Search

In this work, we investigate the $\Upsilon(10753)\to\Upsilon(nS)\pi^+\pi^-$ ($n=1,2,3$) processes by considering the hadronic loop mechanism, where $\Upsilon(10753)$ is assigned to a conventional bottomonium in the $4S$-$3D$ mixing scheme. Our results of the concerned processes own considerable branching ratios, which can reach up to the order of magnitude of $10^{-4}-10^{-3}$. We should indicate that the measured $\Gamma_{e^+e^-}\times\mathcal{B}[\Upsilon(10753)\to\Upsilon(nS)\pi^+\pi^-]$ values given by Belle can be reproduced well. This fact supports the former bottomonium assignment to the $\Upsilon(10753)$ in the $4S$-$3D$ mixing scheme. Obviously, it is a good opportunity for the ongoing Belle II experiment if the predicted result in this work can be tested further., Comment: 7 pages, 4 figures and 1 table. arXiv admin note: text overlap with arXiv:2106.14123

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 $e^+ e^- \to \omega\pi^0$ and $e^+ e^- \to \rho\eta^{\prime}$ reactions above 2.0 GeV, both of which are ideal processes to study the isovector $\rho$ 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 $\rho$ meson family around 2.0 GeV, we identify the enhancement structure near 2034 MeV observed in $e^+e^-\to\omega\pi^0$ to be the interference contribution from two resonances $\rho(1900)$ and $\rho(2150)$, and another enhancement structure at 2111 MeV reported in $e^+e^-\to\rho\eta^{\prime}$ to be the contributions from $\rho(2000)$ and $\rho(2150)$. This conclusion means that the $e^+e^-\to\omega\pi^0$ and $e^+e^-\to\rho \eta^{\prime}$ are the excellent golden channels to establish $\rho(1900)$ and $\rho(2000)$, especially for a $D$-wave state $\rho(2000)$, 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., Comment: 8 pages, 4 figures and 3 tables

Very recently, the LHCb collaboration released the newest measurements of $B_s \to J/\psi p\bar{p}$, where an enhancement structure near 4.34 GeV was observed in the invariant mass spectrum of $J/\psi p$ with the statistical significance of $3.1-3.7$ $\sigma$. In this work, by performing a combined analysis for the three invariant mass spectra of $B_s \to J/\psi p\bar{p}$, we find that this $J/\psi p$ 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 $B_s \to (f_2^{*} \to p\bar{p})J/\psi$. Here, $P_c(4380)$ was first observed in $\Lambda_b \to J/\psi p K$ 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 $\bar{D}\Sigma_c^*$ molecular bound state., Comment: 8 pages, 2 tables and 3 figures, accepted by Physical Review D

We study the so-called magic mixing angles for doubly heavy baryons. Defining that a magic mixing angle rotates states with definite $^{2S+1}(l_\lambda)_J$ to make them heavy-quark symmetric states, we derive the magic mixing angle only in the case $L_\rho=0$ between the heavy quark symmetric states with quantum numbers $\left(J, j_\ell\right)$ and the states with $\left(J, s_q+j_\rho\right)=\left(J, \{^4l_\lambda/^2l_\lambda\}\right)$ for a doubly heavy baryon in the standard $\rho-\lambda$ configuration, where $\vec j_\ell=\vec l_\lambda+\vec s_q$, $\vec s_\rho=\vec s_{Q1}+\vec s_{Q2}$, and $\vec j_\rho=\vec s_\rho+\vec L_\rho$. We discuss how this mixing angle affects model building for a doubly heavy baryon., Comment: 6 pages, 1 figure

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 $Y(2175)$., Comment: 12 pages, 2 figures and 6 tables

In this work, we investigate the open-charm decay process $\psi\to\Lambda_c\bar{\Lambda}_c$ via the hadronic loop mechanism for vector charmonia above $\Lambda_c\bar{\Lambda}_c$ threshold. The branching ratios of these vector charmonium states to $\Lambda_c\bar{\Lambda}_c$ are estimated. The charmonium explanation of the $Y(4630)$ observed in $e^+e^- \to \Lambda_c\bar{\Lambda}_c$ is tested. Furthermore, for the predicted higher vector charmonia above 4.7 GeV, the branching ratios $\mathcal{B}[\psi(nS)\to\Lambda_c\bar{\Lambda}_c]$ with $n=7,8,9$ are found to be of the order of magnitude of $10^{-4}-10^{-3}$ while $\mathcal{B}[\psi(mD)\to\Lambda_c\bar{\Lambda}_c]$ 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., Comment: 8 pages, 6 figures and 4 tables. Accepted by Phys. Rev. D

In a molecular scenario, we investigate the isospin-breaking hidden charm decay processes of $X(3872)$, i.e., $X(3872) \to \pi^+ \pi^- J/\psi$, $X(3872) \to \pi^+ \pi^- \pi^0 J/\psi$, and $X(3872)\to \pi^0\chi_{cJ}$. We assume that the source of the strong isospin violation comes from the different coupling strengths of $X(3872)$ to its charged components $D^{\ast +} D^-$ and neutral components $D^{\ast 0 } \bar{D}^0$ as well as the interference between the charged meson loops and neutral meson loops. The former effect could fix our parameters by using the measurement of the ratio $\Gamma[X(3872) \to \pi^+ \pi^- \pi^0 J/\psi]/\Gamma[X(3872) \to \pi^+ \pi^- J/\psi]$. With the determined parameter range, we find that the estimated ratio $\Gamma[X(3872) \to \pi^0 \chi_{c1}/\Gamma[X(3872) \to \pi^+ \pi^- J/\psi]$ is well consistent with the experimental measurement from the BESIII collaboration. Moreover, the partial width ratio of $\pi^0 \chi_{cJ}$ for $J=0,1,2$ is estimated to be $1.77\sim1.65:1:1.09\sim1.43$, which could be tested by further precise measurements of BESIII and Belle II., Comment: 11 pages, 7 figures, accepted for publication in the Eur.Phys.J.C

By an unquenched quark model, we predict a charmed-strange baryon state, namely, the $\Omega_{c0}^d(1P,1/2^-)$. Its mass is predicted to be 2945 MeV, which is below the $\Xi_c\bar{K}$ threshold due to the nontrivial coupled-channel effect. So the $\Omega_{c0}^d(1P,1/2^-)$ state could be regraded as the analog of the charmed-strange meson $D_{s0}^*(2317)$. It is a good opportunity for the running Belle II experiment to search for this state in the $\Omega_c^{(*)}\gamma$ mass spectrum experiment in the future., Comment: 8 pages, 2 tables and 3 figures. Accepted by PRD

Motivated by a recent successful dynamical explanation for the newly observed fully-charm structure $X(6900)$ in the mass spectrum of di-$J/\psi$ 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 $J/\psi \psi(3686)$, $J/\psi \psi(3770)$, $\psi(3686) \psi(3686)$, and $J/\psi \Upsilon(1S)$ 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 $\mu^+\mu^-$ 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., Comment: 7 pages, 5 figures and 2 tables

In the present work, we investigate the dipion transitions between $\Upsilon(5S)$ and $\Upsilon_J(1D)$ with $J=1, 2, 3$. Our analysis indicates that the dominant sources of the anomalously large widths of $\Upsilon(5S)\to \Upsilon_J(1D) \pi^+ \pi^-$ should be $Z_b^{(\prime)}$, i.e., the dipion transitions occur via the cascade decays $\Upsilon(5S)\to Z_b^{(\prime)\pm} \pi^\mp \to \Upsilon_J(1D) \pi^+ \pi^-$. With the assumption that all the short ranged dynamics could be absorbed in a single cutoff with a model parameter $\alpha$, the present estimations indicate that in a reasonable parameter range the measured branching ratios of $\Upsilon(5S) \to \Upsilon_J(1D) \pi^+ \pi^-$ can be reproduced in magnitude, which further proves that the decays via $Z_b^{(\prime)}$ dominate the dipion transitions of $\Upsilon(5S)$ to $\Upsilon_J(1D)$. Moreover, we also predict the ratios of the branching fractions of $Z_b^{(\prime)} \to \Upsilon_J(1D) \pi$, which in our calculations are largely independent of the parameter $\alpha$ and could be tested by further experiments in Belle II., Comment: 9 pages, 5 figures, accepted for publication in the Phys.Rev.D

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 $e^+e^-\to D^{*-}D^0\pi^+$. 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., Comment: 5 pages, 1 table and 3 figures

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., Comment: 6 pages, 1 table and 5 figures. Accepted by Phys. Lett. B

Very recently, the LHCb Collaboration reported the observation of several enhancements in the invariant mass spectrum of a $J/\psi$ pair between 6.2 and 7.4 GeV. In this work, we propose the dynamical mechanism to mimic the experimental data of a di-$J/\psi$ 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 $J/\psi J/\psi$. We find that the LHCb experimental data can be well reproduced. We further extend our framework to study a di-$\Upsilon(1S)$ 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 $\Upsilon(1S)\Upsilon(1S)$, which shows that there should exist possible enhancements near $m_{\Upsilon(1S)\Upsilon(1S)}=$19.0, 19.3, 19.7 GeV in the $\Upsilon(1S)$-pair invariant mass spectrum. These predictions can be tested in LHCb and CMS, which can be as a potential research issue in near future., Comment: 5 pages, 1 table and 2 figures

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 $e^+e^-\to D^{(*)}\bar{D}^*\pi$. 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 $e^+e^-\to D^{(*)}\bar{D}^*\pi$. Obviously, the present work provides a unique perspective, which can be examined by future experiments like BESIII and BelleII., Comment: 5 pages, 4 figures and 1 table. Accepted by Eur. Phys. J. C

Experimentally observed excited strange charmed mesons $D_{s0}^*(2317)^{\pm}$, $D_{s1}(2460)^{\pm}$, $D_{s1}(2536)^{\pm}$, $D_{s2}^*(2573)^{\pm}$, $D_{s1}^*(2700)^{\pm}$, $D_{s1}^*(2860)^{\pm}$, $D_{s3}^*(2860)^{\pm}$, and $D_{sJ}(3040)^{\pm}$ are identified tentatively according to their spin, parity, and masses. Using the heavy quark effective theory in the leading order approximation, we study their strong decays to ground state charmed mesons plus light pseudoscalar mesons. The branching ratios are classified, $(D_{s0}^*(2317), D_{s1}(2460))$ as $(1^3P_0, 1P_1)$ and $(D_{s1}(2536), D_{s2}^*(2573))$ as $(1P_1^{\prime}, 1^3P_2)$, in heavy quark doublets. The $D_{s1}^*(2700)$ as $2^3S_1$ and its spin partner, $2^1S_0$ is still missing in the experiment. Its strong decay behavior is predicted. The assignment of $D_{sJ}^*(2860)$ as four resonance states $D_{s1}^*(2860)$, $D_{s2}^*(2860)$, $D_{s2}^{*\prime}(2860)$, $D_{s3}^*(2860)$ is favored, where for $D_{s3}^*(2860)^{\pm}$ the mass should be expected to higher than 2.86 GeV. The $D_{sJ}(3040)$ is more likely to be 2$P_1$ state. We construct the Regge trajectories of experimentally observed strange charmed mesons in $(M^2, J)$ and $(M^2, n_r)$ planes, which estimate the masses of $1^3D_3$, $1^3F_4$, $1D_2$, $1^1F_3$, $1D_2^{\prime}$, $1F_3^{\prime}$, $3^3S_1$, and $3P_1$ states with fixing the slopes and intercepts of the Regge lines. Moreover, the strong decay rates and the branching ratios of these higher excited states are also examined, which distinguished the dominant decay channels for these higher excited states. Our results could provide some important clues in LHCb, BESIII, KEK-B, and the forthcoming Belle II and $\overline{\mbox{\sffamily P}}${\sffamily ANDA} experiments., Comment: 14 pages

In this work, we seriously discuss whether $X(3915)$ can be treated as a $\chi_{c0}(2P)$ state. Based on an unquenched quark model, we give the mass spectrum of the $\chi_{cJ}(2P)$ states, where there are no free input parameters in our calculation. Our result shows that the mass gap between $\chi_{c0}(2P)$ and $\chi_{c2}(2P)$ can reach 13 MeV, which can reproduce the mass difference between $Z(3930)$ and $X(3915)$. Additionally, the calculated masses of $\chi_{c0}(2P)$ and $\chi_{c2}(2P)$ are consistent with experimental values of $X(3915)$ and $Z(3930)$, respectively. Besides, giving the mass spectrum analysis to support $X(3915)$ as $\chi_{c0}(2P)$, we also calculate the width of $\chi_{c0}(2P)$ with the same framework, which is also consistent with the experimental data of $X(3915)$. Thus, the possibility of charmoniumlike state $X(3915)$ as $\chi_{c0}(2P)$ state is further enforced., Comment: 12 pages, 9 figures and 6 tables. More discussions added. Accepted by PRD for publication

In this work, we present the mass spectrum of higher charomona around and above 4.6 GeV by adopting the unquenched potential model. We perform a combined fit to the updated experimental data of $e^+e^- \to \psi(2S)\pi^+\pi^-$ and $e^+e^-\to \Lambda_c\bar{\Lambda}_c$. To understand the "platform" structure observed in the range of $4.57 \sim 4.60$ GeV existing in the $\Lambda_c\bar{\Lambda}_c$ invariant mass spectrum of $e^+e^-\to \Lambda_c\bar{\Lambda}_c$ of BESIII, we introduce two resonances in this combined fit to the $e^+e^- \to \psi(2S)\pi^+\pi^-$ and $e^+e^-\to \Lambda_c\bar{\Lambda}_c$, which have resonance parameters, $m_{Y_1}=4585\pm2$ MeV, $\Gamma_{Y_1}=29.8\pm8.0$ MeV, $m_{Y_2}=4676\pm7$ MeV, and $\Gamma_{Y_2}=85.7\pm15.0$ MeV. Furthermore, combining with our theoretical results, we indicate that the two charmonium-like $Y$ states can be due to two higher charmonia, which are mixtures of $6S$ and $5D$ $c\bar{c}$ states. Their two-body open-charm decay behaviors are given. Under the same framework, our analysis of the data of $e^+e^-\to D_{s}^+D_{s1}(2536)^-$ recently released by Belle supports to introduce these two higher charmonia around 4.6 GeV. Additionally, we predict the masses and two-body open-charm decays of six higher charmonia $\psi(nS)$ and $\psi(mD)$ with $n=7,8,9$ and $m=6,7,8$ above 4.6 GeV. Search for these higher charmonia will be an interesting issue for the running BESIII and BelleII, and even the possible Super Tau-Charm Factory discussed in China., Comment: 11 pages, 4 tables and 8 figures. More discussions and references added. Accepted by Phys. Rev. D

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., Comment: 9 pages, 13 figures, arcticle accepted for publication in the Phys.Rev.D

The measured masses and strong decays of $\Lambda_b(6146)^0$ and $\Lambda_b(6152)^0$ required us to decode them as the 1$D$ excited states with $J^P=3/2^+$ and $J^P=5/2^+$, respectively. Under the suggested assignment, the masses and total decay widths of $\Lambda_b(6146)^0$ and $\Lambda_b(6152)^0$ can be explained. As a $J^P=3/2^+$ state, the $\Lambda_b(6146)^0$ should mainly decay into $\Sigma_b(5815)\pi$. However, this theoretical result is in contradiction to the measurement since no significant $\Lambda_b(6146)^0\rightarrow\Sigma_b(5815)^\pm\pi^\mp$ signals were observed by the LHCb. The possible explanations to this difficulty are mentioned. For completeness, we present the prediction of masses and decay widths of other unseen 1$D$ bottom baryons in this work. Our results could provide some important clues for the upcoming experiments., Comment: 8 pages, 3 figures, 8 tables, matches published version

In 2017, the BESIII Collaboration announced the observation of a charged charmonium-like structure in the $\psi(3686)\pi^\pm$ invariant mass spectrum of the $e^+ e^- \to \psi(3686) \pi^+ \pi^-$ 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 $e^+ e^- \to \psi(3686) \pi^+ \pi^-$, and the corresponding $\psi(3686)\pi^\pm$ and dipion invariant mass spectra. Our result shows that the observed charged charmonium-like structure in $e^+ e^- \to \psi(3686) \pi^+ \pi^-$ 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., Comment: 11 pages, 8 figures and 4 tables

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 $J/\psi$ 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 $\psi(4380)$, whose evidence is found by analyzing the $e^+e^-\to \psi(3686)\pi^+\pi^-$ data from BESIII. If $Y(4220)$ is indeed a charmonium, we must face how to settle the established charmonium $\psi(4415)$ in the $J/\psi$ 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 $\psi(4415)$, which do not contradict the present experimental data. Additionally, we predict a charmonium partner $\psi(4500)$ of $\psi(4415)$, 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., Comment: 15 pages, 10 figures and 4 tables. Accepted by Phys. Rev. D

Starting from the semirelativistic Hamiltonian for a doubly heavy baryon system ($QQq$) with Coulomb and linear confining scalar potentials, and operating the naive Foldy-Wouthuysen-Tani transformation on two heavy quarks, I construct a formulation how to calculate mass spectra and wave functions of doubly heavy baryons. Based on our formulation, their masses and wave functions are expanded in $1/m_Q$ with a heavy quark mass $m_Q$ and the $\lambda$ mode lowest-order equation is examined carefully to obtain a complete set of eigenfunctions. I claim that the $\rho$ mode wave function should be given by other nonrelativistic methods, e.g., the Godfrey-Isgur model to give a complete wave function for a doubly heavy baryon., Comment: 4 pages, 1 figure, a talk at the 8th International Conference on Quarks and Nuclear Physics

Recently, the BESIII Collaboration reported a new measurement of the $\eta_c \rho$ 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.

In this work, we propose a possible experimental research topic on the $\Upsilon(6S)\to \Upsilon(nS)\eta^{(\prime)}$ ($n=1,2,3$) transitions. Considering the hadronic loop effect from the intermediate $S$-wave $B_{(s)}$ and $B_{(s)}^*$ mesons, we estimate the partial decay widths and the corresponding branching ratios of the $\Upsilon(6S)\to \Upsilon(nS)\eta^{(\prime)}$ hadronic decays, which become considerably large. With the running of the Belle II experiment, it becomes possible to explore these $\Upsilon(6S)\to \Upsilon(nS)\eta^{(\prime)}$ transitions., Comment: 6 pages and 3 figures. Accepted by Phys. Rev. D

We perform the investigation of two-body hidden-bottom transitions of the $\Upsilon(6S)$, which include $\Upsilon(6S) \to \Upsilon(1^3D_J) \eta~~(J=1,2,3)$ decays. For estimating the branching ratios of these processes, we consider contributions from the triangle hadronic loops composed of S-wave $B_{(s)}$ and $B_{(s)}^*$ mesons, which are a bridge to connect the $\Upsilon(6S)$ and final states. Our results show that both of the branching ratios of these decays can reach $10^{-3}$. Due to such considerable potential to observe these two-body hidden-bottom transitions of the $\Upsilon(6S)$, we suggest the forthcoming Belle II experiment to explore them., Comment: 7 pages, 3 figures and 1 table

In this work, we study higher bottomonia up to the $nL=8S$, $6P$, $5D$, $4F$, $3G$ multiplets using the modified Godfrey-Isgur (GI) model, which takes account of color screening effects. The calculated mass spectra of bottomonium states are in reasonable agreement with the present experimental data. Based on spectroscopy, partial widths of all allowed radiative transitions, annihilation decays, hadronic transitions, and open-bottom strong decays of each state are also evaluated by applying our numerical wave functions. Comparing our results with the former results, we point out difference among various models and derive new conclusions obtained in this paper. Notably, we find a significant difference between our model and the GI model when we study $D, F$, and $G$ and $n\ge 4$ states. Our theoretical results are valuable to search for more bottomonia in experiments, such as LHCb, and forthcoming Belle II., Comment: 40 pages, 4 figures and 40 tables. Accepted by Eur. Phys. J. C

Using the Regge-like formula $(M-m_Q)^2=\pi\sigma L$ between hadron mass $M$ and angular momentum $L$ with a heavy quark mass $m_Q$ and a string tension $\sigma$, we analyze all the heavy-light systems, i.e., $D/D_s/B/B_s$ mesons and charmed and bottom baryons.Numerical plots are obtained for all the heavy-light mesons of experimental data whose slope becomes nearly equal to 1/2 of that for light hadrons. Assuming that charmed and bottom baryons consist of one heavy quark and one light cluster of two light quarks (diquark), we apply the formula to all the heavy-light baryons including recently discovered $\Omega_c$'s and find that these baryons experimentally measured satisfy the above formula. We predict the average mass values of $B$, $B_s$, $\Lambda_b$, $\Sigma_c$, $\Xi_c$, and $\Omega_c$ with $L=2$ as 6.01, 6.13, 6.15, 3.05, 3.07, and 3.34 GeV, respectively. Our results on baryons suggest that these baryons can be safely regarded as heavy quark-light cluster configuration. We also find a universal description for all the heavy-light mesons as well as baryons, i.e., one unique line is enough to describe both of charmed and bottom heavy-light systems. Our results suggest that instead of mass itself, gluon flux energy is essential to obtain a linear trajectory., Comment: 10 pages, 8 figures, 5 tables

In this letter, we decode the newly observed charmoniumlike states, $Y(4320)$ and $Y(4390)$, by introducing interference effect between $\psi(4160)$ and $\psi(4415)$, 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 $\psi(4160)$ and $\psi(4415)$ are missing in the cross sections of $e^+e^- \to \pi^+ \pi^- J/\psi$ and $\pi^+ \pi^- h_c$ 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 $e^+e^- \to D^0 \pi^+ D^{\ast-}$, which provides an extra support to $\psi(4S)$ 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., Comment: 5 pages, 4 figures

In this work, using the covariant light front approach with conventional vertex functions, we estimate the production rates of $D$-wave charmed/charmed-strange mesons via $B_{(s)}$ semileptonic decays. Due to these calculated considerable production rates, it is possible to experimentally search for $D$-wave charmed/charmed-strange mesons via the semileptonic decays, which may provide extra approach to explore $D$-wave charmed/charmed-strange mesons., Comment: 25 pages, 6 figures and 4 tables

The mass spectrum of the kaon family is analyzed by the {modified} Godfrey-Isgur model with a color screening effect approximating the kaon as a heavy-light meson system. This analysis gives us the structure and possible assignments of the observed kaon candidates, which can be tested by comparing the theoretical results of their two-body strong decays with the experimental data. Additionally, prediction of some partial decay widths is made on the kaons still missing in experiment. This study is crucial to establishing the kaon family and searching for their higher excitations in the future., Comment: 19 pages, 7 figures, and 17 tables. More discussions added and typos corrected. Accepted by Eur. Phys. J. C

In this work, we investigate the hadronic loop contributions to the $\Upsilon(6S) \to \chi_{bJ} \phi~(J=0,1,2)$ along with $\Upsilon(6S) \to \chi_{bJ} \omega~(J=0,1,2)$ transitions. We predict that the branching ratios of $\Upsilon(6S) \to \chi_{b0} \phi$, $\Upsilon(6S) \to \chi_{b1} \phi$ and $\Upsilon(6S) \to \chi_{b2} \phi$ 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 $\Upsilon(6S) \to \chi_{b0} \omega$, $\Upsilon(6S) \to \chi_{b1} \omega$ and $\Upsilon(6S) \to \chi_{b2} \omega$ 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 $\Upsilon(6S)\to \chi_{bJ}\phi$ transitions, $\mathcal{R}^\phi_{10}={\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \phi]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \phi]} \approx 0.74$, $\mathcal{R}^\phi_{20}= {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \phi]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \phi]} \approx 3.28$, and $\mathcal{R}^\phi_{21} = {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \phi]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \phi]} \approx 4.43$, and for $\Upsilon(6S)\to \chi_{bJ}\omega$ transitions, $\mathcal{R}^\omega_{10}={\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \omega]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \omega]} \approx 4.11$, $\mathcal{R}^\omega_{20}= {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \omega]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b0} \omega]} \approx 7.06$, and $\mathcal{R}^\omega_{21} = {\mathcal{B}[\Upsilon(6S) \to \chi_{b2} \omega]}/{\mathcal{B}[\Upsilon(6S) \to \chi_{b1} \omega]} \approx 1.72$. With the running of BelleII in the near future, experimental measurement of these two kinds of transitions will be a potential research issue., Comment: 10 pages, 10 figures and 1 table. Accepted by Eur. Phys. J. C

An approximate rotational symmetry of a heavy-light meson is viewed from a string picture. Using a simple string configuration, we derive a formula, $(M-m_c)^2=\pi\sigma L$, whose coefficient of the r.h.s. is just 1/2 of that of a light meson with two light quarks. A numerical plot is obtained for $D$ mesons of experimental data as well as several theoretical models, which shows good agreement with this formula., Comment: 4 pages, 5 figures, talk at XII Quark Confinement and the Hadron Spectrum

There is a puzzle in the $\Lambda_c^+$ family, i.e., one member with $J^P=3/2^+$ is missing in a $L=2$ multiplet which the heavy quark effective theory predicts, and $J^P$'s of $\Lambda_c(2765)^+$ and $\Lambda_c(2940)^+$ are unknown. Using a light diquark picture to calculate baryon masses, we study possible assignments of two $\Lambda_c$'s with unknown $J^P$ and the missing $\Lambda_c^+$ with $3/2^+$ for $L=2$, and we find the most probable possibility that the peak corresponding to $\Lambda_c(2880)^+$ actually includes a missing member with spin $3/2^+$ for $L=2$ and that quantum numbers of $\Lambda_c(2765)^+$ and $\Lambda_c(2940)^+$ are $2S(1/2^+)$ and $2P(1/2^-)$, respectively., Comment: 3 pages, 3 tables

In this work, we systematically study the mass spectra and strong decays of $1P$ and $2S$ charmed and charmed-strange baryons in the framework of nonrelativistic constituent quark models. With the light quark cluster-heavy quark picture, the masses are simply calculated by a potential model. The strong decays are studied by the Eichten-Hill-Quigg decay formula. Masses and decay properties of the well-established $1S$ and $1P$ states can be reproduced by our method. $\Sigma_c(2800)^{0,+,++}$ can be assigned as a $\Sigma_{c2}(3/2^-)$ or $\Sigma_{c2}(5/2^-)$ state. We prefer to interpret the signal $\Sigma_c(2850)^0$ as a $2S(1/2^+)$ state although at present we cannot thoroughly exclude the possibility that this is the same state as $\Sigma_c(2800)^0$. $\Lambda_c(2765)^+$ or $\Sigma_c(2765)^+$ could be explained as the $\Lambda_c^+(2S)$ state or $\Sigma^+_{c1}(1/2^-)$ state, respectively. We propose to measure the branching ratio of $\mathcal{B}(\Sigma_c(2455)\pi)/\mathcal{B}(\Sigma_c(2520)\pi)$ in future, which may disentangle the puzzle of this state. Our results support $\Xi_c(2980)^{0,+}$ as the first radial excited state of $\Xi_c(2470)^{0,+}$ with $J^P=1/2^+$. The assignment of $\Xi_c(2930)^0$ is analogous to $\Sigma_c(2800)^{0,+,++}$, \emph{i.e.}, a $\Xi^\prime_{c2}(3/2^-)$ or $\Xi^\prime_{c2}(5/2^-)$ state. In addition, we predict some typical ratios among partial decay widths, which are valuable for experimental search for these missing charmed and charmed-strange baryons., Comment: 16 pages, 3 figures, 13 tables. Accepted by Eur. Phys. J. C

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., Comment: 7 pages, 4 figures, 3 tables, minor revision, accepted by Phys. Rev. D

We study the observed $B^-\rightarrow X(3823)K^-$ decay via rescattering mechanism and show that this branching ratio is well reproduced by this mechanism. We further extend this theoretical framework to investigate the decays of $B^-\to\eta_{c2} (^1D_2)/\psi_3(^3D_3)K^-$, where the $\eta_{c2} (^1D_2)$ and the $\psi_3(^3D_3)$ are $D$-wave charmonium partners of the $X(3823)$. Our results show that the branching ratios, $B^-\to \eta_{c2}(^1D_2) K^-$ and $B^-\to \psi_3(^3D_3) K^-$, are of the order of $10^{-5}$, which can be accessible at LHCb, Belle and forthcoming BelleII., Comment: 9 pages, 2 figures. Accepted by Phys. Rev. D

Careful observation of the experimental spectra of heavy-light mesons tells us that heavy-light mesons with the same angular momentum $L$ are almost degenerate. The estimate is given how much this degeneracy is broken in our relativistic potential model, and it is analytically shown that expectation values of a commutator between the lowest order Hamiltonian and ${\vec L}^{~2}$ are of the order of $1/m_Q$ with a heavy quark mass $m_Q$. It turns out that nonrelativistic approximation of heavy quark system has a rotational symmetry and hence degeneracy among states with the same $L$. This feature can be tested by measuring higher orbitally and radially excited heavy-light meson spectra for $D/D_s/B/B_s$ in LHCb and forthcoming BelleII., Comment: 4 pages, 1 table

A detailed analysis to find a missing $\psi(4S)$ is made by utilizing the recent precise mesurements of the cross section for the process $e^+e^-\to \psi(2S)\pi^+\pi^-$ by Belle. Assuming three resonances $Y(4360)$, $Y(4660)$, and $\psi(4S)$ to fit the data, we obtain the resonance parameters for $\psi(4S)$ as $m=4243$ MeV and $\Gamma=16 \pm 31$ MeV showing a narrow state as predicted before. A combined fit to the data $e^+ e^- \to \psi(2S) \pi^+ \pi^-, \ h_c \pi^+ \pi^-$, and $\chi_{c0} \omega$ is also performed to obtain the similar resonance parameters of $\psi(4S)$. The upper limit of the branching ratio is fitted to be $\mathcal{B}(\psi(4S)\to\psi(2S)\pi^+\pi^-) < 3\times 10^{-3}$, which can be understood by hadronic loop contributions in reasonable parameters range. In addition, the ratios of the branching ratios of the $\psi(4S)$ dipion transition to the one of $\psi(4S)\to\chi_{c0}\omega$ are fitted, which can be further measured by BESIII and forthcoming BelleII to confirm the existence of $\psi(4S)$., Comment: 9 pages, 10 figures

In this work, we study the high-spin states with masses below 3 GeV observed in experiments and we perform analysis of mass spectrum and investigation of strong decay behaviors of the high-spin states. Comparing our results with the experimental data, we can reveal the underlying properties of these high-spin states; more importantly, we also predict their abundant decay features, which can provide valuable information for experimental exploration of these high-spin states., Comment: 17 pages, 15 figures and 4 tables. More discussions added. Accepted by Phys. Rev. D

Considering abundant experimental information of charmed mesons and the present research status, in this work we systematically study higher radial and orbital excitations in the charmed meson family by analyzing the mass spectrum and calculating their two-body OZI-allowed decay behaviors. This phenomenological analysis not only reveals underlying propertes of the newly observed charmed states $D(2550)$, $D^*(2600)$, $D^*(2760)$, $D(2750)$, $D_J(2580)$, $D^*_J(2650)$, $D^*_J(2760)$, $D_J(2740)$, $D_J(3000)$ and $D^*_J(3000)$, but also provides valuable information of the charmed mesons still missing in experiments., Comment: 15 pages, 7 tables and 5 figures. More discussions and references added. Accepted by Phys. Rev. D

This paper summarizes what we have done so far to explain charged charmonium/bottomonium-like structures using a hadronic triangle diagram which we call the initial single chiral particle emission mechanism. We discuss processes like $A\to A'+P+P'$ in which two chiral particles $P$ and $P'$ are emitted from $A$. In the intermediate we consider a hadronic one-loop diagram in which $D^{(*)}/D_s^{(*)}/B^{(*)}/B_s^{(*)}$ are included to explain some enhancements experimentally observed. Using this mechanism we explain some of the exotic enhancements and predict a couple of enhancement structures., Comment: 4 pages, 1 table, conference paper of XIth Quark Connfinement and the Hadron Spectrum held at St. Petersburg, Russia on Sept. 8-12

Inspired by the abundant experimental observation of axial-vector states, we study whether the observed axial-vector states can be categorized into the conventional axial-vector meson family. In this paper we carry out an analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial-vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial-vector mesons, which are valuable for further experimental exploration of the observed and predicted axial-vector mesons., Comment: 18 pages, 11 tables and 25 figures. More discussion added and typos corrected. Accepted by Phys. Rev. D

Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family, in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial and orbital excitations in the charmed-strange meson family, which will be valuable task in LHCb, forthcoming BelleII and PANDA., Comment: 16 pages, 7 tables and 7 figures. Accepted by PRD

Stimulated by the recent BESIII observation of a new resonance in $e^+ e^- \to \omega \chi_{c0}$ and by the fact that this state is consistent with our predicted $\psi(4S)$, in this work we estimate the meson loop contribution to $\psi(4S) \to \omega \chi_{c0}$. The evaluation indicates that our theoretical estimate can overlap with the experimental data in a reasonable parameter range. This fact shows that introduction of the missing higher charmonium $\psi(4S)$ provides a possible explanation to the recent BESIII observation. The upper limit of a branching ratio of $\psi(4S) \to \eta J/\psi$ is also predicted as $1.9 \times 10^{-3}$, which can be further tested by BESIII, Belle and forthcoming BelleII., Comment: 8 pages, 6 figures and 2 tables. More discussions added. Accepted by PRD

The pseudoscalar tensor states, $\pi_2$, $\eta_2$, and $K_2$, are systematically studied through the Okubo-Zweig-Iizuka- allowed two-body strong decays, including both the observed states reported by the Particle Data Group and the predicted states. Phenomenological analysis combined with the experimental data not only can test the assignments to these discussed states, but it can also predict more abundant information {on} their partial decay widths, which is helpful in the experimental study of these observed and predicted pseudotensor states., Comment: 15 pages, 15 figures, and 7 tables. Accepted by PRD

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., Comment: 8 pages, 3 figures and 4 tables. More discussions added and typos corrected. Accepted by Eur. Phys. J. C

In this work, we carry out the study on $\Upsilon(5S)\to \chi_{bJ}\omega$ ($J=0,1,2$) by considering the hadronic loop mechanism. Our results show that the Belle's preliminary data of the branching ratios for $\Upsilon(5S)\to \chi_{bJ}\omega$ can be well reproduced in our calculation with a common parameter range, which reflects the similarity among these $\Upsilon(5S)\to \chi_{bJ}\omega$ decays of concern., Comment: 6 pages, 3 figures, 1 table. More discussions and explanations added. Accepted by Phys. Rev. D

Inspired by the similarity of mass gaps of $J/\psi$ and $\Upsilon$ families, the prediction of missing higher charmonium with mass $4263$ MeV and very narrow width is made. In addition, the properties of two charmonium-like states, $X(3940)$ and $X(4160)$, and charmonium $\psi(4415)$ are discussed. Here, $X(3940)$ as $\eta_c(3S)$ is established while the explanation of $X(4160)$ to be $\eta_c(4S)$ is fully excluded and $\eta_c(4S)$ is typically a very narrow state. These predictions can be accessible at BESIII, Belle and BelleII in near future., Comment: 5 pages, 5 figures and 1 table. More discussions added. Accepted by Eur. Phys. J. C