arXiv subjects

Dian-Yong Chen

Publications and source records attributed to Dian-Yong Chen.

At least 109 records · Page 6Linked to original sources

arXiv2019

The electromagnetic form factors of $Λ$ hyperon in the vector meson dominance model

We perform an analysis on the electromagnetic form factors of the $Λ$ hyperon in the time-like reaction $e^+e^-\rightarrow Λ\barΛ$ by using a modified vector meson dominance model. We consider both the intrinsic structure components and the meson clouds components. For the latter one, we not only include the contributions from the $ϕ$ and $ω$ mesons, but also take into account the contributions from the resonance states $ω(1420)$, $ω(1650)$, $ϕ(1680)$ and $ϕ(2170)$. We extract the model parameters by combined fit to the time-like effective form factor $|G_{\rm{eff}}|$, the electromagnetic form factor ratio $|G_E/G_M|$ and the relative phase $ΔΦ$ of the $Λ$ hyperon from the BaBar and BESIII Collaborations. We find that the vector meson dominance model can simultaneously describe these observables. Particularly, the inclusion of the resonance states in the model is necessary for explaining the ratio $|G_E/G_M|$ in a wide range of $\sqrt{s}$ as well as the large phase angle. With the fitted parameters, we predict the single and double polarization observables, which could be measured in polarized annihilation reactions. Moreover, we analytically continue the expression of the form factors to space-like region and estimate the space-like form factors of $Λ$ hyperon.

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arXiv2018

Hidden-strange molecular states and the $Nϕ$ bound state via a QCD van der Waals force

In this work, we study the hidden-strange molecular states composed of a baryon and a vector meson in a coupled-channel $Nρ-Nω-Nϕ-ΛK^*-ΣK^*$ interaction. With the help of the effective Lagrangians which coupling constants are determined by the SU(3) symmetry, the interaction is constructed and inserted into the quasipotential Bethe-Salpeter equation to search for poles in the complex plane, which correspond to molecular states. Two poles are found with a spin parity $3/2^-$ near the $Nρ$ and the $ΣK^*$ thresholds, which can be related to the $N(1700)$ and the $N(2100)$, respectively. No pole near the $Nϕ$ threshold can be found if direct interaction between a nucleon and $ϕ$ meson is neglected according to the OZI rule. After introducing the QCD van der Waals force between a nucleon and $ϕ$ meson, a narrow state can be produced near the $Nϕ$ threshold. Inclusion of the QCD van der Waals force changes the line shape of the invariant mass spectrum in the $Nϕ$ channel leading to a worse agreement with the present low-precision data. Future experiments at BelleII, JLab, and other facilities will be very helpful to clarify the existence of these possible hidden-strange molecular states.

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arXiv2018

Interference effect as resonance killer of newly observed charmoniumlike states $Y(4320)$ and $Y(4390)$

In this letter, we decode the newly observed charmoniumlike states, $Y(4320)$ and $Y(4390)$, by introducing interference effect between $ψ(4160)$ and $ψ(4415)$, which plays a role of resonance killer for $Y(4320)$ and $Y(4390)$. It means that two newly reported charmoniumlike states are not genuine resonances, according to which we can naturally explain why two well-established charmonia $ψ(4160)$ and $ψ(4415)$ are missing in the cross sections of $e^+e^- \to π^+ π^- J/ψ$ and $π^+ π^- h_c$ simultaneously. To well describe the detailed data of these cross sections around $\sqrt{s}=4.2$ GeV, our study further illustrates that a charmoniumlike structure $Y(4220)$ must be introduced. As a charmonium, $Y(4220)$ should dominantly decay into its open-charm channel $e^+e^- \to D^0 π^+ D^{\ast-}$, which provides an extra support to $ψ(4S)$ assignment to $Y(4220)$. In fact, this interference effect introduced to explain $Y(4320)$ and $Y(4390)$ gives a typical example of non-resonant explanations to the observed $XYZ$ states, which should be paid more attention especially before identifying the observed $XYZ$ states as genuine resonances.

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arXiv2017

$Z_c(3900)/Z_c(3885)$ as a virtual state from $πJ/ψ-\bar{D}^*D$ interaction

In this work, we study the $J/ψπ$ and $\bar{D}^*D$ invariant mass spectra of the $Y(4260)$ decay to find out the origin of the $Z_c(3900)$ and $Z_c(3885)$ structures. The $J/ψπ-\bar{D}^{*}D$ interaction is studied in a coupled-channel quasipotential Bethe-Saltpeter equation approach, and embedded to the $Y(4260)$ decay process to reproduce both $J/ψπ^-$ and $D^{*-}D^0$ invariant mass spectra observed at BESIII simultaneously. It is found out that a virtual state at energy about 3870 MeV is produced from the interaction when both invariant mass spectra are comparable with the experiment. The results support that both $Z_c(3900)$ and $Z_c(3885)$ have the same origin, that is, a virtual state from $J/ψπ-\bar{D}^*{D}$ interaction, in which the $\bar{D}^*{D}$ interaction is more important and the coupling between $\bar{D}^*{D}$ and $J/ψπ$ channels plays a minor role.

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arXiv2017

Interpretation of $Y(4390)$ as an isoscalar partner of $Z(4430)$ from $D^*(2010)\bar{D}_1(2420)$ interaction

Invoked by the recent observation of $Y(4390)$ at BESIII, which is about 40 MeV below the $D^*(2010)\bar{D}_1(2420)$ threshold, we investigate possible bound and resonance states from the $D^*(2010)\bar{D}_1(2420)$ interaction with the one-boson-exchange model in a quasipotential Bethe-Salpeter equation approach. A bound state with quantum number $0^-(1^{--})$ is produced at 4384 MeV from the $D^ (2010)\bar{D}_1(2420)$ interaction, which can be related to experimentally observed $Y(4390)$. Another state with quantum number $1^+(1^{+})$ is also produced at $4461+i39$ MeV from this interaction. Different from the $0^-(1^{--})$ state, the $1^+(1^{+})$ state is a resonance state above the $D^*(2010)\bar{D}_1(2420)$ threshold. This resonance state can be related to the first observed charged charmonium-like state $Z(4430)$, which has a mass about 4475 MeV measured above the threshold as observed at Belle and LHCb. Our result suggests that $Y(4390)$ is an isoscalar partner of the $Z(4430)$ as a hadronic-molecular state from the $D^*(2010)\bar{D}_1(2420)$ interaction.

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arXiv2017

Exploring the $Υ(6S)\to χ_{bJ}ϕ$ and $Υ(6S)\to χ_{bJ}ω$ hidden-bottom hadronic transitions

In this work, we investigate the hadronic loop contributions to the $Υ(6S) \to χ_{bJ} ϕ~(J=0,1,2)$ along with $Υ(6S) \to χ_{bJ} ω~(J=0,1,2)$ transitions. We predict that the branching ratios of $Υ(6S) \to χ_{b0} ϕ$, $Υ(6S) \to χ_{b1} ϕ$ and $Υ(6S) \to χ_{b2} ϕ$ are $(0.68 \sim 4.62) \times 10^{-6}$, $(0.50 \sim 3.43) \times 10^{-6}$ and $(2.22 \sim 15.18) \times 10^{-6}$, respectively and those of $Υ(6S) \to χ_{b0} ω$, $Υ(6S) \to χ_{b1} ω$ and $Υ(6S) \to χ_{b2} ω$ are $(0.15 \sim 2.81) \times 10^{-3}$, $(0.63 \sim 11.68) \times 10^{-3}$ and $(1.08 \sim 20.02) \times 10^{-3}$, respectively. Especially, some typical ratios, which reflect the relative magnitudes of the predicted branching ratios, are given, i.e., for $Υ(6S)\to χ_{bJ}ϕ$ transitions, $\mathcal{R}^ϕ_{10}={\mathcal{B}[Υ(6S) \to χ_{b1} ϕ]}/{\mathcal{B}[Υ(6S) \to χ_{b0} ϕ]} \approx 0.74$, $\mathcal{R}^ϕ_{20}= {\mathcal{B}[Υ(6S) \to χ_{b2} ϕ]}/{\mathcal{B}[Υ(6S) \to χ_{b0} ϕ]} \approx 3.28$, and $\mathcal{R}^ϕ_{21} = {\mathcal{B}[Υ(6S) \to χ_{b2} ϕ]}/{\mathcal{B}[Υ(6S) \to χ_{b1} ϕ]} \approx 4.43$, and for $Υ(6S)\to χ_{bJ}ω$ transitions, $\mathcal{R}^ω_{10}={\mathcal{B}[Υ(6S) \to χ_{b1} ω]}/{\mathcal{B}[Υ(6S) \to χ_{b0} ω]} \approx 4.11$, $\mathcal{R}^ω_{20}= {\mathcal{B}[Υ(6S) \to χ_{b2} ω]}/{\mathcal{B}[Υ(6S) \to χ_{b0} ω]} \approx 7.06$, and $\mathcal{R}^ω_{21} = {\mathcal{B}[Υ(6S) \to χ_{b2} ω]}/{\mathcal{B}[Υ(6S) \to χ_{b1} ω]} \approx 1.72$. With the running of BelleII in the near future, experimental measurement of these two kinds of transitions will be a potential research issue.

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arXiv2017

Possible hadronic molecular states composed of $S$-wave heavy-light mesons

We perform a systematical study of possible molecular states composed of the $S$ wave heavy light mesons, where the $S-D$ mixing and {$η-η^{\prime}$ mixing} are explicitly included. Our calculation indicates that the observed $X(3872)$ could be a loosely shallow molecular state composed of $D\bar{D}^\ast +h.c$, while neither $Z_c(3900)/Z_c(4020)$ nor $Z_b(10610)/Z_b(10650)$ is supported to be a molecule. Some observed possible molecular states are predicted, which could be searched for by further experimental measurements.

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arXiv2016

Where are $χ_{cJ}(3P)$?

In the present work, we propose $Y(4140)$ as the $χ_{c1}(3P)$ state by studying the $χ_{c1} π^+ π^-$ invariant mass spectrum of the $B\to K χ_{c1} π^+ π^-$ process. In the $D\bar{D}$ invariant mass spectrum of the $B\to K D\bar{D}$ process, we find a new resonance with the mass and width to be $ (4083.0 \pm 5.0) $ and $ (24.1 \pm 15.4) $ MeV, respectively, which could be a good candidate of the $χ_{c0}(3P)$ state. The theoretical investigations on the decay behaviors of the $χ_{cJ}(3P)$ in the present work support the assignments of the $Y(4140)$ and $Y(4080)$ as the $χ_{c1}(3P)$ and $χ_{c0}(3P)$ states, respectively. In addition, the $χ_{c2}(3P)$ state is predicted to be a very narrow state. The results in the present work could be tested by further experiments in the LHCb and forthcoming Belle II.

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arXiv2016

Revealing the inner structure of the newly observed $D_2^*(3000)$

Stimulated by the recent observation of the $D_2^\ast(3000)$, we study the decay behaviors of the $3P$ and $2F$ charmed mesons in the present work. By comparing the masses and decay properties of the $3^3P_2$ and $2^3F_2$ charmed mesons with the observation of the $D_2^\ast(3000)$, we conclude that the most possible assignment of the $D_2^\ast(3000)$ is the $3^3P_2$ charmed meson, while the assignment of the $2^3F_2$ charmed meson could not be fully exclude. The results of the unobserved $3P$ and $2F$ charmed mesons in this work could provide some fundamental information of searching for these charmed mesons in the further experiments by LHCb and forthcoming Belle II.

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arXiv2016

Prediction of anomalous $Υ(5S)\toΥ(1^3D_J)η$ transitions

In this work, we study the hadronic loop contribution to the $Υ(5S)\to Υ(1^3D_J)η$ ($J=1,2,3$) transitions. We predict that the branching ratios of $Υ(5S)\to Υ(1^3D_1)η$, $Υ(5S)\to Υ(1^3D_2)η$ and $Υ(5S)\to Υ(1^3D_3)η$ can reach up to $(0.5\sim5.1)\times10^{-3}$, $(0.7\sim7.5)\times10^{-3}$ and $(0.9\sim9.6)\times10^{-4}$, respectively. Since these predicted hadronic transitions of $Υ(5S)$ are comparable with these observed $Υ(5S)\to Υ(nS)π^+π^-$ $(n=1,2,3)$, we suggest future experiment like Belle and BelleII to carry out the search for these anomalous $Υ(5S)\to Υ(1^3D_J)η$ transitions.

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arXiv2016

$D_{s1}^(2860)$ and $D_{s3}^(2860)$: Candidates for $1D$ charmed-strange mesons

Newly observed two charmed-strange resonances, $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, are investigated by calculating their Okubo-Zweig-Iizuka allowed strong decays, which shows that they are suitable candidates for the $1^3D_1$ and $1^3D_3$ states in the charmed-strange meson family. Our study also predicts other main decay modes of $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, which can be accessible at the future experiment. In addition, the decay behaviors of the spin partners of $D_{s1}^*(2860)$ and $D_{s3}^*(2860)$, i.e., $1D(2^-)$ and $1D^\prime(2^-)$, are predicted in this work, which are still missing at present. Experimental search for the missing $1D(2^-)$ and $1D^\prime(2^-)$ charmed-strange mesons is an intriguing and challenging task for further experiment.

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arXiv2016

Radiative and pionic transitions from the $D_{s1}(2460)$ to the $D_{s0}^\ast(2317)$

We estimate the partial widths for the radiative and pionic transitions from the $D_{s1}(2460)$ to the $D_{s0}(2317)$ in a molecule scenario, in which the $D_{s1}(2460)$ and $D_{s0}^\ast(2317)$ are considered as hadronic molecule states of $DK$ and $D^\ast K$, respectively. The partial widths for the $D_{s1}(2460) \to D_{s0}^\ast(2317) π^0$ and $D_{s1}(2460) \to D_{s0}^\ast(2317) γ$ are evaluated to be about $0.19 \sim 0.22$ keV and $3.0 \sim 3.1$ keV, respectively. In addition, the ratio of the $D_{s1}(2460) \to D_{s0}(2317) γ$ and $D_{s1}(2460) \to D_{s}^\ast π^0$ is estimated to be about $(6.6\sim 10.6) \times 10^{-2}$, which is safely under the measured upper limit.

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arXiv2016

Possible $B^{(\ast)} \bar{K}$ hadronic molecule state

In the present work, we estimate the decays of the $X(5568)$ and $X(5616)$ in a $B \bar{K}$ and a $B^\ast \bar{K}$ $S$-wave hadronic molecule scenarios, respectively, which may corresponding to the structure observed by D0 Collaboration. Our estimation indicates both $B\bar{K}$ and $B^\ast \bar{K}$ hadronic molecule decay widths could explain the experimental data in a proper model parameter range.

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arXiv2016

Search for missing $ψ(4S)$ in the $e^+e^-\to π^+π^-ψ(2S)$ process

A detailed analysis to find a missing $ψ(4S)$ is made by utilizing the recent precise mesurements of the cross section for the process $e^+e^-\to ψ(2S)π^+π^-$ by Belle. Assuming three resonances $Y(4360)$, $Y(4660)$, and $ψ(4S)$ to fit the data, we obtain the resonance parameters for $ψ(4S)$ as $m=4243$ MeV and $Γ=16 \pm 31$ MeV showing a narrow state as predicted before. A combined fit to the data $e^+ e^- \to ψ(2S) π^+ π^-, \ h_c π^+ π^-$, and $χ_{c0} ω$ is also performed to obtain the similar resonance parameters of $ψ(4S)$. The upper limit of the branching ratio is fitted to be $\mathcal{B}(ψ(4S)\toψ(2S)π^+π^-) < 3\times 10^{-3}$, which can be understood by hadronic loop contributions in reasonable parameters range. In addition, the ratios of the branching ratios of the $ψ(4S)$ dipion transition to the one of $ψ(4S)\toχ_{c0}ω$ are fitted, which can be further measured by BESIII and forthcoming BelleII to confirm the existence of $ψ(4S)$.

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arXiv2016

Study on the rare decays of $Y(4630)$ induced by final state interactions

A resonance $Y(4630)$ at the invariant mass spectrum of $Λ_c \barΛ_c$ observed by the Belle Collaboration triggers a hot discussion about its inner structure. Since it preferably decays into two charmed baryons $Λ_c\barΛ_c$, it is tempted to conjecture it as a tetraquark. Because the dominant decay portal $Y(4630)\to Λ_c \barΛ_c$ is close to the energy threshold, the final state interactions may be significant and result in other baryonic and/or mesonic final states whose branching fractions are sizable to be measured in the future experiments. In this work we calculate the branching ratios of the $Y(4630)$ decays into $p\bar p$, $D^{(*)+} D^{(*)-}$, $π^+π^-$, and $K^+K^-$ which are induced by the $Λ_c \barΛ_c$ re-scattering. The resultant decay patterns will be tested by the future experiments and the consistency degree with the data composes a valuable probe for the tetraquark conjecture.

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arXiv2016

Using $X(3823)\to J/ψπ^+π^-$ to identify coupled-channel effects

Very recently, the Belle and BESIII experiments observed a new charmonium-like state $X(3823)$, which is a good candidate for the $D$-wave charmonium $ψ(1^3D_2)$. Because the $X(3823)$ is just near the $D\bar{D}^*$ threshold, the decay $X(3823)\to J/ψπ^+π^-$ can be a golden channel to test the significance of coupled-channel effects. In this work, this decay is considered including both the hidden-charm dipion and the usual quantum chromodynamics multipole expansion (QCDME) contributions. The partial decay width, the dipion invariant mass spectrum distribution $\mathrm{d}Γ[X(3823)\to J/ψπ^+π^-]/\mathrm{d}m_{π^+π^-}$, and the corresponding $\mathrm{d}Γ[X(3823)\to J/ψπ^+π^-]/\mathrm{d}\cosθ$ distribution are computed. Many parameters are determined from existing experimental data, so the results depend mainly only on one unknown phase between the QCDME and hidden-charm dipion amplitudes.

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arXiv2016

Radiative decays of the neutral $Z_c(3900)$

We study the radiative decays of the $Z_c(3900)^0$ in a hadronic molecule picture, where the $Z_c(3900)$ is treated as a $D \bar{D}^\ast +c.c$ hadronic molecule. The partial widths of $Γ(Z_c(3900)^0 \to γη_c(2S))$ and $Γ(Z_c(3900)^0 \to γχ_{c0})$ are predicted to be of order 10 keV and the cross sections for $σ(e^+ e^- \to π^0 Z_c(3900) \to π^0 γη_c(2S))$ and $σ(e^+ e^- \to π^0 Z_c(3900) \to π^0 γχ_{c0})$ are of order 0.1 pb at 4.23 GeV, which may be accessible for the BESIII and forthcoming BelleII.

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arXiv2016

Unified Fano-like interference picture for charmonium-like states $Y(4008)$, $Y(4260)$ and $Y(4360)$

We propose that the unified Fano-like interference picture applies to $e^+e^-\to π^+π^- J/ψ$ and $e^+e^-\to π^+π^- ψ(3686)$, where $Y(4260)$ and $Y(4360)$ are observed, respectively, to provide a reasonable interpretation of the asymmetric lines hapes of $Y(4260)$ and $Y(4360)$ structures. Moreover, the Fano-like interference induces an extra broad structure $Y(4008)$ in $e^+e^-\to π^+π^- J/ψ$ as a companion peak to $Y(4260)$. Three charmonium-like states $Y(4008)$, $Y(4260)$ and $Y(4360)$ observed in $e^+e^-$ annihilation processes are not genuine resonances. Under this scenario, it is well explained why $Y(4008)$, $Y(4260)$ and $Y(4360)$ are absent in the experimental data of the $R$ value scan and missing in open-charm decay channels. Although the present work presents a typical application of the Fano-like interference in particle physics at the lower energy region, we have reason to believe that the Fano-like phenomena may exist in other processes such as $e^+e^-\to π^+π^-ψ(3770)$ and $e^+e^-\to K^+K^- J/ψ$, which will be accessible at BESIII and forthcoming BelleII.

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