Two- and three-particle azimuthal correlations of high-pt charged hadrons in Pb-Au collisions at 158A GeV/c

Azimuthal correlations of hadrons with high transverse momenta serve as a measure to study the energy loss and the fragmentation pattern of jets emerging from hard parton-parton interactions in heavy ion collisions. Preliminary results from the CERES experiment on two- and three-particle correlations in central Pb-Au collisions are presented. A strongly non-Gaussian shape on the away-side of the two-particle correlation function is observed, indicating significant interactions of the emerging partons with the medium. Mechanisms like deflection of the initial partons or the evolution of a mach cone in the medium can lead to similar modifications of the jet structure on the away-side. An analysis based on three-particle correlations is presented which helps to shed light on the origin of the observed away-side pattern.Comment: 4 pages, 2 figures, contribution to the Quark Matter conference 200

Event-by-Event Fluctuations at 40, 80, and 158 AGeV/c in Pb+Au Collisions

Event-by-event fluctuations of mean pt and net charge in 40, 80, and 158 AGeV/c Pb+Au collisions are presented. The observed dynamical mean pt fluctuations in central events of about 1 % are very similar to results from RHIC. The centrality dependence of mean pt fluctuations at 158 AGeV/c shows a peculiar non-monotonic pattern with respect to the extrapolation from the fluctuations measured in p+p collisions. Dynamical net charge fluctuations smaller than the charge conservation limit are observed. After correction for charge conservation, the measured fluctuation signal in central events is comparable to RHIC results.Comment: 4 pages, 6 figures, proceedings of the Quark Matter 2004, in Oakland, USA, to be published in Journal of Physics G: Nuclear and Particle Physic

Transverse Momentum Spectra of Pions in Particle and Nuclear Collisions and Some Ratio-Behaviours: Towards A Combinational Approach

The nature of transverse momentum dependence of the inclusive cross-sections for secondary pions produced in high energy hadronic($PP$), hadronuclear($PA$) and nuclear($AA$) collisions has here been exhaustively investigated for a varied range of interactions in a unified way with the help of a master formula. This formula evolved from a new combination of the basic Hagedorn's model for particle(pion) production in PP scattering at ISR range of energies, a phenomenological approach proposed by Peitzmann for converting the results of $NN(PP)$ reactions to those for either $PA$ or $AA$ collisions, and a specific form of parametrization for mass number-dependence of the nuclear cross sections. This grand combination of models(GCM) is then applied to analyse the assorted extensive data on various high energy collisions. The nature of qualitative agreement between measurements and calculations on both the inclusive cross-sections for production of pions, and some ratios of them as well, is quite satisfactory. The modest successes that we achieve here in dealing with the massive data-sets are somewhat encouraging in view of the diversity of the reactions and the very wide range of interaction energies.Comment: 19 pages, 19 figure

Azimuthal anisotropies and initial-state fluctuations from SPS to LHC energies

The v(3) coefficient, obtained using the PbAu data from the CERES detector at the top SPS energy of root sNN = 17.3 GeV, is presented. The v(2) is measured over a pT range up to 100 GeV/c in PbPb collisions collected with the CMS detector. The v(2){2} of charged and strange particles emitted in pp collisions shows a mass ordering effect. The v(2){4} and v(2){6} are comparable to the v(2){2}, and thus supports the collective nature of the long-range correlations in high-multiplicity pp collisions at 13 TeV. Principle Component Analysis (PCA) of two-particle harmonics (V-n Delta) is studied in PbPb and high-multiplicity pPb collisions at the LHC. The factorization breaking of the V-n Delta can be attributed to the effect of initial-state fluctuations. Using a PCA, the V-n Delta are characterized through the leading and sub-leading modes. The leading modes are essentially equivalent to the v(n){2}. The sub-leading modes represent the largest sources of factorization breaking.23rd International Baldin Seminar on High Energy Physics Problems - Relativistic Nuclear Physics and Quantum Chromodynamics, Sep 19-24, 2016, Dubna, Russi

An Overview of Fluctuation and Correlation Results in Relativistic Heavy Ion Collisions

A great deal of recent data on event-by-event fluctuation and correlation measurements has been released by several experiments at the SPS and RHIC. Recent results on charge fluctuations, balance functions in pseudorapidity, and average transverse momentum fluctuations will be reviewed. The results will be compared to various model predictions after examining contributions to each observable from known physics processes.Comment: 8 pages, 3 figures. Contribution to the Proceedings of the 17th International Conference on Ultra Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California, 11-17 Jan 2004. Submitted to J.Phys.

Centrality and sNNDependenceofthe\sqrt{s_{NN}} Dependence of the dE_{T}/d\etaand and dN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity

The PHENIX experiment at RHIC has measured transverse energy and charged particle multiplicity at mid-rapidity in Au + Au collisions at $\sqrt{s_{NN}}$ = 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented results are compared to measurements from other RHIC experiments, and experiments at lower energies. The $\sqrt{s_{NN}}$ dependence of $dE_{T}/d\eta$ and $dN_{ch}/d\eta$ per pair of participants is consistent with logarithmic scaling for the most central events. The centrality dependence of $dE_{T}/d\eta$ and $dN_{ch}/d\eta$ is similar at all measured incident energies. At RHIC energies the ratio of transverse energy per charged particle was found independent of centrality and growing slowly with $\sqrt{s_{NN}}$. A survey of comparisons between the data and available theoretical models is also presented.Comment: Proccedings of the Workshop: Focus on Multiplcity at Bari, Italy, June 17-19,2004. To be submitted to the Jornal of Physics, "Conference series". Includes: 20 Pages, 15 figures, 3 Tables, 80 Referencie

Viscosity and the Soft Ridge at RHIC

Correlation studies exhibit a ridge-like feature in rapidity and azimuthal angle, with and without a jet trigger. We ask whether the feature in untriggered correlations can be a consequence of transverse flow and viscous diffusion.Comment: Proc. Quark Matter 2008, Jaipur, Indi