scholarly journals The Evolution-Dominated Hydrodynamic Model and the Pseudorapidity Distributions in High Energy Physics

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Z. J. Jiang ◽  
H. L. Zhang ◽  
J. Wang ◽  
K. Ma

By taking into account the effects of leading particles, we discuss the pseudorapidity distributions of the charged particles produced in high energy heavy ion collisions in the context of evolution-dominated hydrodynamic model. The leading particles are supposed to have a Gaussian rapidity distribution normalized to the number of participants. A comparison is made between the theoretical results and the experimental measurements performed by BRAHMS and PHOBOS Collaboration at BNL-RHIC in Au-Au and Cu-Cu collisions atsNN=200 GeV and by ALICE Collaboration at CERN-LHC in Pb-Pb collisions atsNN=2.76 TeV.

2013 ◽  
Vol 22 (09) ◽  
pp. 1350069 ◽  
Author(s):  
ZHIJIN JIANG ◽  
QINGGUANG LI ◽  
GUANXIANG JIANG

By using the revised Landau hydrodynamic model and taking into account the effect of leading particles, we discuss the pseudorapidity distributions of produced charged particles in high energy heavy-ion collisions. The charged particles resulted from the freeze-out of the matter produced in collisions possess the Gaussian-like rapidity distributions. The leading particles are assumed having the rapidity distributions of the Gaussian form with the normalization constant being equal to the number of participants, which can be figured out in theory. It is found that the results from the revised Landau hydrodynamic model together with the contributions from leading particles are well consistent with the experimental data carried out by BNL-RHIC-PHOBOS Collaboration in different centrality Au + Au collisions at energies of [Formula: see text], 130 and 62.4 GeV , respectively.


Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 126
Author(s):  
Andrey Seryakov

The phase diagram of the strongly interacting matter is the main research subject for different current and future experiments in high-energy physics. System size and energy scan programs aim to find a possible critical point. One of such programs was accomplished by the fixed-target NA61/SHINE experiment in 2018. It includes six beam energies and six colliding systems: p + p, Be + Be, Ar + Sc, Xe + La, Pb + Pb and p + Pb. In this study, we discuss how the efficiency of centrality selection by forward spectators influences multiplicity and fluctuation measures and how this influence depends on the size of colliding systems. We use SHIELD and EPOS Monte-Carlo (MC) generators along with the wounded nucleon model, introduce a probability to lose a forward spectator and spectator energy loss. We show that for light colliding systems such as Be or Li even a small inefficiency in centrality selection has a dramatic impact on multiplicity scaled variance. Conversely, heavy systems such as Ar + Sc are much less prone to the effect.


2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Z. J. Jiang ◽  
Dongfang Xu ◽  
Yan Huang

In heavy ion collisions, charged particles come from two parts: the hot and dense matter and the leading particles. In this paper, the hot and dense matter is assumed to expand according to the hydrodynamic model including phase transition and decouples into particles via the prescription of Cooper-Frye. The leading particles are as usual supposed to have Gaussian rapidity distributions with the number equaling that of participants. The investigations of this paper show that, unlike low energy situations, the leading particles are essential in describing the pseudorapidity distributions of charged particles produced in high energy heavy ion collisions. This might be due to the different transparencies of nuclei at different energies.


2009 ◽  
Vol 20 (11) ◽  
pp. 1817-1825 ◽  
Author(s):  
EL-SAYED El-DAHSHAN ◽  
AMR RADI ◽  
MAHMOUD Y. El-BAKRY

High Energy Physics (HEP), due to the vast and complex data expected from current and future experiments, is in need of powerful and efficient techniques for various analysis tasks. Genetic Programing (GP) is a powerful technique that can be used such complex tasks. In this paper, Genetic programing is used for modeling the functions that describe the pseudo-rapidity distribution of the shower particles for 12 C , 16 O , 28 Si and 32 S on nuclear emulsion and also to predict the distributions that are not present in the training set and matched them effectively. The proposed method shows a better fitting with experimental data. The GP prediction results prove a strong presence modeling in heavy ion collisions.


1999 ◽  
Vol 77 (4) ◽  
pp. 313-318 ◽  
Author(s):  
F -H Liu ◽  
Y A Panebratsev

The pseudorapidity distribution of relativistic singly charged particles produced in high-energy heavy-ion collisions is described by the thermalized cylinder picture. The calculated results are in agreement with the experimental data of lead-induced interactions at 158A GeV/c. PACS Nos.:25.75.-q and 25.75.Dw


2015 ◽  
Vol 2015 ◽  
pp. 1-23 ◽  
Author(s):  
Li-Na Gao ◽  
Fu-Hu Liu

We propose a new revised Landau hydrodynamic model to study systematically the pseudorapidity distributions of charged particles produced in heavy ion collisions over an energy range from a few GeV to a few TeV per nucleon pair. The interacting system is divided into three sources, namely, the central, target, and projectile sources, respectively. The large central source is described by the Landau hydrodynamic model and further revised by the contributions of the small target/projectile sources. The modeling results are in agreement with the available experimental data at relativistic heavy ion collider, large hadron collider, and other energies for different centralities. The value of square speed of sound parameter in different collisions has been extracted by us from the widths of rapidity distributions. Our results show that, in heavy ion collisions at energies of the two colliders, the central source undergoes a phase transition from hadronic gas to quark-gluon plasma liquid phase; meanwhile, the target/projectile sources remain in the state of hadronic gas. The present work confirms that the quark-gluon plasma is of liquid type rather than being of a gas type.


Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 122 ◽  
Author(s):  
Keming Shen ◽  
Gergely Gábor Barnaföldi ◽  
Tamás Sándor Biró

We investigate how the non-extensive approach works in high-energy physics. Transverse momentum ( p T ) spectra of several hadrons are fitted by various non-extensive momentum distributions and by the Boltzmann–Gibbs statistics. It is shown that some non-extensive distributions can be transferred one into another. We find explicit hadron mass and center-of-mass energy scaling both in the temperature and in the non-extensive parameter, q, in proton–proton and heavy-ion collisions. We find that the temperature depends linearly, but the Tsallis q follows a logarithmic dependence on the collision energy in proton–proton collisions. In the nucleus–nucleus collisions, on the other hand, T and q correlate linearly, as was predicted in our previous work.


2012 ◽  
Vol 21 (01) ◽  
pp. 1250002 ◽  
Author(s):  
ZHIJIN JIANG ◽  
YUFEN SUN ◽  
QINGGUANG LI

We present the pseudorapidity distributions of the charged particles in nucleus–nucleus collisions as the function of beam energy and impact parameter through weighted superposition of the pseudorapidity distributions in the effective binary nucleon–nucleon collisions. We then analyze with the theoretical model the experimental measurements carried out by BNL-RHIC-PHOBOS Collaboration in Au + Au collisions at [Formula: see text], 130, 62.4 and 19.6 GeV. The model has only two free parameters and the theoretical results favor the experimental measurements well.


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