122895317
Dependence of charged particle pseudorapidity distributions on centrality and energy in p(d)A collisions at high energies
The pseudorapidity distributions of charged particles produced in deuteron-gold (d-Au) and proton-emulsion (p-Em) collisions at high energies are studied in the framework of the two-cylinder model. The experimental results of nuclear reactions induced by protons and deuterons [p(d)A collisions] can be simply described by this model. The dependencies of parameter values on centrality for d-Au collisions and on nucleon-nucleon center-of-mass energy for p-Em collisions are obtained. The formula obtained by this model is a unified formula in the description of (pseudo)rapidity distributions of final-state particles produced in different interactions over an energy range from intermediate accelerator energy to ultrahigh cosmic-ray energy.
122540755
Particle production in Au–Au collisions at RHIC energies
Abstract An overlapping cylinder model (OCM) is introduced in this Letter which considers three components: the longitudinal flow, transverse flow and the temperature. A comparison of our model calculations in terms of pseudorapidity distributions with the most recent experiments is presented. To describe the experimental data at Relativistic Heavy Ion Collider (RHIC) energies ( s NN =130 and 200 GeV), a relative strong longitudinal flow and two partly overlapping cylinders are needed in the model. The difference between the different centrality events is described by the contribution of leading protons. The other parameter values do not depend on the centrality. The calculated results of the overlapping cylinder model are in agreement with the experimental data at the RHIC energies.
115903813
Angular Distributions of Target Fragments in Magnesium-Emulsion Collisions at High Energy
118607664
Singly and Doubly Charged Projectile Fragments in Nucleus-Emulsion Collisions at Dubna Energy in the Framework of the Multi-Source Model *
The multiplicity distributions of projectile fragments emitted in interactions of different nuclei with emulsion are studied by using a multi-source model. Our calculated results show that the projectile fragments can be described by the model and each source contributes an exponential distribution. As the weighted sum of the folding result of many exponential distributions, a multi-component Erlang distribution is used to describe the experimental data. The relationship between the height (or width) of the distribution and the mass of the incident projectile, as well as the dependence of projectile fragments on target groups, are investigated too.
122076971
ANGULAR DISTRIBUTIONS OF TARGET BLACK FRAGMENTS IN NUCLEUS NUCLEUS COLLISIONS AT HIGH ENERGY
The experimental results of space, azimuthal, and projected angular distributions of target black fragments produced in silicon-emulsion collisions at 4.5A GeV/c (the Dubna energy) are reported. A multi-source ideal gas model is suggested to describe the experimental angular distributions. The Monte Carlo calculated results are in agreement with the experimental data.
120712528
Alpha emission in krypton–emulsion collisions at 1.7A GeV
Abstract The multiplicity and transverse momentum distributions of alpha projectile fragments emitted in nucleus–nucleus collisions at high energies are investigated. The results calculated by the two-source model are in agreement with the experimental data of krypton–emulsion collisions at 1.7 A  GeV.
119211238
Directed flow of transported and non-transported protons in Au+Au collisions from UrQMD model
The directed flow of inclusive, transported and non-transported (including produced) protons, as well as antiprotons, has been studied in the framework of Ultra-Relativistic Quantum Molecular Dynamics approach (UrQMD model) for Au+Au collisions at √ sNN =7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV. The rapidity, centrality and energy dependence of directed flow for various proton groups are presented. It is found that the integrated directed flow decreases monotonically as a function of collision energy for √ sNN =11.5 GeV and beyond. However, the sign-change of directed flow of inclusive protons, seen in experimental data as a function of centrality and collision energy, can be explained by the competing effect of directed flow between transported and non-transported protons. Similarly the difference in directed flow between protons and antiprotons can be explained. Our study offers a conventional explanation on the cause of the v1 sign-change other than the antiflow component of protons alone which is argued to be linked to a phase transition.
122409394
Energy dependence of the v2-scaling and the QCD phase boundary
In high-energy nuclear collisions at RHIC ( = 60–200 GeV), quark coalescence has been suggested as one of the processes for hadronization. As a result, one observes a scaling in the elliptic flow parameter v2 and hadron-type dependence (within the 2 < pT < 5 GeV/c region) in the nuclear modification parameter RAA. On the other hand, in a given collision when the center of mass energy is not sufficiently high to create partonic matter, one would not expect the scaling in the final observed v2. Hence, the scaling provides us a sensitive tool for the search for the possible phase boundary in the hot/dense matter dominated by either partonic or hadronic degrees of freedom. In this paper, we will report the results from analyzing the energy dependence of v2 for identified hadrons from Au+Au collisions. Data from transport models are used in our analysis. In this model calculation, without the partonic coalescence the scaling in v2 is absent.
121546377
Dependences of charged particle pseudorapidity distributions on impact parameter and center-of-mass energy in nucleus–nucleus collisions at relativistic energies
The centrality and rapidity dependence of charged particles over a wide range of center-of-mass energy are analyzed. In this framework of participant-spectator model, the interacting system of nucleus–nucleus collisions at relativistic energies is divided into four parts (sources): target spectator, target participant, projectile participant and projectile spectator. Each source is treated by using a revised Landau model. The pseudorapidity distributions calculated by four-component Landau model are found to be in agreement with experimental data of the PHOBOS and ALICE collaborations. The distribution height is mainly determined by effective nucleon number and center-of-mass energy; and the distribution width being measured by the revised width in the Landau model and the sources rapidity shifts. Furthermore, we have found two empirical relations for projectile-participant and projectile-spectator (pseudo)rapidity as functions of the center-of-mass energy.
121716503
Recent Results on Hadron Spectroscopy and Charmonium from BESIII
pp mass threshold enhancement is studied using the data sample of J/ψ and y(2S) collected with BESIII detector in 2009. The enhancement is evident in J/ψ radiative decay, which is consistent with BESII results. No significance narrow enhancement is observed in ψ(2S) radiative decay. The structure of Xlpar;1835) is also confirmed in J/ψ = γηπ+π− at BESIII. The spin‐singlet P‐wave charmonium state hc(1P ) is studied at BESIII, the mass spectra recoiling against the π0 in the decay ψ(2S) = π0hc both in hc inclusive decay and in the final states with a tagged E1‐transition photon from hc → γηr are fitted to extract the number of hc signals.
56154903
Transverse Momentum Distributions of Final-State Particles Produced in Soft Excitation Process in High Energy Collisions
Transverse momentum distributions of final-state particles produced in soft process in proton-proton (pp) and nucleus-nucleus (AA) collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are studied by using a multisource thermal model. Each source in the model is treated as a relativistic and quantum ideal gas. Because the quantum effect can be neglected in investigation on the transverse momentum distribution in high energy collisions, we consider only the relativistic effect. The concerned distribution is finally described by the Boltzmann or two-component Boltzmann distribution. Our modeling results are in agreement with available experimental data.