΩ$, with $\bar{K}Ξ$ as the main decay channel. The $Ω(2012)$ decays later to $\bar{K}Ξ$ in this picture, with results compatible with Belle data. The picture has as a consequence that one can evaluate the direct decay $Ω_c^0 \to π^+K^- Ξ^0$ and the decay $Ω_c^0 \to π^+\bar{K} Ξ^*$, $π^+ηΩ$ with direct coupling of $\bar{K}Ξ^*$ and $ηΩ$ to $K^- Ξ^0$. We show that, within uncertainties and using data from a recent Belle measurement, all these three channels account for about (12-20)\% of the total $Ω_c \to π^+K^- Ξ^0$ decay rate. The consistency of the molecular picture with all the data is established by showing that $Ω_c \to Ξ^0 \bar{K}^{*0} \to Ξ^0K^- π^+$ together with $Ω_c \to π^+ Ω^* \to π^+K^- Ξ^0 $ account for about 85\% of the total $Ω_c \to π^+K^- Ξ^0 $.

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arXiv2021

The $D_s^+ \to a_0(980) e^+ ν_e$ reaction and the $a_0(980)-f_0(980)$ mixing

We perform a study of the $D_s^+ \to a_0(980)(f_0(980)) e^+ ν_e$ reactions investigating the different sources of isospin violation which make the production of the $a_0(980)$ possible. We find that loops involving kaons in the production mechanism provide a source of isospin violation since they do not cancel due to the different mass of charged and neutral kaons, but we also find that the main source comes from the breaking of isospin in the meson-meson transition $T$ matrices, which contain information on the nature of the low lying scalar mesons. The reaction is thus very sensitive to the nature of the $a_0(980)$ and $f_0(980)$ resonances. Our results are consistent with the present upper bound for $a_0(980)$ production and only a factor three smaller, indicating that future runs with more statistics should find actual numbers for this reaction from where we can learn more about the origin of the scalar resonances and their nature.

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