Azimuthal distributions of final-state particles and fragments and transverse structure of emission source in high-energy nucleus-nucleus collisions

The azimuthal distributions of final-state particles and fragments produced in high-energy nucleus-nucleus collisions are described by a modified multisource ideal gas model which contains the expansions and movements of the emission sources. The transverse structures of the sources are given in the transverse plane by momentum components Px and Py, and described by parameters in the model. The results of the azimuthal distributions, calculated by the Monte Carlo method, are in good agreement with the experimental data in nucleus-nucleus collisions at high energies.

Oscillations of moments in high-energy nucleus-nucleus collisions

The definitions of density function and moment of multiplicity distribution are introduced,and the method of moment analysis in e+ e- and proton-proton (pp) interactions is extended into nu-cleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and cal-culate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hq on incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e + e-, pp and AA inter-actions, and the comparison and analysis are carried out between experimental data and QCD predic-tion. The latest results are given in this paper.

Nucleus-Nucleus Effects in Fully Differential Cross Sections for Energetic C6++He Collisions with Small Momentum Transfer

The modified Coulomb-Born approximation with and without the internuclear interaction （MCB-NN and MCB） is used to calculate the fully differential cross sections （FDCS） for the single ionization of helium by lOO MeV/amu C6＋ impact. The effects of the internuclear interaction on the FDCS are examined in geometries. The results are compared with experimental data and theoretical predictions from a three-body distorted-wave （3DW） model and a time-dependent close-coupling model. It is shown that the present MCB-NN results are in good agreement with the experiments in the scattering plane and the MCB results qualitatively reproduce the experimental structure outside the scattering plane. In particular, the MCB theory predicts the ＇double-peak＇ structure in the perpendicular plane.

Multiplicity Distribution of Evaporated Fragments in Relativistic Nucleus-Nucleus Collisions

The multiplicity distribtuion of evaporated fragments in relativistic nucleus-nucleus collisions are discussed.The calculated results are in agreement with the exper-imental data in the energy range from 3.7 to 200 GeV/N.

Emission of Protons in Inelastic Nucleus-Nucleus Collisions at High Energy

Based on the participant-spectator model and the analysis of particle producing proce-ss, the rapidity distribution and the noninvariant center-of-mass energy spectrum of final pro-tons produced in inelastic nucleus-nucleus collisions are studied.

Longitudinal Extension and Pseudorapidity Distributions of Shower Particles in Relativistic Nucleus-Nucleus Collisions

The longitudinal extension of interacting system in relativistic nucleus-nucleus colli-sions is considered.The pseudorapidity distribution of shower particles is described by the ther-realized cylinder picture.The calculated results are in agreement with the experimental data inthe incident energy region from 10~1 to 10~5 GeV/u.

A Calculation of Excitation Energy of Spectator in Relativistic Nucleus-Nucleus Collisions

The excited degree of spectator in relativistic nucleus-nucleus collisions is investig-ated.The heat of friction due to the relative motion beween the participant and the spectatorand the superfluous surface energy due to the spectator deformation are calculated.

Transverse momentum and transverse mass distributions of charged hadrons produced in Au-Au collisions at high energies

The transverse momentum distribution and the transverse mass distribution of charged hadrons produced in nucleus nucleus collisions at high energies are described by using a two-cylinder model. The results calculated by the model are compared and found to be in agreement with the experimental data of the STAR and E895 Collaborations, measured in A^Au collisions at the relativistic heavy ion collider （RHIC） and alternating-gradient synchrotron （AGS） energies, respectively. In the energy range concerned, the excitation degree of emission source close to the central axis of cylinders increases obviously with the collision centrality and incident energy increasing, but it does not show any obvious change with the increase of the （pseudo）rapidity in central collisions. The excitation degree of emission source close to the side-surface of cylinders does not show any obvious change with the collision centrality, the （pseudo）rapidity, and the incident energy increasing.

Study of Wavelet Methodology and Chaotic Behavior of Produced Particles in Different Phase Spaces of Relativistic Heavy Ion Collisions

We applied the wavelet methodology for our earlier published research work of the chaotic behavior so called multiplicity fluctuations of secondary charged particles produced during the nucleus-nucleus (A-A) collisions at an energy of the order of ≈ 409 GeV in a new fashion. We illustrated the wavelet coherency in a relation of chaotic behavior for above said data of secondary charged pions in different phase spaces of collisions such as: η-space, φ-space (in one dimension) and ηφ-space (in two dimensions) respectively. We have shown the changes in the wavelet coherence when there are different values of two parameters “q” and “p”. We discussed our new results for the comparison purpose and findings were in the good agreements.

Multiplicity distribution of final-state particles and different contributions of related sources in nucleus-nucleus collisions at high energies

The final state particle multiplicity distributions in high-energy nucleus-nucleus collisions are described by two different sub-distributions contributed by a single nucleon. The Monte Carlo calculated results from the two sub-distributions and the participant-spectator model are compared and found to be in agreement with the experimental data of Au-Au collisions at √s= 130 AGeV and Pb-Pb collisions at 158 AGeV.

Pronounced Fluctuations of Target Fragments in Forward Hemisphere Only in Ultra Relativistic Nuclear Collision

Dynamical fluctuation of target evaporated black particles is investigated in both forward and backward hemispheres within the framework of multi-dimensional factorial moment methodology using the brilliant concept of the Hurst exponent. We analyse the black particles emitted in ^32S-AgBr interactions at 200AGeV and it is evident that the dynamical fluctuation in the backward hemisphere is self-affine. In the forward hemisphere, dynamical fluctuation is self-similar but not self-affine. However, study indicates that the fluctuation in the forward hemisphere is more pronounced than that in backward hemisphere.

Azimuthal correlations of hadrons and fragments in nucleus-nucleus collisions

Two-particle （two-fragment） azimuthal correlation functions are studied by using a simple formula which describes uniformly azimuthal distributions of final-state charged particles and nuclear fragments. This formula is obtained in the framework of a multi-source thermal model （or multi-source ideal gas model）. The calculated results are compared and found to be in agreement with the experimental data of charged hadrons and nuclear fragments in nucleus-nucleus collisions at intermediate and high energies.

Multiparticle azimuthal correlations in central nucleus-nucleus collisions at high energy

Multiparticle azimuthal correlations in central nucleus-nucleus collisions at high energy are described by a simple formula. The calculated results are in agreement with the experimental data of carbon and oxygen induced interactions at Dubna energy. The comparison between the calculated results and experimental data shows that particles are emitted isotropically in the rest frame of the emission sources, and the emission sources have movements in momentum space.

Centrality dependence of pT spectra for identified hadrons in Au+Au and Cu+Cu collisions at (~SNN)^(1/2)=200 GeV

The centrality dependence of transverse momentum spectra for identified hadrons at midrapidityin Au＋Au collisions at √sNN=200GeV is systematically studied in a quark combination model. The PTspectra of π^±, K^±, p（p） and A（A） in different centrality bins and the nuclear modification factors （Rcp） forthese hadrons are calculated. The centrality dependence of the average collective transverse velocity （β （r）） for the hot and dense quark matter is obtained in Au＋Au collisions, and it is applied to a relative smallerCu＋Cu collision system. The centrality dependence of PT spectra and the Rcp for π^0, Ks^0 and A in Cu-bCucollisions at √sNN = 200 GeV are well described. The results show that （β （r）〉is only a function of the numberof participants Npart and it is independent of the collision system.

Final-State Energy Spectrum in Nuclear Electromagnetic Dissociation Process

The final-state energy spectrum in the electromagnetic dissociation is calculated by asimple method.The final-state energy curves obtained from the calculation are in agreementwith the experimental data of 28Si into p+27Al at an energy of 14.6 GeV/u.

Suggesting a Very Simple Experiment Designed to Detect Tachyons

Production of tachyons in, among other things, air showers would be in accordance with predictions of general relativity. Some such tachyons would travel with a precisely determined speed, almost equal to 5c/3 relative to the earth, and would be registered high above the region of creation of air showers, e.g. on board of a satellite. A very simple experiment designed to detect these tachyons is outlined here. Brief justification to search for tachyons is also given.

Some Important Features of Relativistic Charged Particles Produced in ³²S-Emulsion Interactions at 200 AGeV/c

An attempt has been made to study the multiplicity, angular and pseudo rapidity distributions of relativistic charged particles emerging from the interactions between sulphur and nuclear emulsion nuclei at 200 GeV/nucleon. The distributions from 200 AGeV are compared to the corresponding distributions from the predictions of Monte Carlo code FRITIOF samples. The pseudo rapidity distributions in different Nh-intervals translate to the target fragmentation region with increasing target mass. Finally, the scaling of multiplicity distributions of shower particles successfully describes the consequences of KNO scaling.

Unimolecular Dissociation of H⁺<sub style="margin-left:-6px;">2n+1</sub>Hydrogen Clusters: Measured Cross Sections and Theoretically Calculated Rate Constants

In this paper, we studied the process of dissociation unimolecular of the evaporation of H+2n+1 hydrogen clusters according to size, using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The rate constants k(E) were determined with the use of statistical theory of unimolecular reactions using various approximations. In our work, we used the products frequencies instead of transitions frequencies in the calculation of unimolecular dissociation rates obtained by three models RRKM. The agreement between the experimental cross section ratio and calculated rate ratio with direct count approximation seems to be reasonable.

Pion transverse-momentum spectrum, elliptic flow, and Hanbury-Brown-Twiss interferometry in a viscous granular source model

We examine the evolution of quark-gluon plasma（QGP） droplets with viscous hydrodynamics and analyze the pion transverse-momentum spectrum, elliptic flow, and Hanbury-Brown-Twiss（HBT） interferometry in a granular source model consisting of viscous QGP droplets. The shear viscosity of the QGP droplet speeds up and slows down the droplet evolution in the central and peripheral regions of the droplet, respectively. The effect of the bulk viscosity on the evolution is negligible. Although there are viscous effects on the droplet evolution, the pion momentum spectrum and elliptic flow change little for granular sources with and without viscosity. On the other hand,the influence of viscosity on HBT radius Rout is considerable. It makes Rout decrease in the granular source model.We determine the model parameters of granular sources using the experimental data of pion transverse-momentum spectrum, elliptic flow, and HBT radii together, and investigate the effects of viscosity on the model parameters. The results indicate that the granular source model may reproduce the experimental data of pion transverse-momentum spectrum, elliptic flow, and HBT radii in heavy-ion collisions of Au-Au at√s（NN）=200 GeV and Pb-Pb at√s（NN） =2.76 Te V in different centrality intervals. The viscosity of the droplet leads to an increase in the initial droplet radius and a decrease of the source shell parameter in the granular source model.