arXiv subjects

Zhi-Lei She

Publications and source records attributed to Zhi-Lei She.

At least 19 recordsLinked to original sources

arXiv2026

Shedding light on the nature of $ϕ(2170)$ with the parton and hadron cascade model PACIAE

The nature of $ϕ(2170)$ remains open. We simulate its production in $e^+e^-$ collisions at $\sqrt{s}=4.95$ GeV using PACIAE 4.0, which sequentially generates the final partonic state (FPS) and the final hadronic state (FHS). While previous studies have interpreted $ϕ(2170)$ as an $ss\bar{s}\bar{s}$ or a $u\bar{u}s\bar{s}$ state, the $U(1)$ anomaly coupling allows non-strange quarks to couple to a vector $s\bar{s}$ component via soft-gluon interactions. This motivates us to also explore the $d\bar{d}s\bar{s}$ tetraquark configuration. In addition, we consider $ϕ(2170)$ as an excited strangeonium state, an $s\bar{s}g$ hybrid state, a $\barΛΛ$ bound state, and a $ϕK^+K^-$ resonance state. The strangeonium, hybrid, and tetraquark candidates are formed by coalescing their constituent partons in the FPS using the dynamically constrained phase-space coalescence model. The $\barΛΛ$ and $ϕK^+K^-$ states are produced via recombination of their constituent hadrons in the FHS. We calculate the orbital angular momentum quantum number of each candidate in its rest frame and perform spectral classification. Given $J^{PC}=1^{--}$, $ϕ(2170)$ can be interpreted as a $D$-wave $s\bar{s}$, a $P$-wave $s\bar{s}g$, a $P$-wave $u\bar{u}s\bar{s}/d\bar{d}s\bar{s}/ss\bar{s}\bar{s}$, an $S$-wave $\barΛΛ$, or an $S$-wave $ϕK^+K^-$ state. The yields of the $D$-wave $s\bar{s}$, $P$-wave $s\bar{s}g$, $u\bar{u}s\bar{s}$ and $d\bar{d}s\bar{s}$ states are of order $10^{-4}$; those for the $S$-wave $\barΛΛ$ and $ϕK^+K^-$ states are of order $10^{-5}$; while the $P$-wave $ss\bar{s}\bar{s}$ yield is of order $10^{-6}$. Moreover, significant discrepancies are observed in the rapidity distributions and the $p_T$ spectra among the various candidates. These discrepancies could serve as valuable criteria for unraveling the nature of $ϕ(2170)$.

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arXiv2026

A novel approach for studying two-particle momentum correlation function in relativistic nuclear collisions

Two particle momentum correlation functions provide a nontrivial tool for probing the strong interaction and/or extracting particle emission source information in relativistic nuclear collisions. Although transport models can describe the microscopic phase-space evolution of the collision system, calculating correlation functions within the framework of transport models remains challenging. In this paper, we employ the mixed-event technique to calculate two particle momentum correlation function as $C(k^*)= \mathcal{N} ξ(k^*)\frac{N_{\mathrm{same}}(k^*)}{N_{\mathrm{mixed}}(k^*)}$ based on the parton and hadron cascade model PACIAE simulated final hadronic state (FHS) with introducing a modification factor $ξ(k^*)$ to improve the treatment of final-state interactions and quantum statistics effects in the PACIAE model. The simulated results show good agreement with the ALICE data for $Kp$, $pp$, $pΛ$, and $ΛΛ$ momentum correlation functions in $pp$ collisions at $\sqrt{s}=7$ TeV. On the other hand, the particle emission source radius of the correlated pairs are also evaluated based on the simulated FHS self-consistently. Since the PACIAE model employs hadron-hadron cross sections derived from the additive quark model, the calculation of two-particle momentum correlation functions does not require prior assumptions about the interaction between the two correlated particles. This successful ``PACIAE + modification factor" approach may shed light on the future study of momentum correlation functions for dimesons, dibaryons, and even diexotic hadrons.

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arXiv2026

A comparative study of $T_{cc}$ versus $X(3872)$ production in $pp$ collisions at $\sqrt{s}=$ 7 TeV

The production of exotic hadrons $T_{cc}$ and $X(3872)$ in $pp$ collisions at $\sqrt{s}=7$ TeV is compared using the parton and hadron cascade model PACIAE together with the dynamically constrained phase-space coalescence model DCPC. In the simulation, the compact tetraquark state and the loose molecular state are formed in the partonic and hadronic levels, respectively. Our analysis of the transverse momentum spectra reveals a significant discrepancy between the compact state and the molecular states. Furthermore, the production asymmetry between $T_{cc}^+$ and $T_{cc}^-$ is investigated. Finally, the coalescence parameters are extracted from the calculated spectra to further characterize the emission source properties. These distributions are proposed as valuable criteria for distinguishing between these states and investigating their internal structures in experimental measurements.

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arXiv2026

Deciphering the nature of $X(2300)$ with the PACIAE model

Inspired by the BESIII newest observation of an axial-vector particle $X(2300)$ in the $ψ(3686)\rightarrow ϕηη'$ process, we simulate its production in $e^+e^-$ collisions at $\sqrt{s}=4.95$ GeV using the parton and hadron cascade model PACIAE 4.0. In this model, the final partonic state (FPS) and hadronic state (FHS) are simulated and recorded sequentially. We propose, for the first time, that $X(2300)$ could be a $q\bar{q}s\bar{s}$ ($q=u/d$) state or a hadro-strangeonium state, i.e., a bound system of a strangeonium and a light hadron. The excited strangeonium candidate is formed by coalescing an $s\bar{s}$ quark pair in the FPS with the quantum statistical mechanics inspired dynamically constrained phase-space coalescence model. The tetraquark candidates of $q\bar{q}s\bar{s}$ and $ss\bar{s}\bar{s}$ are similarly produced by coalescing four constituent quarks in the FPS. In contrast, a hadro-strangeonium candidate emerges from the recombination of the constituent $ϕ$ and $η/η$ in the FHS. We then calculate the $X(2300)$'s orbital angular momentum quantum number in its rest frame and perform the spectral classification for each of the above candidates. Given its quantum numbers $J^{PC}=1^{+-}$, $X(2300)$ is identified as a $P$-wave $s\bar{s}$, an $S$-wave $q\bar{q}s\bar{s}/ss\bar{s}\bar{s}$ or $S$-wave $ϕη'/ϕη$ candidate. For the first time, we estimate the production rates for these configurations. The $P$-wave $s\bar{s}$ and $S$-wave $q\bar{q}s\bar{s}$ states are produced at rates on the order of $10^{-5}$, whereas the $S$-wave $ss\bar{s}\bar{s}$ and $ϕη'/ϕη$ states appear at rates on the order of $10^{-6}$. Moreover, significant discrepancies are observed in the rapidity and transverse momentum distributions among different candidates. These discrepancies could be served as valuable criteria for deciphering the nature of $X(2300)$.

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arXiv2025

Inclusive $J/ψ$ productions in pp collisions at $\sqrt{s}=$ 5.02, 7, and 13 TeV with the PACIAE model

We investigate the inclusive $J/ψ$ production in proton-proton (pp) collisions at center-of-mass energies $\sqrt{s} = 5.02$, 7, and 13 TeV using the PACIAE 4.0 model. This model extends PYTHIA 8.3 by incorporating partonic and hadronic rescatterings before and after hadronization, respectively. Compared to our earlier study [K.-F. Ye et al., Phys. Rev. C 109, 035201 (2024)], which considered only the color-singlet processes, the present work includes both the color-singlet and color-octet contributions within the non-relativistic QCD (NRQCD) framework. In addition to NRQCD, we also consider the contributions from the cluster collapse and weak decays of $b$-hadrons. We find that the simulated inclusive $J/ψ$ transverse momentum differential cross sections agree well with the experimental data at both the middle and forward rapidities. We provide a quantitative analysis of the relative contributions for different production mechanisms and their energy and rapidity dependence in the inclusive $J/ψ$ production. Furthermore, we offer a quantification of the relative contributions of the various components and their energy and rapidity dependence in the NRQCD channels, including the direct production via the hard scattering and the feed-down from the decays of heavier charmonium states such as $ψ(2S)$, $χ_{c0}$, $χ_{c1}$, and $χ_{c2}$. Finally, we examine the effects of partonic and hadronic rescatterings and offer the quantitative estimate of their impact on the $J/ψ$ production. These results are entirely new and represent a significant step forward in understanding the mechanisms of the inclusive $J/ψ$ production in high-energy pp collisions.

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arXiv2025

Investigation of $T_{cs0}^{*}(2870)^{0}$ in $pp$ collisions at $\sqrt{s}$ = 7 TeV with the PACIAE model

We have used the parton and hadron cascade model PACIAE together with the Dynamically Constrained Phase-space Coalescence model (DCPC) to study the $T_{cs0}^{*}(2870)^{0}$ production in $pp$ collision at $\sqrt{s}$ = 7 TeV, following the LHCb observation of $T_{cs0}^{*}(2870)^{0}$ in the $B^{-}\to D^{-}D^{0}K^{0}_{S}$ decays in $pp$ collisions at $\sqrt{s}$ = 7, 8, and 13 TeV [PRL 134(2025)101901]. The final hadronic states of the $pp$ collisions at $\sqrt{s}$ = 7 TeV are first simulated by the PACIAE model. Four sets of $T_{cs0}^{*}(2870)^{0}$ candidates are then recombined by the DCPC model using the constituent meson pair of $D^{0}K^{0}_{S}$, $D^{+}K^{-}$, $D^{*+}K^{*-}$, and $D^{*0} \bar{K}^{*0}$ based on the above simulated final hadronic states, respectively. We calculate their rapidity distributions, transverse momentum spectra, and angular distribution between the two component mesons, as well as angular distribution between $D$ component meson and $T_{cs0}^{*}(2870)^{0}$. Our results show that the yields of four $T_{cs0}^{*}(2870)^{0}$ candidates follow the magnitude order of $D^{0}K^{0}_{S}$ $>$ $D^{+}K^{-}$ $>$ $D^{*+}K^{*-}$ $\sim$ $D^{*0} \bar{K}^{*0}$. Similar ordering behavior is also observed in the aforementioned distributions.

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arXiv2025

Strangeness production in $p$Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV in the PACIAE model

We present a study of the single- and multi-strange particle productions in $p$Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV using the PACIAE 4.0 model. The effects of the color reconnection (CR), rope hadronization (RH) as well as the partonic and hadronic rescatterings (PRS and HRS) on their productions are investigated, respectively. There are two kinds of CR considered: the multiparton interactions-based CR (MPI-CR) and the quantum chromodynamics-based CR (QCD-CR). The four mechanisms studied have little effect on kaon production. However, the QCD-CR scheme incorporating the junction topology gives an enhanced baryon production, but it is still not enough to describe the integrated yields of strange baryons. The combination of QCD-CR and RH scheme together with the flavor ropes (FR) and the string shoving (SS), i.e., QCD-CR+FR+SS, provides a good description of the production of strange baryons. PRS has a weak effect but HRS exerts a promoting effect on the production of multi-strange baryons ($Ξ$ and $Ω$).

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arXiv2025

The charmonium-like exotic hadron productions in $e^+e^-$ collisions at the BESIII energy with the PACIAE model

Inspired by the BESIII observation of exotic hadron $G$(3900) in $e^+e^-\rightarrow D\bar D$ process [PRL 133(2024)081901], we use the parton and hadron cascade model PACIAE to simulate the productions of charmonium-like exotic hadrons including $X(3872)$, $Z_{c}(3900)^0$ and $G(3900)$ in the $e^+e^-$ annihilations at $\sqrt s$=4.95 GeV. The charmonium-like candidates are recombined by Dynamically Constrained Phase-space Coalescence model using component mesons $D\bar D$ (for $G(3900)$) or $D\bar D^*/\bar DD^*$ (for $X(3872)$, $Z_{c}(3900)^0$ and $G(3900)$) in the PACIAE simulated final hadronic state. We then calculate, for the first time, the charmonium-like candidate's orbital angular momentum quantum number in its rest frame and perform the spectral classification for each of the above candidates. For $G(3900)$, as its $J^{PC}$ is $1^{--}$, it is identified as the $P$-wave $D\bar D$ or $D\bar D^*/\bar DD^*$ state. Meanwhile, for $X(3872)$ and $Z_{c}(3900)^0$, as their $J^{PC}$s are, respectively, $1^{++}$ and $1^{+-}$, they are identified as the $S$-wave $D\bar D^*/\bar DD^*$ candidates. It is observed that the yield of the $P$-wave $G(3900)$ composed of $D\bar D^*/\bar DD^*$ is significantly larger than that composed of $D\bar D$. Moreover, in the $D\bar D^*/\bar DD^*$ channel, the yield of the $P$-wave $G(3900)$ is around three times as large as the yield of the $S$-wave $Z_{c}(3900)^0$, and it is around two orders of magnitude as large as the yield of the $S$-wave $X(3872)$. Finally, significant discrepancies are observed in the transverse momentum spectra and the rapidity distributions among the $X(3872)$, $Z_{c}(3900)^0$ and $G(3900)$ states. These discrepancies are proposed as valuable criteria for identifying the different charmonium-like exotic hadrons from each other.

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arXiv2025

Coalescence production of sexaquark with three diquarks in high-energy nuclear collisions

The coalescence production of sexaquark, a hypothetical stable state with quark content $(uuddss)$, is investigated by the parton and hadron cascade model PACIAE in $pp$ collisions at $\sqrt s = 7$ TeV. In this work, the compact sexaquark bound state of three diquarks is formed in the final partonic state by a two-step approach, which involves ``diquark" formation via partonic coalescence and sexaquark construction with dynamically constrained phase-space coalescence model successively. The yields, yield ratios, and dependences of spatial parameters (the size of diquark $D_{0}$ and the radius of sexaquark $R_{0}$) of (anti-)sexaquark are predicted. The yields of a hadronic molecule H-dibaryon $\mathrm{H}(ΛΛ)$ generated in the final hadronic state are also compared. These estimates provide references for future sexaquark searches and other exotic state studies, such as dibaryons.

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arXiv2024

A Brief Introduction to PACIAE 4.0

Parton And-hadron China Institute of Atomic Energy (PACIAE) is a multipurpose Monte Carlo event generator developed to describe a wide range of high-energy collisions, including lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. It is built based on the PYTHIA program, and incorporates parton and hadron cascades to address the nuclear medium effects. PACIAE 4.0 is the new generation of PACIAE model surpassing the version 3.0. In PACIAE 4.0, the old fixed-format FORTRAN 77 code has been refactored and rewritten by the free-format modern Fortran and C++ languages. The C++-based PYTHIA 8.3 is interfaced in, while previous versions connected to the Fortran-based PYTHIA 6.4 only. Several improvements are also introduced, which enable PACIAE 4.0 to contain more physics and features to model the high-energy collisions. This is the first attempt to transition PACIAE from Fortran to C++.

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arXiv2024

X(2370) glueball-like particle productions in $e^+e^-$ collisions at the BESIII energy and in pp collisions at the LHC energy with PACIAE model

Inspired by the BESIII newest observation of X(2370) glueball-like particle, we search its productions in both $e^+e^-$ collisions at $\sqrt{s}=$ 4.95 GeV and proton-proton (pp) collisions at $\sqrt{s}=$ 13 TeV with a parton and hadron cascade model PACIAE. In this model, the final partonic state (FPS) and the final hadronic state (FHS) are consecutively simulated and recorded. The X(2370) glueball- or tetraquark-state is then, respectively, recombined by two gluons or four quarks $ss\bar{s}\bar{s}$ in the FPS using the quantum statistical mechanics inspired dynamically constrained phase-space coalescence (DCPC) model. The X(2370) molecular-state is recombined by the baryon-antibaryon of $Λ$-$\barΛ$ or $Σ$-$\barΣ$, or by three mesons of $π^+π^{-}η'$, $K^+K^-η'$, or $K_S^0K_S^0η'$ in the FHS using DCPC model. In both $e^+e^-$ and pp collisions, significant discrepancies in the yields, the transverse momentum spectra and the rapidity distributions among the X(2370) glueball-, tetraquark-, and molecular-state are observed. These discrepancies are proposed as valuable criteria identifying the X(2370) different states from each other. Our results not only support the BESIII observation of glueball-like particle $\rm X(2370)$ production in $e^+e^-$ collisions, but also serve as a prediction for the $\rm X(2370)$ production in pp collisions. We strongly suggest the experimental measurement of the X(2370) glueball-like particle production in pp collisions at the LHC energies.

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arXiv2024

Identifying an $\rm X(3872)$ tetraquark state versus a molecular state by formation time, velocity and temperature in relativistic nuclear collisions

The production of exotic hadron $\rm X(3872)$ in $pp$ collisions at $\sqrt{s}=2.76\,\mathrm{TeV}$ is investigated by the parton and hadron cascade model PACIAE in this work. In the simulation the final partonic state (quark matter, QM) and the final hadronic state (hadron matter, HM) are continuously processed and recorded. The $\rm X(3872)$ compact tetraquark state and loose molecular state are, respectively, coalesced and recombined in the QM and HM with the quantum statistical mechanics inspired dynamically constrained phase-space coalescence model. The formation time, velocity and temperature of QM (tetraquark state) and HM (molecular state) are proposed as identifying criteria between the two states. Our results in transverse momentum spectrum and rapidity distribution, etc. show a significant discrepancy between the two states and confirm that they are also valuable criteria identifying the $\rm X(3872)$ compact tetraquark state or molecular state.

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arXiv2024

Confirming the glueball-like particle $X(2370)$ productions in $e^+e^-$ collisions at BESIII energy with PACIAE model

The parton and hadron cascade model {\footnotesize PACIAE} is employed to confirm the BESIII newest observation of glueball-like particle $\rm X(2370)$ production in $e^+e^-$ collisions at $\sqrt{s}=4.95\,\mathrm{GeV}$. We coalesce the $\rm X(2370)$ glueball state with two gluons in the simulated partonic final state by the Dynamically Constrained Phase-space Coalescence ({\footnotesize DCPC}) model. Alternative configuration of $\rm X(2370)$ molecular state is recombined in the simulated hadronic final state with $π^{+},π^{-},K^{+}, K^{-},K_{S}^{0},K_{S}^{0}$ and $η'$ by {\footnotesize DCPC} model. The resulted particle transverse momentum spectrum and rapidity distribution, etc. show a significant discrepancy between the two states. They are not only serving as criteria to distinguish the $\rm X(2370)$ glueball state or molecular state, but also confirming the BESIII observation of glueball-like particle $\rm X(2370)$ productions in $e^+e^-$ collisions.

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arXiv2024

Energy dependence of $J/ψ$ production in pp collisions with the PACIAE model

In this work we investigate the $J/ψ$ production in proton-proton collisions at the center-of-mass energy ($\sqrt{s}$) equal to 2.76, 5.02, 7, 8 and 13 TeV with a parton and hadron cascade model PACIAE 2.2a. It is based on PYTHIA but extended considering the partonic and hadronic rescatterings before and after hadronization, respectively. In the PYTHIA sector the $J/ψ$ production quantum chromodynamics processes are selected specially and a bias factor is proposed correspondingly. The calculated total cross sections, the differential cross sections as a function of the transverse momentum and the rapidity of $J/ψ$ in the forward rapidity region reproduce the corresponding experimental measurements reasonably well. In the mid-rapidity region, the double differential cross sections at $\sqrt{s}=$ 5.02, 7 and 13 TeV are also in a good agreement with the experimental data. Moreover, we interpolate the double differential cross section as well as the total cross section of $J/ψ$ in the mid-rapidity region at $\sqrt{s}=$ 8 TeV, which could be validated if the experimental data is available.

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arXiv2023

An introduction to the parton and hadron cascade model PACIAE 3.0

We introduce a parton and hadron cascade model PACIAE 3.0 based on PYTHIA 6.428 and the PACIAE 2.2 program series. The simulation framework of C-, B-, and A-loops are designed for the high energy ($\sqrt{s_{NN}}\geq 3$ GeV) and low energy ($\sqrt{s_{NN}}<3$ GeV) nuclear collisions, respectively, in PACIAE 3.0. In the C-loop simulation, the parton-parton inelastic scattering processes are added in the partonic rescattering process. The single string structure and multiple string interaction mechanism have been introduced investigating the strangeness enhancement in C- and B-loop. An improved mapping relation between the centrality percentage definition and the impact parameter definition is proposed responding the observation of $b_{max}\approx 20$ fm from ALICE, ATLAS, and CMS collaborations. We have extensively modified the phenomenological coalescence hadronization model. The PACIAE 3.0 model simulated results of particle yield, transverse momentum distribution, and rapidity distribution well reproduce, respectively, the experimental data measured at FOPI, E895, RHIC, and LHC energies.

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arXiv2023

The study on the structure of exotic states $χ_{c 1}(3872)$ via beauty-hadron decays in $pp$ collisions at $\sqrt{s}=8\,\mathrm{TeV}$

A dynamically constrained phase-space coalescence (DCPC) model was introduced to study the exotic state $χ_{c 1}(3872)$ yield for three possible structures: tetraquark state, nuclear-like state, and molecular state respectively, where the hadronic final states generated by the parton and hadron cascade model (PACIAE). The $χ_{c 1}(3872)$/$ψ(2S)$ cross-section ratio from beauty-hadron decays (non-prompt) based on the $χ_{c 1}(3872)$ or $ψ(2S)\to J/ψ{π^+}{π^-}$ bound state in the decay chains as a function of charged-particle multiplicity and transverse momentum in $pp$ collisions at $\sqrt{s}=8\,\mathrm{TeV}$ are calculated. A tetraquark state scenario from PACIAE+DCPC model shows better agreement with the LHCb and ATLAS measurements for the non-prompt $χ_{c 1}(3872)$/$ψ(2S)$ cross-section ratio distributions, indicating that the $χ_{c 1}(3872)$ is more likely to be a compact tetraquark state.

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arXiv2021

A study on the exotic state ${P_{c}(4312),P_{c}(4440),P_{c}(4457)}$ in $pp$ collisions at $\sqrt{s}=7$, 13 TeV

The exotic resonant state $P_{c}^{\pm}(4312)$, $P_{c}^{\pm}(4440)$, and $P_{c}^{\pm}(4457)$ are studied by using the dynamically constrained phase space coalescence DCPC model and PACIAE model in $pp$ collisions at $\sqrt{s}=7$, 13TeV, respectively. We consider exotic state $P_{c}^{\pm}(4312)$, $P_{c}^{\pm}(4440)$ and $P_{c}^{\pm}(4457)$ to be three kinds of possible structures, i.e. pentaquark state, the nucleus-like state, and the molecular state based on $P_c^\pm \to J/ψ{p}{(\bar p)}$ bound state. The yield, the transverse momentum distribution and the rapidity distribution of $P_{c}$ with three different structures are all predicted. The results indicated that the yield is on the order of $10^{-6}$, which might provide reference for experimental research.

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arXiv2021

Investigation of exotic state X(3872) in $pp$ collisions at $\sqrt{s}=$7 and 13 TeV

We have used the dynamically constrained phase space coalescence model to study the production of the exotic state $X(3872)$ based on the hadronic final states generated by the parton and hadron cascade model (PACIAE) with $|y|<1$ and $p_T < 15.5$ GeV/c in $pp$ collisions at $\sqrt{s}=7$ and 13 TeV, respectively. Here the $X(3872)$ is assumed to consist of bound state $D\bar {D^*}$, which can form three possible structures for the tetraquark state, the nucleus-like state, and the molecular state. The yields of three different structures $X(3872)$ were predicted. The transverse momentum distribution and the rapidity distribution of three different structures $X(3872)$ are also presented. Sizable difference can be found in the transverse momentum and rapidity distributions for the three different $X(3872)$ structures.

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