scholarly journals Nuclear Stopping in Central Au+Au Collisions at RHIC Energies

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Ying Yuan ◽  
Nana Guan
Keyword(s):  
Transport Model ◽  
Mean Field ◽  
Heavy Ion ◽  
Quantum Molecular Dynamics ◽  
Field Potentials ◽  
Relativistic Heavy Ion Collider ◽  
Nuclear Stopping ◽  
Phobos Collaboration ◽  
The Mean ◽  
String Fragmentation

Nuclear stopping in central Au+Au collisions at relativistic heavy-ion collider (RHIC) energies is studied in the framework of a cascade mode and the modified ultrarelativistic quantum molecular dynamics (UrQMD) transport model. In the modified mode, the mean field potentials of both formed and “preformed” hadrons (from string fragmentation) are considered. It is found that the nuclear stopping is increasingly influenced by the mean-field potentials in the projectile and target regions with the increase of the reaction energy. In the central region, the calculations of the cascade model considering the modifying factor can describe the experimental data of the PHOBOS collaboration.

scholarly journals PRODUCTION AND RESCATTERING OF STRANGE BARYONS AT ENERGIES AVAILABLE AT THE CERN SUPER PROTON SYNCHROTRON IN A TRANSPORT MODEL WITH HADRON POTENTIALS

2012 ◽  
Vol 27 (03) ◽  
pp. 1250004 ◽  
Author(s):  
QINGFENG LI ◽  
ZHUXIA LI
Keyword(s):  
Transport Model ◽  
Relativistic Quantum ◽  
Mean Field ◽  
Field Potential ◽  
Heavy Ion ◽  
Transverse Mass ◽  
Proton Synchrotron ◽  
Quantum Molecular Dynamics ◽  
Super Proton Synchrotron ◽  
Strange Baryons

A mean-field potential version of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model is used to investigate the production of strange (anti-)baryons, especially the Λs and [Formula: see text]s, from heavy ion collisions at SPS energies. It is found that, with the consideration of both formed and pre-formed hadron potentials in UrQMD, the transverse mass and longitudinal rapidity distributions of experimental data of both Λs and [Formula: see text]s can be quantitatively explained fairly well. Our investigation also shows the equal importance of both the production mechanism and the rescattering process of hadrons for the final yield of strange baryons.

scholarly journals Elliptic flow splitting between protons and antiprotons from hadronic potentials

2020 ◽  
Vol 35 (35) ◽  
pp. 2050289
Author(s):  
Pengcheng Li ◽  
Yongjia Wang ◽  
Jan Steinheimer ◽  
Qingfeng Li ◽  
Hongfei Zhang
Keyword(s):  
Beam Energy ◽  
Relativistic Quantum ◽  
Mean Field ◽  
Elliptic Flow ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collider ◽  
Field Mode ◽  
Flow Splitting ◽  
The Mean ◽  
The Difference

The difference in elliptic flow between protons and antiprotons, produced in [Formula: see text] collisions at center-of-mass energies [Formula: see text], is studied within a modified version of the ultra-relativistic quantum molecular dynamics (UrQMD) model. Two different model scenarios are compared: the cascade mode and the mean field mode which includes potential interactions for both formed and pre-formed hadrons. The model results for the elliptic flow of protons and the relative elliptic flow difference between protons and antiprotons obtained from the mean field mode agree with the available experimental data, while the elliptic flow difference is near zero for the cascade mode. Our results show that the elliptic flow splitting, observed for particles and antiparticles, can be explained by the inclusion of proper hadronic interactions. In addition, the difference in elliptic flow between protons and antiprotons depends on the centrality and the rapidity window. With smaller centrality and/or rapidity acceptance, the observed elliptic flow splitting is more sensitive to the beam energy, indicating a strong net baryon density dependence of the effect. We propose to confirm this splitting at the upcoming experiments from Beam Energy Scan (BES) Phase-II at Relativistic Heavy Ion Collider (RHIC), the Compressed Baryonic Matter (CBM) at Facility for Antiproton and Ion Research (FAIR), High Intensity heavy ion Accelerator Facility (HIAF) and Nuclotron-based Ion Collider fAcility (NICA).

AVERAGE PROPERTY OF FRAGMENTATION REACTION AND MOMENTUM DISSIPATION INDUCED BY HALO-NUCLEI IN HEAVY ION COLLISIONS

2006 ◽  
Vol 15 (05) ◽  
pp. 1069-1086
Author(s):  
JIAN-YE LIU ◽  
WEN-JUN GUO ◽  
ZHONG-ZHOU REN ◽  
WEI ZUO ◽  
XI-GUO LEE ◽  
...  
Keyword(s):  
Density Distribution ◽  
Heavy Ion Collisions ◽  
Halo Nucleus ◽  
Heavy Ion ◽  
Halo Nuclei ◽  
Fragmentation Reaction ◽  
Quantum Molecular Dynamics ◽  
Nuclear Stopping ◽  
Density Distributions ◽  
Ion Collisions

We study systematically the average property of fragmentation reaction and momentum dissipation induced by halo-nuclei in intermediate energy heavy ion collisions for different colliding systems and different beam energies within the isospin dependent quantum molecular dynamics model (IQMD). This study is based on the extended halo-nucleus density distributions, which indicates the average property of loosely inner halo nucleus structure, because the interaction potential and in-medium nucleon-nucleon cross section in IQMD model depend on the density distribution. In order to study the average properties of fragmentation reaction and momentum dissipation induced by halo-nuclei we also compare the results for the halo-nuclear colliding systems with those for corresponding stable colliding systems with same mass under the same incident channel condition. We find that the effect of extended halo density distribution on the fragment multiplicity and nuclear stopping (momentum dissipation) are important for the different beam energies and different colliding systems. For example the extended halo density distributions increase the fragment multiplicity but decrease the nuclear stopping for all of incident channel conditions in this paper.

scholarly journals Comparing Standard Distribution and Its Tsallis Form of Transverse Momenta in High Energy Collisions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Rui-Fang Si ◽  
Hui-Ling Li ◽  
Fu-Hu Liu
Keyword(s):  
Hadron Collider ◽  
Simulated Data ◽  
Heavy Ion ◽  
High Energy ◽  
Central Nucleus ◽  
Quantum Molecular Dynamics ◽  
Relativistic Heavy Ion Collider ◽  
Two Component ◽  
Standard Distribution ◽  
Effective Temperatures

The experimental (simulated) transverse momentum spectra of negatively charged pions produced at midrapidity in central nucleus-nucleus collisions at the Heavy-Ion Synchrotron (SIS), Relativistic Heavy-Ion Collider (RHIC), and Large Hadron Collider (LHC) energies obtained by different collaborations are selected by us to investigate, where a few simulated data are taken from the results of FOPI Collaboration which uses the IQMD transport code based on Quantum Molecular Dynamics. A two-component standard distribution and the Tsallis form of standard distribution are used to fit these data in the framework of a multisource thermal model. The excitation functions of main parameters in the two distributions are analyzed. In particular, the effective temperatures extracted from the two-component standard distribution and the Tsallis form of standard distribution are obtained, and the relation between the two types of effective temperatures is studied.

scholarly journals Strangeness Enhancement at LHC Energies Using the Thermal Model and EPOSLHC Event Generator

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Mahmoud Hanafy ◽  
Omnia S. A. Qandil ◽  
Asmaa G. Shalaby
Keyword(s):  
Cosmic Ray ◽  
Heavy Ion ◽  
Event Generator ◽  
Relativistic Heavy Ion Collider ◽  
Model Calculations ◽  
High Energies ◽  
Particle Ratios ◽  
Strangeness Enhancement ◽  
The Mean ◽  
Good Agreement

The strangeness enhancement signature of QGP formation at LHC energies is carefully tackled in the present study. Based on HRG, the particle ratios of mainly strange and multistrange particles are studied at energies from lower s ~ 0.001 up to 13 TeV. The strangeness enhancement clearly appeared at more high energies, and the ratios are confronted to the available experimental data. The particle ratios are also studied using the Cosmic Ray Monte Carlo (CRMC) interface model with its two different event generators, namely, EPOS 1.99 and EPOSlhc, which show a good agreement with the model calculations at the whole range of the energy. We utilize them to produce some particles ratios. EPOS 1.99 is used to estimate particle ratios at lower energies from AGS up to the Relativistic Heavy Ion Collider (RHIC) while EPOSlhc is used at LHC energies. The production of kaons and lambda particles is studied in terms of the mean multiplicity in p-p collisions at energies ranging from 4 to 26 GeV. We find that both HRG model and the used event generators, EPOS 1.99 and EPOSlhc, can describe the particle ratios very well. Additionally, the freeze-out parameters are estimated for different collision systems, such as p-p and Pb-Pb, at LHC energies using both models.

scholarly journals Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

2014 ◽  
Vol 14 (19) ◽  
pp. 27195-27231
Author(s):  
C. R. MacIntosh ◽  
K. P. Shine ◽  
W. J. Collins
Keyword(s):  
Radiative Forcing ◽  
Transport Model ◽  
Task Force ◽  
Mean Field ◽  
Model Averaging ◽  
Chemical Transport Model ◽  
Ensemble Mean ◽  
The Mean ◽  
The Individual ◽  
The Impact

Abstract. Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOC and CO. When these ozone changes are used to calculate radiative forcing (RF) (and climate metrics such as the global warming potential (GWP) and global temperature potential (GTP)) there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane lifetime) changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in 4 regions (East Asia, Europe, North America and South Asia). We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOC and 2% for NOx. Differences of up to 60% for NOx 7% for VOC and 3% for CO are introduced into the 20 year GWP as a result of the exponential decay terms, with similar values for the 20 years GTP. However, estimates of the SD calculated from the ensemble-mean input fields (where the SD at each point on the model grid is added to or subtracted from the mean field) are almost always substantially larger in RF, GWP and GTP metrics than the true SD, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. We find that the effect is generally most marked for the case of NOx emissions, where the net effect is a smaller residual of terms of opposing signs. For example, the SD for the 20 year GWP is two to three times larger using the ensemble-mean fields than using the individual models to calculate the RF. Hence, while the average of multi-model fields are appropriate for calculating mean RF, GWP and GTP, they are not a reliable method for calculating the uncertainty in these fields, and in general overestimate the uncertainty.

scholarly journals Directed Flow in Microscopic Models in Relativistic A+A Collisions

Universe ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 69 ◽  
Author(s):  
Larissa Bravina ◽  
Yurii Kvasiuk ◽  
Sergey Sivoklokov ◽  
Oleksandr Vitiuk ◽  
Evgeny Zabrodin
Keyword(s):  
Relativistic Quantum ◽  
Mean Field ◽  
String Model ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Quantum Molecular Dynamics ◽  
Transport Models ◽  
Directed Flow ◽  
Ion Collisions ◽  
Microscopic Models

Evolution of directed flow of charged particles produced in relativistic heavy-ion collisions at energies 4 ≤ s ≤ 19.6 GeV is considered within two microscopic transport models, ultra-relativistic quantum molecular dynamics (UrQMD) and quark-gluon string model (QGSM). In both models, the directed flow of protons changes its sign at midrapidity from antiflow to normal flow with decreasing energy of collisions, whereas the flows of mesons and antiprotons remain antiflow-oriented. For lighter colliding systems, such as Cu+Cu or S+S, changing of the proton directed flow occurs at lower bombarding energies and for more central topologies compared to a heavy Au+Au system. The differences can be explained by dissimilar production zones of different hadrons and by the influence of spectators. Directed flows of most abundant hadronic species at midrapidity are found to be formed within t = 10–12 fm/c after the beginning of nuclear collision. The influence of hard and soft mean-field potentials on the directed flow is also studied.

scholarly journals Isospin Effects on Subthreshold Particle Production

2019 ◽  
Vol 14 ◽  
pp. 7
Author(s):  
T. Gaitanos ◽  
G. Ferini ◽  
M. Colonna ◽  
M. Di Toro ◽  
H. H. Wolter
Keyword(s):  
Particle Production ◽  
Transport Model ◽  
Mean Field ◽  
Heavy Ion ◽  
Production Data ◽  
Collision Term ◽  
Relativistic Mean Field ◽  
Ion Collisions ◽  
Dependent Part ◽  
Asymmetric Matter

The production/absorption rate of particles in compressed and heated asymmetric matter is studied using a Relativistic Mean Field (RMF) transport model with an isospin dependent collision term. We show that the K+/K° ratio reflects the isospin effects on the production rates just because of the large sensitivity around the threshold. The results are very promising with respect to the possibility of a direct link between particle production data in exotic Heavy Ion Collisions (HIC) and the isospin dependent part of the Equation of State (EoS) at high baryon densities.

Sign in / Sign up

Export Citation Format

Share Document