arXiv subjects

Jun-Zhang Wang

Publications and source records attributed to Jun-Zhang Wang.

At least 37 records · Page 2Linked to original sources

arXiv2023

The $X(3872)\rightarrow J/ψπγ$ and $X(3872)\rightarrow J/ψππγ$ decays

We study the $ρ$ and $ω$ meson contribution to the radiative decays $X(3872)\rightarrow J/ψπγ$ and $X(3872)\rightarrow J/ψππγ$. The $X(3872)\rightarrow J/ψπγ$ is dominated by the $ω$ meson. As for the $X(3872)\rightarrow J/ψππγ$, the contributions of the cascade decays through the $ρ$ and $ω$ mesons are strongly suppressed with respect to the diagrams which proceed either through the $ψ(2S)$ or the three body decay of $ρ$. The branching ratios of $X(3872)\rightarrow J/ψπγ$ and $X(3872)\rightarrow J/ψππγ$ are $(8.10^{+3.50}_{-2.88})\times10^{-3}$ and $(2.38\pm1.06)\%$, which may be accessible by the BESIII and LHCb Collaborations. Especailly, the $X(3872)\rightarrow J/ψπγ$ and $X(3872)\rightarrow J/ψπ^+π^- γ$ decays can be employed to extract the couplings $g_{Xψω}$ and $g_{Xψρ}$, which probe the isoscalar and isovector components of the X(3872) wave function respectively.

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arXiv2023

Confirming the existence of a new higher charmonium $ψ(4500)$ by the newly released data of $e^+e^- \to K^+K^- J/ψ$

Recently, the BESIII Collaboration published the Born cross section of $e^+e^- \to K^+K^- J/ψ$, in which a new vector enhancement structure $Y(4500)$ was observed for the first time. The mass of the $Y(4500)$ resonance structure is in good agreement with our previous prediction for a $5S$-$4D$ mixing charmonium candidate $ψ(4500)$, while the measured width is $2σ$ larger than the theoretical estimate. In this work, we reanalyzed the cross section of $e^+e^- \to K^+K^- J/ψ$ by introducing two theoretically predicted charmonium states $ψ(4220)$ and $ψ(4500)$ as intermediate resonances, and found that this width deviation problem can be resolved. Meanwhile, we found that the inclusion of two established charmonium states $ψ(4160)$ and $ψ(4415)$ can further improve the fit quality, with four sets of widely different solutions to $Γ_{e^+e^-} \mathcal{B}(ψ\to K^+K^- J/ψ)$. In order to better identify the properties of the $Y(4500)$, we calculated the charmonium hadronic transition to final states $K^+K^- J/ψ$ within the charmed meson loop mechanism, where the fitted branching ratio of $ψ(4500) \to K^+K^- J/ψ$ can be well explained by the theoretical calculation, further supporting the new enhancement structure around 4.5 GeV as a higher charmonium $ψ(4500)$ that we predicted. Finally, we also discussed the possible signal of another predicted charmonium candidate $ψ(4380)$ in $e^+e^- \to K^+K^- J/ψ$. These research results should be an important step in constructing the charmonium family and thoroughly solving the charmoniumlike $Y$ problem.

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arXiv2022

Connection between near the $D_s^+D_s^-$ threshold enhancement in $B^+ \to D_s^+D_s^-K^+$ and conventional charmonium $χ_{c0}(2P)$

Focusing on recent measurement of $B^+ \to D_s^+D_s^-K^+$ process given by the LHCb Collaboration, we propose that this newly observed near the $D_s^+D_s^-$ threshold enhancement can be due to the contribution of the $χ_{c0}(2P)$, which is a $P$-wave charmonium below the $D_s^+D_s^-$ threshold. By performing a combined fit to the measured $D_s^+D_s^-$, $D_s^+K^+$, and $D_s^-K^+$ invariant mass spectra, introducing the $χ_{c0}(2P)$ can well reproduce the near threshold enhancement in the $D_s^+D_s^-$ invariant mass spectrum. When depicting the whole $D_s^+D_s^-$ invariant mass spectrum, the contributions from higher charmonium $ψ(4230)$ and charmoniumlike state $X_0(4140)$ are obvious. In addition, a charmed meson $D^*(3^3S_1)$ with mass around 3015 MeV is found to be important to depict the $D_s^-K^+$ invariant mass spectrum well. Especially, the importance of node effect of the spatial wave function of the $χ_{c0}(2P)$ is revealed, by which the anomaly of the ratio $Γ(X\to D^+D^-)/Γ(X\to D_s^+D_s^-)$ indicated by LHCb can be explained well. Finally, our scenario of the newly observed enhancement structure resulted from the $χ_{c0}(2P)$ is enforced.

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arXiv2022

Improved understanding of the peaking phenomenon existing in the new di-$J/ψ$ invariant mass spectrum from the CMS Collaboration

Very recently, the CMS Collaboration reported a peaking phenomenon existing in the di-$J/ψ$ invariant mass spectrum from $pp$ collision, by which the $X(6900)$ structure announced by the LHCb Collaboration was confirmed, but also more enhancement structures were discovered. Facing such a novel phenomenon, in this work we indicate that these new features reflected from the CMS measurement provide a good implication for a dynamical mechanism which reproduces the novel peaking phenomenon in the reported $J/ψ$-pair mass spectrum well. This mechanism is due to special reactions, where different charmonium pairs directly produced by $pp$ collision may transit into the final state of $J/ψJ/ψ$. The present work provides a special viewpoint to decode these observed fully charm structures in the $J/ψ$-pair invariant mass spectrum.

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arXiv2022

The role of the $ω(4S)$ and $ω(3D)$ states in mediating the $e^+e^-\to ωη$ and $ωπ^0π^0$ processes

The $e^+e^-\to ωη$ and $e^+e^-\toωπ^0π^0$ processes are ideal platforms to search for higher $ω$ states. Focusing on the observations of two enhancement structures around 2.2 GeV existing in $e^+e^-\to ωη$ and $e^+e^-\toωπ^0π^0$ at BESIII, we analyze how the $ω(4S)$ and $ω(3D)$ states play the role in the $e^+e^-\to ωη$ and $e^+e^-\toωπ^0π^0$ processes. The present study is supported by theoretical $ω$ mesonic spectroscopy. For reproducing the data of the cross sections of $e^+e^-\toωη$ and $ωπ^0π^0$, the intermediate $ω(4S)$ and $ω(3D)$ should be introduced, which indicates that the enhancement structures around 2.2 GeV existing in $e^+e^-\toωη$ and $ωπ^0π^0$ contain the $ω(4S)$ and $ω(3D)$ signals. Nonetheless, in the process $e^+e^-\toωη$, the $ω(4S)$ plays a dominant role, while the $ω(4S)$ and $ω(3D)$ have similar sizable contributions in the process of $e^+e^-\toωπ^0π^0$, which leads to a difference in the line shape of enhancement structure in the cross sections under the interference effect. Thus, we find a solution to alleviate the puzzling difference of resonance parameter of two reported enhancement structures around 2.2 GeV existing in $e^+e^-\to ωη$ and $e^+e^-\toωπ^0π^0$ at BESIII. The present study provides valuable information to construct $ω$ meson family, which can be accessible at future experiment like BESIII.

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arXiv2022

Identifying the contribution of higher $ρ$ mesons around 2 GeV in the $e^+ e^- \to ωπ^0$ and $e^+ e^- \to ρη^{\prime}$ processes

The properties of the light vector meson states around 2.0 GeV have been poorly understood for a long time, which has become a barrier to the expansion to higher light vector meson spectrum. Recently, the BESIII collaboration released the measurements of the $e^+ e^- \to ωπ^0$ and $e^+ e^- \to ρη^{\prime}$ reactions above 2.0 GeV, both of which are ideal processes to study the isovector $ρ$ meson family. In this work, through carrying out a combined analysis of the Born cross section data for the above two processes with the theoretical support on mass spectrum, and production and strong decay behaviors of the $ρ$ meson family around 2.0 GeV, we identify the enhancement structure near 2034 MeV observed in $e^+e^-\toωπ^0$ to be the interference contribution from two resonances $ρ(1900)$ and $ρ(2150)$, and another enhancement structure at 2111 MeV reported in $e^+e^-\toρη^{\prime}$ to be the contributions from $ρ(2000)$ and $ρ(2150)$. This conclusion means that the $e^+e^-\toωπ^0$ and $e^+e^-\toρη^{\prime}$ are the excellent golden channels to establish $ρ(1900)$ and $ρ(2000)$, especially for a $D$-wave state $ρ(2000)$, whose experimental search in the $e^+e^-$ collision should be quite challenging. The relevant cross section measurements with higher precision are expected in the future BESIII and Belle II experiments.

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arXiv2021

Evidence supporting the existence of $P_c(4380)^{\pm}$ from the recent measurements of $B_s \to J/ψp\bar{p}$

Very recently, the LHCb collaboration released the newest measurements of $B_s \to J/ψp\bar{p}$, where an enhancement structure near 4.34 GeV was observed in the invariant mass spectrum of $J/ψp$ with the statistical significance of $3.1-3.7$ $σ$. In this work, by performing a combined analysis for the three invariant mass spectra of $B_s \to J/ψp\bar{p}$, we find that this $J/ψp$ structure near 4.34 GeV can correspond to the contributions from the $P_c(4380)^+$ state with the assumption of $J^{P}=3/2^{-}$ together with the reflections of $B_s \to (f_2^{*} \to p\bar{p})J/ψ$. Here, $P_c(4380)$ was first observed in $Λ_b \to J/ψp K$ but not confirmed in the updated LHCb data in 2019, and $f_2^{*}$ means the exciting light isoscalar tensor meson around 2.0 GeV. Thus, this provides a possible evidence to support the existence of the pentaquark $P_c(4380)$. Specifically, the assumed spin parity $J^{P}=3/2^{-}$ of $P_c(4380)$ is consistent with a prediction of the theoretical explanation of an $S$-wave $\bar{D}Σ_c^*$ molecular bound state.

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arXiv2021

Charmonium decays into $Λ_c\barΛ_c$ pair governed by the hadronic loop mechanism

In this work, we investigate the open-charm decay process $ψ\toΛ_c\barΛ_c$ via the hadronic loop mechanism for vector charmonia above $Λ_c\barΛ_c$ threshold. The branching ratios of these vector charmonium states to $Λ_c\barΛ_c$ are estimated. The charmonium explanation of the $Y(4630)$ observed in $e^+e^- \to Λ_c\barΛ_c$ is tested. Furthermore, for the predicted higher vector charmonia above 4.7 GeV, the branching ratios $\mathcal{B}[ψ(nS)\toΛ_c\barΛ_c]$ with $n=7,8,9$ are found to be of the order of magnitude of $10^{-4}-10^{-3}$ while $\mathcal{B}[ψ(mD)\toΛ_c\barΛ_c]$ with $m=6,7,8$ are of the order of magnitude of $10^{-3}-10^{-2}$. The experimental signals of these missing charmonium states are discussed. The search for them may be an interesting topic in the future BESIII and Belle II experiments.

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arXiv2021

Role of the newly measured $B\to KD\bar{D}$ process to establish $χ_{c0}(2P)$ state

In this work, the branching ratio $\mathcal{B}[B\to Kχ_{c0}(2P)]$ is extracted for the first time through the fit fractions in the newly measured $B\to KD\bar{D}$ process by LHCb. With the rescattering mechanism, this extracted branching ratio is reproduced well. Our study further enforces the role of the newly measured $B\to KD\bar{D}$ process to establish the $χ_{c0}(2P)$ charmonium state, which is a crucial step when constructing charmonium family.

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arXiv2021

Toward charged $Z_{cs}(3985)$ structure under a reflection mechanism

Very recently, the BESIII collaboration reported a charged hidden-charm structure with strangeness in the recoil mass of $K^+$ of a process $e^+e^-\to D_s^{*-}D^0K^+$ or $D_s^{-}D^{*0}K^+$, which is named as $Z_{cs}(3985)^{-}$. The newly observed charged structure can be treated as a partner structure with strangeness of well-known $Z_{c}(3885)^{-}$ reported in a process $e^+e^-\to D^{*-}D^0π^+$. In this work, we propose a novel picture to understand the nature of $Z_{cs}(3985)$. By performing a combined analysis for the line shape of the recoil mass distribution of $K^+$ at five energy points $\sqrt{s}=4.628, 4.641, 4.661, 4.681, 4.698$ GeV, we find that the $Z_{cs}(3985)$ can be explained as a reflection structure of charmed-strange meson $D_{s2}^{*}(2573)$, which is produced from the open-charm decay of $Y(4660)$ with a $D_s^*$ meson. Furthermore, we predicted the angular distribution of final state $D_s^{*-}$ in process $e^+e^-\to D_s^{*-}D^0K^+$ based on our proposed reaction mechanism, which may be an essential criterion to test the non-resonant nature of $Z_{cs}(3985)$ further.

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arXiv2021

Deciphering the light vector meson contribution to the cross sections of $e^+e^-$ annihilations into the open-strange channels through a combined analysis

In this work, we perform a combined analysis to the measured data of the cross section of open-strange processes $e^+e^- \to K^+K^-$, $e^+e^- \to K\bar{K}^{*}+c.c.$, $e^+e^- \to K^{*+}K^{*-}$, $e^+e^- \to K_1(1270)^+K^-$, $e^+e^- \to K_1(1400)^+K^-$, $e^+e^- \to K_2^{*}(1430)\bar{K}+c.c.$ and $e^+e^- \to K(1460)^+K^-$ with the support of study of hadron spectroscopy. We reveal the contribution of the possible light vector mesons around 2 GeV to reproduce the cross section data of the reported open-strange processes from $e^+e^-$ annihilation which may provide a new perspective to construct the light vector meson family and understand the $Y(2175)$.

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arXiv2021

Detecting the polarization in $χ_{cJ} \to ϕϕ$ decays to probe hadronic loop effect

In this work, we propose that detecting the polarization information of $χ_{cJ}\to ϕϕ~(J=0,1,2)$ can be as good test of the role of hadronic loop effect on these decays. Our results shows that the obtained ratios of helicity amplitudes are quite stable, which are $|F_{1,1}^{(0)}/F_{0,0}^{(0)}| \approx 0.359$, $|F_{1,0}^{(1)}/F_{0,1}^{(1)}| =1$, $|F_{1,1}^{(1)}/F_{0,1}^{(1)}| =0$, $|F^{(2)}_{1,0}|/|F^{(2)}_{0,0}|=|F^{(2)}_{0,1}|/|F^{(2)}_{0,0}| \approx 1.285,~|F^{(2)}_{1,-1}|/|F^{(2)}_{0,0}|=|F^{(2)}_{-1,1}|/|F^{(2)}_{0,0}| \approx 5.110$ and $|F^{(2)}_{-1,-1}|/|F^{(2)}_{0,0}|=|F^{(2)}_{1,1}|/|F^{(2)}_{0,0}| \approx 0.465$. By adopting these predicted ratios, we further generate Monte-Carlo events of moments $\langle t_{ij} \rangle$, which are directly related to the determination of helicity amplitudes. We suggest further experiments like BESIII and Belle II to perform an analysis on the polarizations of the $χ_{cJ}\to ϕϕ$ process in the future, which is important to understand the underlying decay mechanism existing in $χ_{cJ}$ decays.

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arXiv2021

Mapping a new cluster of charmoniumlike structures at $e^+e^-$ collisions

In this work, we find a Critical Energy induced Enhancement (CEE) mechanism for the general three-body open-charm process at the $e^+e^-$ collisions, which utilizes the peculiar kinematic behavior of the $e^+e^-$ annihilation process involving three-body final states. We present a general analysis of a three-body process $e^+e^-\to BC\to B(C\to DE)$. When the center-of-mass (CM) energy of the $e^+e^-$ collision satisfies a critical relation $\sqrt{s}=m_B+m_C$, there clearly exists the reflection peak of an intermediate $C$ state near the threshold of the invariant mass distribution of $m_{BE}$ or $m_{BD}$, whose formation is very sensitive to the CM energy. The reflection enhancement phenomenon induced at the critical energy means that a new cluster of charmoniumlike structures can be experimentally mapped. Taking an example of $e^+e^-\to D_s^{*-}D_{s2}^*(2573)^+ \to D_s^{*-}(D^0K^+)$, we further illustrate this novel phenomenon when $\sqrt{s}=4.680$ GeV. What is more important is that a series of optimal CM energy points to search for new charmoniumlike structures in three-body open-charm processes from $e^+e^-$ annihilation are suggested, which can be accessible at BESIII and further BelleII as a new research topic.

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arXiv2020

Fully-heavy structures in the invariant mass spectrum of $J/ψψ(3686)$, $J/ψψ(3770)$, $ψ(3686) ψ(3686)$, and $J/ψΥ(1S)$ at hadron colliders

Motivated by a recent successful dynamical explanation for the newly observed fully-charm structure $X(6900)$ in the mass spectrum of di-$J/ψ$ by LHCb [J.~Z.~Wang \textit{et al.} arXiv:2008.07430], in this work, we extend the same dynamical rescattering mechanism to predict the line shape of more potential fully-heavy structures in the invariant mass spectrum of $J/ψψ(3686)$, $J/ψψ(3770)$, $ψ(3686) ψ(3686)$, and $J/ψΥ(1S)$ at high energy proton-proton collisions, whose verification in experiments should be helpful to further clarify the nature of $X(6900)$. The above final states of vector heavy quarkonia can be experimentally reconstructed more effectively by a $μ^+μ^-$ pair in the muon detector compared with $Q\bar{Q}$ meson with other quantum numbers. Furthermore, the corresponding peak mass positions of each of predicted fully-heavy structures are also given. Our theoretical studies here could provide some valuable information for the future measurement proposals of LHCb and CMS, especially based on the accumulated data after completing Run III of LHC in the near future.

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arXiv2020

Universal non-resonant explanation to charmoniumlike structures $Z_c(3885)$ and $Z_c(4025)$

Different from the usual tetraquark assignment to charged $Z_c(3885)$ and $Z_c(4025)$ charmoniumlike structures, in this letter we propose a universal non-resonant explanation to decode these $Z_c$'s, which is based on a special dynamical behavior of $e^+e^-\to D^{(*)}\bar{D}^*π$. Our study shows that $Z_c(3885)$ and $Z_c(4025)$ are only the reflection from the $P$-wave charmed meson $D_1(2420)$ involved in $e^+e^-\to D^{(*)}\bar{D}^*π$. Obviously, the present work provides a unique perspective, which can be examined by future experiments like BESIII and BelleII.

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arXiv2020

Producing fully-charm structures in the $J/ψ$-pair invariant mass spectrum

Very recently, the LHCb Collaboration reported the observation of several enhancements in the invariant mass spectrum of a $J/ψ$ pair between 6.2 and 7.4 GeV. In this work, we propose the dynamical mechanism to mimic the experimental data of a di-$J/ψ$ mass spectrum given by LHCb, which is based on the reactions, where all the possible combinations of a double charmonium directly produced by a proton-proton collision are transferred into a final state $J/ψJ/ψ$. We find that the LHCb experimental data can be well reproduced. We further extend our framework to study a di-$Υ(1S)$ system, and give the line shape of a differential cross section of a partner process in a $b\bar{b}$ system on the invariant mass of $Υ(1S)Υ(1S)$, which shows that there should exist possible enhancements near $m_{Υ(1S)Υ(1S)}=$19.0, 19.3, 19.7 GeV in the $Υ(1S)$-pair invariant mass spectrum. These predictions can be tested in LHCb and CMS, which can be as a potential research issue in near future.

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arXiv2020

Toward $e^+e^-\to π^+π^-$ annihilation inspired by higher $ρ$ mesonic states around 2.2 GeV

Very recently, the {\it BABAR} Collaboration indicated that there exist an explicit enhancement structure near 2.2 GeV when focusing on the $e^+e^-\toπ^+π^-$ process again, which inspires our interest in studying the production of higher $ρ$ mesonic states. Since the branching ratio of $π^+π^-$ channel of $D-$wave $ρ$ states are much smaller than $S-$wave states, we choose $ρ(1900)$ and $ρ(2150)$ as the intermediate states in $e^+e^-\toπ^+π^-$, where $ρ(1900)$ and $ρ(2150)$ are treated as $ρ(3S)$ and $ρ(4S)$ states, respectively. Our result indicates that the $BABAR$'s data of $e^+e^-\toπ^+π^-$ around 2 GeV can be depicted well, which shows that this enhancement structure near 2.2 GeV existing in $e^+e^-\toπ^+π^-$ can be due to the contribution from two $ρ$ mesons, $ρ(1900)$ and $ρ(2150)$. Additionally, this conclusion can be enforced by the consistence of the extracted values of $Γ_{e^+e^-}\mathcal{B}(π^+π^-)$ of $ρ(1900)$ and $ρ(2150)$ in the whole fitting processes and the corresponding theoretical calculations. The present study of $e^+e^-\toπ^+π^-$ data may provide valuable information to establish the $ρ$ meson family.

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arXiv2020

Role of the low-lying nucleon resonances in the $p\bar{p} \to ψη$ reaction

Within the effective Lagrangian approach, we study the $p\bar{p} \rightarrow ψη$ [$ψ\equivψ(3686)$, $J/ψ$] reaction at the low energy where the contributions from nucleon pole and low-lying nucleon resonances, $N(1520)$, $N(1535)$ and $N(1650)$ are considered. All the model parameters are determined with the help of current experimental data on the decay of $ψ\to p \bar{p} η$. Within the model parameters, the total and differential cross sections of the $p\bar{p} \rightarrow ψη$ reaction are predicted. We show that the relative phases between different amplitudes of different nucleon resonance will change significantly the angular distributions of the $\bar{p} p \to ψη$ reaction. Therefore, we conclude that these reactions are suitable to study experimentally the properties of the low-lying nucleon resonance and the reaction mechanisms. We hope that these theoretical calculations can be tested by future experiments.

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