Hadron Cascade Model PACIAE Research Articles

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

Inspired by the BESIII newest observation of X(2370) glueball-like particle, we search its productions in both e+e− collisions at s=4.95 GeV and proton-proton (pp) collisions at 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 sss¯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−Λ¯ or Σ−Σ¯, or by three mesons of π+π−η′, K+K−η′, or KS0KS0η′ 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 X(2370) production in e+e− collisions, but also serve as a prediction for the 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. Published by the American Physical Society 2024

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

The production of exotic hadron X(3872) in pp collisions at s=2.76TeV 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 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 X(3872) compact tetraquark state or molecular state. Published by the American Physical Society 2024

Linear scaling of lepton charge asymmetry in W± production in ultra-relativistic nuclear collisions from PACIAE model

The lepton charge asymmetry in [Formula: see text] production in the nuclear collisions at [Formula: see text][Formula: see text]TeV is investigated with a parton and hadron cascade model PACIAE. Recently published ALICE and the ATLAS data of lepton charge asymmetry are well reproduced. An interesting linear scaling behavior is observed in the lepton charge asymmetry as a function of the collision system valence quark number asymmetry among different sizes of nuclear collision systems at [Formula: see text][Formula: see text]TeV. This linear scaling behavior may serve as an additional constraint on the PDF (nPDF) extractions.

The production of charged particles and the kaonic nuclei K−pp and K+p̄p̄ in Au + Au collisions at s = 130 GeV

This study investigates the production of charged particles and the kaonic nuclei [Formula: see text] and [Formula: see text] in [Formula: see text] collisions at [Formula: see text] GeV. The parton and hadron cascade model PACIAE 2.1 is used to calculate the yield of charged particles, and the Dynamically Constrained Phase–space Coalescence (DCPC) model is used to calculate the yield of kaonic nuclei. Results showed that the yield of charged particles was consistent with experimental data from the STAR detector at Brookhaven National Laboratory (United States). The data also revealed that the simulated yield of [Formula: see text] was greater than the yield of [Formula: see text]. The kaonic nuclei [Formula: see text] and [Formula: see text] are probably formed by [Formula: see text](or [Formula: see text]) directly trapping two protons (or antiprotons).

PACIAE 2.2.1: An updated issue of the parton and hadron cascade model PACIAE 2.2

The parton and hadron cascade model PACIAE 2.2 (cf. Yan et al. (2018) [11]) has been upgraded to the new issue of PACIAE 2.2.1 with the chiral magnetic effect (CME). The charge correlation parameter, γss and γos, which is typically used to “detect” the CME, is calculated by PACIAE 2.2.1 in Au+Au and Pb+Pb collisions, and the result is consistent with the STAR and ALICE data. As an example, PACIAE 2.2.1 model is employed to mimic the pseudorapidity distribution (dNch/dη) and transverse momentum spectra (pT) of charged particles in non-central Au+Au collisions at RHIC energy and Pb+Pb collisions at LHC energy. The chiral magnetic effect is found to partly affect the final-state basic observables in relativistic nuclear collisions. By this new issue a more realistic dynamical evolution of relativistic nuclear collisions can be depicted. Program summaryProgram Title: PACIAE version 2.2.1CPC Library link to program files:https://doi.org/10.17632/w3g68dj4d9.3Code Ocean capsule:https://codeocean.com/capsule/3695338Licensing provisions: CC By 4.0Programming language: FORTRAN 77 or GFORTRANJournal reference of previous version: Comput. Phys. Comm. 224 (2018) 417Does the new version supersede the previous version?: No.Reasons for the new version: In order that PACIAE 2.2.1 model is now able to simulate the CME-related physics and a more realistic dynamical evolution scenario in the relativistic nucleus-nucleus collisions.Summary of revisions: In PACIAE 2.2.1 model the chiral magnetic effect is introduced. The CME-induced charge separation mechanism [7] into the initial partonic states is artificially added by switching py values for a fraction f of the downward moving partons with those of the corresponding upward moving antipartons.Nature of problem: PACIAE is based on PYTHIA, where it has no any mechanisms to generate the chiral magnetic effect (CME). The CME is a novel transport phenomenon arising from the interaction between quantum anomalies and strong magnetic fields in the ultra-relativistic nuclear collisions. Charge separation is an important consequence of the CME. In order to depict the CME, the corresponding upgrade about introducing a global charge separation scheme into the initial partonic states is highly required.Solution method: The global CME-induced charge separation mechanism [7] into the initial partonic states is introduced by switching py values for a fraction f of the downward moving partons with those of the corresponding upward moving antipartons.Additional comments including restrictions and unusual features: PACIAE 2.2.1 has three versions of PACIAE 2.2.1a, 2.2.1b, and 2.2.1c. PACIAE 2.2.1a is for the elementary collision (here no upgraded from PACIAE 2.2a). PACIAE 2.2.1b and PACIAE 2.2.1c are for the nucleus-nucleus collision of A + A with input file of usu.dat. PACIAE 2.2.1b and PACIAE 2.2.1c are similar in the physical contents but are different in the topological structure [8].•Using the attached input file of usux.dat to run 1000 events for the s = 200 GeV Non Single Diffractive pp collision by PACIAE 2.2.1a takes ≈0.5 min.•Using the attached input file of usu.dat to run 10 events for the 35%-45% non-central Au+Au collisions at sNN = 200 GeV by PACIAE 2.2.1b takes ≈6 min.•Using the attached input file of usu.dat to run 10 events for the 35%-45% non-central Au+Au collisions at sNN = 200 GeV by PACIAE 2.2.1c takes ≈8 min.

Strange particle production in relativistic nucleus-nucleus collisions in the RHIC BES energy region**Supported by National Natural Science Foundation of China (11475068, 11247021), Excellent Youth Foundation of Hubei Scientific Committee (2006ABB036) and Key Laboratory foundation of Quark and Lepton Physics (Hua-Zhong Normal University)(QLPL2014P01)

The parton and hadron cascade model PACIAE is used to investigate strange particle production in Au + Au collisions at in different centralities and at , 11.5 and 7.7 GeV in the most central collision, respectively. It is shown that the transverse momentum distributions of strange particles by the PACIAE model fit the RHIC Beam Energy Scan experimental results well.

An upgraded issue of the parton and hadron cascade model, PACIAE 2.2

The parton and hadron cascade model PACIAE 2.1 (cf. Comput. Phys. Commun. 184 (2013) 1476) has been upgraded to the new issue of PACIAE 2.2. By this new issue the lepton–nucleon and lepton–nucleus (inclusive) deep inelastic scatterings can also be investigated. As an example, the PACIAE 2.2 model is enabled to calculate the specific charged hadron multiplicity in the e−+p and e−+D semi-inclusive deep-inelastic scattering at 27.6 GeV electron beam energy. The calculated results are well comparing with the corresponding HERMES data. Additionally, the effect of model parameters α and β in the Lund string fragmentation function on the multiplicity is studied. Program summaryProgram title: PACIAE version 2.2Catalogue identifier: AEKI_v2_2Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKI_v2_2.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 297,665No. of bytes in distributed program, including test data, etc.: 2,063,650Distribution format: tar.gzProgramming language: FORTRAN 77.Computer: DELL Studio XPS and/or others with a FORTRAN 77 compiler.Operating system: Linux with FORTRAN 77 compiler.RAM: ≈ 1 GBClassification: 11.1, 17.8.Does the new version supersede the previous version?: YesCatalogue identifier of previous version: AEKI_v2_0Journal reference of previous version: Comput. Phys. Comm. 184 (2013) 1476Nature of problem: The lepton inclusive and semi-inclusive deep inelastic scattering (DIS and SIDIS) off nuclear target have greatly contributed to the parton structure of hadron, the parametrization of parton distribution function (PDF), and the extraction of fragmentation function (FF). Unfortunately, the PACIAE 2.1 model is unable to describe the lepton–nucleon and lepton–nucleus DIS (SIDIS), the corresponding upgrade is highly required.Solution method: The parton and hadron cascade model of PACIAE 2.1 is upgraded to PACIAE 2.2 with the possibility of investigating the lepton–nucleon and lepton–nucleus DIS (SIDIS). In the PACIAE 2.2 model the lepton–nucleon and lepton–nucleus DIS are treated the same as proton–nucleon and proton–nucleus collisions in PACIAE 2.1, respectively. However, the lepton–nucleon DIS cross section is used instead of the nucleon–nucleon cross section in the initiation stage of the PACIAE model.Reasons for new version: In order that the PACIAE 2.2 model is now also able to simulate the lepton–nucleon and lepton–nucleus DIS.Summary of revisions: In the PACIAE 2.2 model the lepton–nucleon and lepton–nucleus DIS are dealt in the same way as the proton–nucleon and proton–nucleus collisions in PACIAE 2.1, respectively. However, the lepton–nucleon DIS cross section is employed instead of nucleon–nucleon cross section.Restrictions: Depend on the problem studied.Running time: PACIAE 2.2 has three versions of PACIAE 2.2a, 2.2b, and 2.2c. PACIAE 2.2a is for the elementary collision, such as pp, pp, and e+e− collisions, as well as the lepton–nucleon DIS, with input file of usux.dat. PACIAE 2.2b and PACIAE 2.2c are for the nuclear-nucleus collision of p+A and A+B as well as the lepton–nucleus DIS with input file of usu.dat. PACIAE 2.2b and 2.2c are similar in the physical contents but are different in the topological structure (see text for the details). •Using the attached input file of usux.dat to run 1000 events for the s=200GeV Non Single Diffractive pp collision by PACIAE 2.2a takes 0.5 min.•Using the attached input file of usu.dat to run 10 events for the 10%–40% most central Au + Au collisions at sNN=200GeV by PACIAE 2.2b takes 4 min.•Using the attached input file of usu.dat to run 10 events for the 10%–40% most central Au + Au collisions at sNN=200GeV by PACIAE 2.2c takes 8 min.

Comparative study for non-statistical fluctuation of net- proton, baryon, and charge multiplicities

We investigate the higher moments of net-proton, net-baryon, and net-charge event distributions in Au+Au collisions at from 11.5 to 200 GeV. The non-statistical moments are defined as the differences between the real event moments and mixed event moments. The real events are generated with the parton and hadron cascade model PACIAE, while the mixed events are constructed by combining particles randomly selected from different real events. It is found that the theoretical results of net-proton and net-charge real higher moment excitation functions of Sσ and κσ2 are consistent with the STAR data, and that the properties of higher moment excitation functions are significantly dependent on the window sizes. In addition, the centrality dependence of the net-proton, net-baryon, and net-charge non-statistical higher moments are also studied.

Systematic study of elliptic flow parameter in the relativistic nuclear collisions at RHIC and LHC energies

We employed the new issue of a parton and hadron cascade model PACIAE 2.1 to systematically investigate the charged particle elliptic flow parameter v2 in the relativistic nuclear collisions at RHIC and LHC energies. With randomly sampling the transverse momentum x and y components of the particles generated in string fragmentation on the circumference of an ellipse instead of circle as originally, the calculated charged particles v2(η) and v2(pT) fairly reproduce the corresponding experimental data in the Au+Au/Pb+Pb collisions at sNN=0.2/2.76 TeV. In addition, the charged particles v2(η) and v2(pT) in the p+p collisions at s=7 TeV as well as in the p+Au/p+Pb collisions at sNN=0.2/5.02 TeV are predicted.

Elliptic flow parameter in Au+Au and p+Au collisions at top RHIC energy

The new issue of parton and hadron cascade model PACIAE 2.1 is utilized investigating the charged particle elliptic flow parameter v2 in Au + Au and p+ Au collisions at top RHIC energy. If the transverse momenta px and py of particles from string fragmentation are randomly sampled on the circumference of an ellipse instead of circle originally the PHENIX charged particle v2(η) and v2(pT) data in the 20-40% and 40-50% central Au + Au collisions at [Formula: see text] are fairly reproduced by the PACIAE 2.1 calculations, respectively. In addition, the charged particle v2(η) and v2(pT) in the p+ Au collisions at [Formula: see text] are predicted. It turned out that the charged particle elliptic flow parameter v2 may reach a measurable value of ~0.04 in the above p+ Au collisions.

PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0

We have updated the parton and hadron cascade model PACIAE 2.0 for relativistic nuclear collisions (cf. Comput. Phys. Comm. 183(2012)333) to the new issue of PACIAE 2.1. The PACIAE model is based on PYTHIA. In the PYTHIA model, once the generated particle/parton transverse momentum $p_T$ is randomly selected, its component of $[p_x,p_y]$ was originally put on the circle with radius $p_T$ randomly. It is now replaced by put on the circumference of ellipse with half major and minor axes of $p_T(1+\delta_p)$ and $p_T(1-\delta_p)$, respectively, in order to investigate better the transverse momentum anisotropy in final hadronic state.

Higher-moment singularities explored by net-proton nonstatistical fluctuations

We use the non-statistical fluctuation instead of the full one to explore the higher moment singularities of net proton event distributions in the relativistic Au+Au collisions at $\sqrt{s_{NN}}$ from 11.5 to 200 GeV calculated by the parton and hadron cascade model PACIAE. The PACIAE results of mean ($M$), variance ($\sigma^2$), skewness ($S$), and kurtosis ($\kappa$) are consistent with the corresponding STAR data. Non-statistical moments are calculated as the difference between the moments derived from real events and the ones from mixed events, which are constructed by combining particles randomly selected from different real events. An evidence of singularity at $\sqrt{s_{NN}}\sim$ 60 GeV is first seen in the energy dependent non-statistical $S$ and $S\sigma$.

Impact of parton rescattering on analysis of [formula omitted] collision data at LHC energies

ALICE, CMS, and ATLAS measurements for p+p collisions at LHC energies (s=0.9, 2.36, and 7 TeV) are analyzed systematically using the parton and hadron cascade model PACIAE which is based on the PYTHIA model. We emphasize the impact of parton rescattering on the analysis of experimental data by comparing the PACIAE results (with parton rescattering) to the PYTHIA ones (without parton rescattering). It turned out that the parton rescattering in the initial fireball plays an role in understanding the experimental data and the parton rescattering effect increases with the reaction energy increasing.