arXiv subjects

Dian-Yong Chen

Publications and source records attributed to Dian-Yong Chen.

At least 91 records · Page 5Linked to original sources

arXiv2020

Towards the decay properties of deuteron-like state $d_{NΩ}$

Recent lattice QCD calculations showed that a $d_{NΩ}$ dibaryon state similar to the deuteron with small binding energy may exist. In this work we propose a hadronic molecular approach to study the dynamical properties of this exotic state. We use a phenomenological Lagrangian approach to describe the coupling of the $d_{NΩ}$ state to its constituents and the decays into conventional hadrons, $d_{NΩ} \to ΛΞ$ and $d_{NΩ} \to ΣΞ$. Predictions for the sum of the decay rates are in the range of a few hundred keV. In addition, we find that the $d_{NΩ} \to ΛΞ$ mode is dominant, preferably searched for in a future RHIC experiment.

hep-ph↗

arXiv2020

Masses of fully heavy tetraquarks $QQ \bar Q \bar Q$ in an extended relativized quark model

Inspired by recent measurement of possible fully charmed tetraquarks in LHCb Collaboration, we investigate the mass spectra of fully heavy tetraquarks $QQ \bar Q \bar Q$ in an extended relativized quark model. Our estimations indicate that the broad structure around 6.4 GeV should contain one or more ground $cc \bar c \bar c$ tetraquark states, while the narrow structure near 6.9 GeV can be categorized as the first radial excitation of $cc \bar c \bar c$ system. Moreover, with the wave functions of the tetraquarks and mesons, the strong decays of tetraquarks into heavy quarkonium pair are qualitatively discussed, which can be further checked by the LHCb and CMS Collaborations.

hep-ph↗

arXiv2020

Masses of doubly heavy tetraquarks $T_{QQ^\prime}$ in a relativized quark model

In the present work, the mass spectra of doubly heavy tetraquarks $T_{QQ^\prime}$ are systematically investigated in a relativized quark model. The four-body systems including the Coulomb potential, confining potential, spin-spin interactions, and relativistic corrections are solved within the variational method. Our results suggest that the $IJ^P=01^+$ $bb \bar u \bar d$ state is 54 MeV below the relevant $\bar B \bar B$ and $\bar B \bar B^*$ thresholds, which indicates that both strong and electromagnetic decays are forbidden, and thus this state can be a stable one. Its large hidden color component and small root mean square radius demonstrate that it is a compact tetraquark rather than a loosely bound molecule or point-like diquark-antidiquark structure. Our predictions of the doubly heavy tetraquarks may provide valuable information for future experimental searches.

hep-ph↗

arXiv2020

Reconciling the X(2240) with the Y(2175)

In the present work, we reanalyzed the cross sections for $e^+ e^- \to K^+K^-$, where a new structure $X(2240)$ was reported by BES III Collaboration. By including the interference between the direct coupling and vector meson intermediate processes, we find the mass and width of $X(2240)$ are $2197.4\pm 4.4$ MeV and $75.6\pm 7.2 $ MeV, respectively, which are well consistent with the PDG average values of the resonance parameters for $Y(2175)$, thus, we conclude that the $X(2240)$ should be the same state as the $Y(2175)$.

hep-ph↗

arXiv2020

Electric transitions of the charmed-strange mesons in a relativistic quark model

In the present work, we adopt a relativistic constituent quark model to depict the charmed strange meson spectroscopy, in which $D_{s0}(2317)$ and $D_{s1}(2460)$ are considered as the $1^3P_0$ and $1P_1^\prime$ charmed strange mesons, respectively. By using the wave function obtained from the relativistic quark model, we further investigate the electric transitions between charmed strange mesons. We find the long wave length approximation is reasonable for the charmed strange meson radiative decay by comparing the results with different approximations. The estimated partial widths are all safely under the upper limits of the experimental data. Moreover, we find the branching ratio of $D_{s1}(2536) \to D_s^\ast γ/D_s γ$ are large enough to be detected, which could be searched by further experiments in Belle II and LHCb.

hep-ph↗

arXiv2020

Does the bottomonium counterpart of $X(3872)$ exist?

A narrow line shape peak at about 10615 MeV, just above the threshold in the $B\bar B^*$ channel, which can be regarded as the signal of bottomonium counterpart of $X(3872)$, $X_b$, is predicted by using the extended Friedrichs scheme. Though a virtual state is found at about 10593 MeV in this scheme, we point out that the peak is contributed mainly by the coupling form factor, which comes from the convolution of the interaction term and meson wave functions including the one from $χ_{b1}(4P)$, but not mainly by the virtual-state pole. In this picture, the reason why $X_b$ signal is not observed in the $Υπ^+π^-$ and $Υπ^+π^-π^0$ channels can also be understood. The $χ_{b1}(4P)$ mass and width are found to be about 10771 MeV and 6 MeV, respectively and a dynamically generated broad resonance is also found with its mass and width at about 10672 MeV and 78 MeV, respectively. The line shapes of these two states are also affected by the form factor effect. Thus, this study also emphasizes the importance of the structure of the wave functions of high radial excitations in the analysis of the line shapes, and provides a caveat that some signals may be generated from the structures of the form factors rather than from poles.

hep-ph↗

arXiv2020

Production of $P-$wave charmed and charmed-strange mesons in pion and kaon induced reactions

In the present work, we investigate the production of $P-$wave charmed or charmed-strange mesons in the pion or kaon induced reactions on a proton target. The total cross sections as well as the differential cross sections depending on the scattering angle are evaluated in an effective Lagrangian approach. Our estimations indicate that magnitude of the cross sections strongly depends on the model parameter but such dependence can be almost completely canceled for the cross section ratios. These model independent ratios can be taken as a good criterion of the validity of heavy quark limit in the charmed region, which is helpful to understand $P$-wave charmed and charmed-strange mesons.

hep-ph↗

arXiv2019

Possible molecular states in $B^{()}B^{()}$ scatterings

We present that, if unitarizing the $B^{(*)}B^{(*)}$ scattering amplitudes in the constituent interchange model, one can find two bound state poles for $(I_{tot},S_{tot})=(0,1)$ $BB^*$ and $B^*B^*$ system, which corresponds to two $I(J^P)=0(1^+)$ doubly bottomed molecular states. Furthermore, it is noticed that the virtual states in $(1,0)$ $BB$, $(1,1)$ $BB^*$, $(1,0)$ $B^*B^*$, and $(1,2)$ $B^*B^*$ systems could produce enhancements of the module squares of the scattering $T$-matrix just above the related thresholds, which might correspond to $I(J^P)=1(0^+)$, $1(1^+)$, and $1(2^+)$ doubly bottomed molecular states, respectively. The calculation may be helpful for searching for the doubly bottomed molecular state in future experiments.

hep-ph↗

arXiv2019

Molecular states from $Σ^{()}_c\bar{D}^{()}-Λ_c\bar{D}^{(*)}$ interaction

In this work, we systemically investigate the molecular states from the $Σ^{(*)}_c\bar{D}^{(*)}-Λ_c\bar{D}^{(*)}$ interaction with the help of the Lagrangians with heavy quark and chiral symmetries in a quasipotential Bethe-Salpeter equation (qBSE) approach. The molecular states are produced from isodoublet (I=1/2) $Σ_c\bar{D}$ interaction with spin parity $J^P=1/2^-$ and $Σ_c\bar{D}^*$ interaction with $1/2^-$ and $ 3/2^-$. Their masses and widths are consistent with the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ observed at LHCb. The states, $Σ_c^*\bar{D}^*(1/2^-)$, $Σ_c^*\bar{D}^*(3/2^-)$ and $Σ^*_c\bar{D}(3/2^-)$, are also produced with the same parameters. The isodoublet $Σ_c^*\bar{D}^*$ interaction with $5/2^-$, as well as the isoquartet (I=3/2) $Σ_c\bar{D}^*$ interactions with $1/2^-$ and $3/2^-$, $Σ_c^*\bar{D}^*$ interaction with $3/2^-$ and $5/2^-$, are also attractive while very large cutoff is required to produce a molecular state. We also investigate the origin of the widths of these molecular states in the same qBSE frame. The $Λ\bar{D}^*$ channel is dominant in the decays of the states, $Σ_c\bar{D}^*(1/2^-)$, $Σ_c\bar{D}^*(3/2^-)$, $Σ_c^*\bar{D}(3/2^-)$, and $Σ_c\bar{D}(1/2^-)$. The $Σ^*_c\bar{D}^*(1/2^-)$ state has large coupling to $Σ_c\bar{D}$ channel while the $Σ_c\bar{D}^*$, $Σ^*_c\bar{D}$ and $Λ_c\bar{D}^*$ channels provide similar contributions to the width of the $Σ^*_c\bar{D}^*(3/2^-)$ state. These results will be helpful to understand the current LHCb experimental results, and the three predicted states and the decay pattern of these hidden-charmed molecular pentaquarks can be checked in future experiments.

hep-ph↗

arXiv2019

$D$ wave charmonia

Inspired by the recent observations of the vector charmonium-like states at BES III Collaboration and $ψ(3842)$ at LHCb Collaboration, we comb the $D$ wave charmonium state in the present work. We first evaluate the possibility of $Y(4320)$ as $ψ(3^3D_1)$ by investigating its open charm decays in quark-pair creation model and we find the width of $Y(4320)$ can be reproduced in a reasonable parameter range. Moreover, we take $ψ(3770)$, $ψ(4160)$ and $Y(4320)$ as the scale of $1D$, $2D$ and $3D$ charmonia to estimate the open charm decays of other $D$ wave charmonia. The total and partial widths of $D$ wave charmonium states have been predicted, which could be tested by further measurements at LHCb and Belle II Collaborations.

hep-ph↗

arXiv2019

Exploring the molecular scenario of $P_c(4312)$, $P_c(4440)$, and $P_c(4457)$

In the present work, we assign the newly observed $P_c(4312)$ as a $I(J^P)= \frac{1}{2} (\frac{1}{2})^-$ molecular state composed of $Σ_c \bar{D}$, while $P_c(4440)$ and $P_c(4457)$ as $Σ_c \bar{D}^\ast$ molecular states with $I(J^P)= \frac{1}{2} (\frac{1}{2})^-$ and $\frac{1}{2} (\frac{3}{2})^-$, respectively. In this molecular scenario, we investigate the $P_c\to J/ψp$ process of these three states and further predict the ratios of the $\mathcal B(P_c\to J/ψp)$ and those of $\mathcal B(Λ_b\to P_c K)$ between these three states, which could serve as a crucial test of the present molecular scenario.

hep-ph↗

arXiv2019

Production of $P_c $ states from $Λ_b$ decay

In the present work, we investigate $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ production from $Λ_b$ decay in a molecular scenario by using an effective Lagrangian approach. We predict the ratio of the branching fraction of $Λ_b \to P_c K$, which is weakly dependent on our model parameter. We also find the ratios of the productions of the branching fractions of $Λ_b \to P_c K$ and $P_c \to J/ψp$ can be well interpreted in the molecular scenario. Moreover, the estimated branching fractions of $Λ_b \to P_c K$ are of order $10^{-6}$, which could be tested by further measurements in LHCb Collaboration.

hep-ph↗

arXiv2019

Constructing $J/ψ$ family with updated data of charmoniumlike $Y$ states

Based on the updated data of charmoniumlike state $Y(4220)$ reported in the hidden-charm %and open-charm channels of the $e^+e^-$ annihilation, we propose a $4S$-$3D$ mixing scheme to categorize $Y(4220)$ into the $J/ψ$ family. We find that the present experimental data can support this charmonium assignment to $Y(4220)$. Thus, $Y(4220)$ plays a role of a scaling point in constructing higher charmonia above 4 GeV. To further test this scenario, we provide more abundant information on the decay properties of $Y(4220)$, and predict its charmonium partner $ψ(4380)$, whose evidence is found by analyzing the $e^+e^-\to ψ(3686)π^+π^-$ data from BESIII. If $Y(4220)$ is indeed a charmonium, we must face how to settle the established charmonium $ψ(4415)$ in the $J/ψ$ family. In this work, we may introduce a $5S$-$4D$ mixing scheme, and obtain the information of the resonance parameters and partial open-charm decay widths of $ψ(4415)$, which do not contradict the present experimental data. Additionally, we predict a charmonium partner $ψ(4500)$ of $ψ(4415)$, which can be accessible at future experiments, especially, BESIII and BelleII. The studies presented in this work provide new insights to establish the higher charmonium spectrum.

hep-ph↗

arXiv2019

Charged charmoniumlike structures in the $e^+ e^- \to ψ(3686) π^+ π^-$ process based on the ISPE mechanism

In 2017, the BESIII Collaboration announced the observation of a charged charmonium-like structure in the $ψ(3686)π^\pm$ invariant mass spectrum of the $e^+ e^- \to ψ(3686) π^+ π^-$ process at different energy points, which enables us to perform a precise study of this process based on the initial single pion emission (ISPE) mechanism. In this work, we perform a combined fit to the experimental data of the cross section of $e^+ e^- \to ψ(3686) π^+ π^-$, and the corresponding $ψ(3686)π^\pm$ and dipion invariant mass spectra. Our result shows that the observed charged charmonium-like structure in $e^+ e^- \to ψ(3686) π^+ π^-$ can be well reproduced based on the ISPE mechanism, and that the corresponding dipion invariant mass spectrum and cross section can be depicted with the same parameters. In fact, it provides strong evidence that the ISPE mechanism can be an underlying mechanism resulting in such novel a phenomenon.

hep-ph↗

arXiv2019

General mathematical analysis on multiple solutions of interfering resonances combinations

When fitting cross sections with several resonances or interfering background and resonances, one usually obtains multiple solutions of parameters with equal fitting quality. In the present work, we find the source of multiple solutions for a combination of several resonances or interfering background and resonances by analyzing the mathematical structure of the Breit-Wigner function. We find that there are $2^n$ fitting solutions with equal quality for $n+1$ resonances, and the multiplicity of the interfering background and resonances depends on zeros of the amplitudes in the complex plane. We provide a simple, general method to infer all other solutions with equal fitting quality from a known solution.

hep-ph↗

arXiv2019

Production of $Z_c(3900$) and $Z_c(4020)$ in $B_c$ decay

In the present work, we propose to search the charmonium-like states $Z_c(3900$) and $Z_c(4020)$ in the $B_c$ decay. In an effective Lagrangian approach, the branching ratios of $B_c^+ \to Z_c(3900)^+ π^0$ and $B_c^+\to Z_c (4020)^+ π^0$ are estimated to be of order of $10^{-4}$ and $10^{-7}$, respectively. The large production rate of $Z_c(3900)$ could provide an important source of the production of $Z_c(3900)$ from the semi-exclusive decay of $b$-flavored hadrons reported by D0 Collaboration, which can be tested by the exclusive measurements in LHCb.

hep-ph↗

arXiv2019

Understanding the $η_cρ$ decay mode of $Z_c^{(\prime)}$ via the triangle loop mechanism

Recently, the BESIII Collaboration reported a new measurement of the $η_c ρ$ decay mode of $Z_c^{(\prime)}$, which motivated us to study the inner structure of $Z_c^{(\prime)}$ via investigating the hidden charm decays of these two $Z_c$ states. We consider the {triangle loop mechanism} contribution in the hidden charm decays of $Z_c^{(\prime)}$. Our estimations indicate that the triangle loop mechanism plays an important role in the decays of the $Z_c^{(\prime)}$, where our results are in agreement with the experimental observations in a reasonable parameter range. Furthermore, we point out that the $Z_c^{(\prime)}$ can be interpreted as the hadronic molecules, while the tetraquark scenario is less favored.

hep-ph↗

arXiv2019

Production of the $Z_b^{(\prime)}$ states from the $Υ(5S,6S)$ decays

In the present work, we investigate the production mechanism of the $Z_b(10610)$ and $Z_b(10650)$ states from the $Υ(5S,6S)$ decays. Two types of bottom-meson loops are discussed. We show that the loop contributions with all intermediate states being the $S$-wave ground state bottom mesons are negligible, while the loops with one bottom meson being the broad $B_0^\ast$ or $B_1^\prime$ resonance could provide the dominant contributions to the $Υ(5S) \to Z_b^{(\prime)} π$. It is found that such a mechanism is not suppressed by the large width of the $B_0/B_1'$ resonance. In addition, we also estimate the branching ratios for the $Υ(6S) \to Z_b^{(\prime)} π$ which could be tested by future precise measurements at Belle-II.

hep-ph↗