17,193 research outputs found
PACIAE 2.0: An updated parton and hadron cascade model (program) for the relativistic nuclear collisions
We have updated the parton and hadron cascade model PACIAE for the
relativistic nuclear collisions, from based on JETSET 6.4 and PYTHIA 5.7 to
based on PYTHIA 6.4, and renamed as PACIAE 2.0. The main physics concerning the
stages of the parton initiation, parton rescattering, hadronization, and hadron
rescattering were discussed. The structures of the programs were briefly
explained. In addition, some calculated examples were compared with the
experimental data. It turns out that this model (program) works well.Comment: 23 pages, 7 figure
Charged multiplicity density and number of participant nucleons in relativistic nuclear collisions
The energy and centrality dependences of charged particle pseudorapidity
density in relativistic nuclear collisions were studied using a hadron and
string cascade model, JPCIAE. Both the relativistic experimental
data and the PHOBOS and PHENIX data at RHIC energy could be fairly
reproduced within the framework of JPCIAE model and without retuning the model
parameters. The predictions for collisions at the LHC energy were also
given. We computed the participant nucleon distributions using different
methods. It was found that the number of participant nucleons is not a well
defined variable both experimentally and theoretically. Thus it may be
inappropriate to use the charged particle pseudorapidity density per
participant pair as a function of the number of participant nucleons for
distinguishing various theoretical models. A discussion for the effect of
different definitions in nuclear radius (diffused or sharp) was given.Comment: 15 pages, 7 figure
Net charge fluctuation and string fragmentation
We present simulation results of net charge fluctuation in collisions
at =130 GeV from a dynamic model, JPCIAE. The calculations are
done for the quark-gluon phase before hadronization, the pion gas, the
resonance pion gas from and decays and so on. The simulations
of the charge fluctuation show that the discrepancy exists between the dynamic
model and the thermal model for a pion gas and a resonance pion gas from
and decays while the simulated charge fluctuation of the quark-gluon
phase is close to the thermal model prediction. JPCIAE results of net charge
fluctuation in the hardonic phase are nearly 4-5 times larger than one for the
quark-gluon phase, which implies that the charge fluctuation in the quark-gluon
phase may not survive the hadronization (string fragmentation) as implemented
in JPCIAE.Comment: 9 pages, 3 figure
Mean Field Effects In The Quark-Gluon Plasma
A transport model based on the mean free path approach for an interacting
meson system at finite temperatures is discussed. A transition to a quark gluon
plasma is included within the framework of the MIT bag model. The results
obtained compare very well with Lattice QCD calculations when we include a mean
field in the QGP phase due to the Debye color screening. In particular the
cross over to the QGP at about 175 MeV temperature is nicely reproduced. We
also discuss a possible scenario for hadronization which is especially
important for temperatures below the QGP phase transition
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
in the relativistic nuclear collisions at RHIC and LHC energies. With randomly
sampling the transverse momentum and components of the particles
generated in string fragmentation on the circumference of an ellipse instead of
circle originally, the calculated charged particle and
fairly reproduce the corresponding experimental data in the Au+Au/Pb+Pb
collisions at =0.2/2.76 TeV. In addition, the charged particle
and in the p+p collisions at =7 TeV as well as
in the p+Au/p+Pb collisions at =0.2/5.02 TeV are predicted.Comment: 7 pages, 5 figure
The evolution of ontology in AEC: A two-decade synthesis, application domains, and future directions
Ontologies play a pivotal role in knowledge representation, particularly beneficial for the Architecture, Engineering, and Construction (AEC) sector due to its inherent data diversity and intricacy. Despite the growing interest in ontology and data integration research, especially with the advent of knowledge graphs and digital twins, a noticeable lack of consolidated academic synthesis still needs to be addressed. This review paper aims to bridge that gap, meticulously analysing 142 journal articles from 2000 to 2021 on the application of ontologies in the AEC sector. The research is segmented through systematic evaluation into ten application domains within the construction realm- process, cost, operation/maintenance, health/safety, sustainability, monitoring/control, intelligent cities, heritage building information modelling (HBIM), compliance, and miscellaneous. This categorisation aids in pinpointing ontologies suitable for various research objectives. Furthermore, the paper highlights prevalent limitations within current ontology studies in the AEC sector. It offers strategic recommendations, presenting a well-defined path for future research to address these gaps
Energy and centrality dependences of charged multiplicity density in relativistic nuclear collisions
Using a hadron and string cascade model, JPCIAE, the energy and centrality
dependences of charged particle pseudorapidity density in relativistic nuclear
collisions were studied. Within the framework of this model, both the
relativistic experimental data and the PHOBOS and PHENIX
data at =130 GeV could be reproduced fairly well without retuning
the model parameters. The predictions for full RHIC energy collisions
and for collisions at the ALICE energy were given. Participant nucleon
distributions were calculated based on different methods. It was found that the
number of participant nucleons, for distinguishing various theoretical models.Comment: 10 pages, 4 figures, submitted to Phy. Lett.
- …