CGC, QCD Saturation and RHIC data (Kharzeev-Levin-McLerran-Nardi point of view)

This is the talk given at the Workshop:"Focus on Multiplicitioes", Bari, Italy, 17-19 June,2004.. In this talk, we are going to discuss ion-ion and deuteron - nucleus RHIC data and show that they support, if not more, the idea of the new QCD phase: colour glass condensate with saturated parton density. .Comment: 26 pages with 33 figure

Bulk properties and flow

In this report, I summarize the experimental results on {\bf bulk properties and flow} presented at Quark Matter 2004. It is organized in four sections: 1) Initial condition and stopping; 2) Particle spectra and freeze-outs; 3) Anisotropic flow; 4) Outlook for future measurements.Comment: 10 pages, 4 figures, "Rapporteur-Conference Highlights", Quark Matter 2004, Oakland, January 11-1

System size, energy, centrality and pseudorapidity dependence of charged-particle density in Au+Au and Cu+Cu collisions at RHIC

Charged particle pseudorapidity distributions are presented from the PHOBOS experiment at RHIC, measured in Au+Au and Cu+Cu collisions at sqrt{s_NN}=19.6, 22.4, 62.4, 130 and 200 GeV, as a function of collision centrality. The presentation includes the recently analyzed Cu+Cu data at 22.4 GeV. The measurements were made by the same detector setup over a broad range in pseudorapidity, |eta|<5.4, allowing for a reliable systematic study of particle production as a function of energy, centrality and system size. Comparing Cu+Cu and Au+Au results, we find that the total number of produced charged particles and the overall shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants, N_part. Detailed comparisons reveal that the matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of eta is better for the same N_part/2A value than for the same N_part value, where A denotes the mass number. In other words, it is the geometry of the nuclear overlap zone, rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence.Comment: 5 pages, 4 figures. Presented at the 20th International Conference on Nucleus-Nucleus Collisions (Quark Matter 2008), Jaipur, Rajasthan, India, 4-10 February 200

The Landscape of Particle Production: Results from PHOBOS

Recent results from the PHOBOS experiment at RHIC are presented, both from Au+Au collisions from the 2001 run and p+p and d+Au collisions from 2003. The centrality dependence of the total charged particle multiplicity in p+p and d+Au show features, such as Npart-scaling and limiting fragmentation, similar to p+A collisions at lower energies. Multiparticle physics in Au+Au is found to be local in (pseudo)rapidity, both when observed by HBT correlations and by forward-backward pseudorapidity correlations. The shape of elliptic flow in Au+Au, measured over the full range of pseudorapidity, appears to have a very weak centrality dependence. Identified particle ratios in d+Au reactions show little difference between the shape of proton and anti-proton spectra, while the absolute yields show an approximate m_T scaling.Comment: 8 Pages, 11 Figures, Plenary talk at Quark Matter 2004, Oakland, CA, January 11-18, 200

Pseudorapidity Distributions of Charged Particles in d + Au and p + p Collisions at sNN\sqrt{s_{_{NN}}} = 200GeV

The measured pseudorapidity distributions of primary charged particles are presented for d + Au and p + p collisions at ${\sqrt{s_{_{NN}}} =}$ 200 GeV over a wide pseudorapidity range of ${\rm \mid \eta \mid \le}$ 5.4. The results for d + Au collisions are presented for minimum-bias events and as a function of collision centrality. The measurements for p + p collisions are shown for minimum-bias events. The ratio of the charged particle multiplicity in d + Au and p + A collisions relative to that for inelastic p + p collisions is found to depend only on ${}$, and it is remarkably independent of collision energy and system mass. The deuteron and gold fragmentation regions in d + Au collisions are in good agreement with proton nucleus data at lower energies.Comment: 4 pages, 3 figures. To appear in the proceedings of Seventeenth International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California from January 11-17, 2004. Submitted to Journal of Physics G: Nuclear and Particle Physic

Rapidity and k_T dependence of HBT correlations in Au+Au collisions at 200 GeV with PHOBOS

Two-particle correlations of identical charged pion pairs from Au+Au collisions at sqrt(s_NN) = 200 GeV were measured by the PHOBOS experiment at RHIC. Data for the most central (0--15%) events were analyzed with Bertsch-Pratt (BP) and Yano-Koonin-Podgoretskii (YKP) parameterizations using pairs with rapidities of 0.4 < y < 1.3 and transverse momenta 0.1 < k_T < 1.4 GeV/c. The Bertsch-Pratt radii decrease as a function of pair transverse momentum. The pair rapidity Y_pipi roughly scales with the source rapidity Y_YKP, indicating strong dynamical correlations.Comment: 5 pages, 2 figures. To appear in the proceedings of Seventeenth International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California from January 11-17, 2004. Submitted to Journal of Physics G: Nuclear and Particle Physic

Scaling properties in bulk and pT_{\rm T}-dependent particle production near midrapidity in relativistic heavy ion collisions

The centrality dependence of the midrapidity charged-particle multiplicity density ($|\eta|$$<$1) is presented for Au+Au and Cu+Cu collisions at RHIC over a broad range of collision energies. The multiplicity measured in the Cu+Cu system is found to be similar to that measured in the Au+Au system, for an equivalent N$_{\rm part}$, with the observed factorization in energy and centrality still persistent in the smaller Cu+Cu system. The extent of the similarities observed for bulk particle production is tested by a comparative analysis of the inclusive transverse momentum distributions for Au+Au and Cu+Cu collisions near midrapidity. It is found that, within the uncertainties of the data, the ratio of yields between the various energies for both Au+Au and Cu+Cu systems are similar and constant with centrality, both in the bulk yields as well as a function of p$_{\rm T}$, up to at least 4 GeV/$c$. The effects of multiple nucleon collisions that strongly increase with centrality and energy appear to only play a minor role in bulk and intermediate transverse momentum particle production.Comment: Submitted for publication in Phys. Rev. C, 5 pages, 3 figure

Thermal Dileptons at LHC

We predict dilepton invariant-mass spectra for central 5.5 ATeV Pb-Pb collisions at LHC. Hadronic emission in the low-mass region is calculated using in-medium spectral functions of light vector mesons within hadronic many-body theory. In the intermediate-mass region thermal radiation from the Quark-Gluon Plasma, evaluated perturbatively with hard-thermal loop corrections, takes over. An important source over the entire mass range are decays of correlated open-charm hadrons, rendering the nuclear modification of charm and bottom spectra a critical ingredient.Comment: 2 pages, 2 figures, contributed to Workshop on Heavy Ion Collisions at the LHC: Last Call for Predictions, Geneva, Switzerland, 14 May - 8 Jun 2007 v2: acknowledgment include