The 2009 Europhysics Conference on High Energy Physics

Theoretical calculations locate the QCD critical end point at energies accessible at the CERN Super Proton Synchrotron (SPS). The QCD phase diagram (T - \mu_B) can be scanned by changing the energy and the size of the colliding system. Several observables were suggested to look for the critical point in ultra-relativistic heavy ion collisions. In the NA49 experiment we studied the energy...

Particle production in Pb-Pb collisions and hadron-induced reactions has been measured at a beam energy of 158 GeV per nucleon. The measurements provide full double differential coverage in a wide range of longitudinal and transverse momenta, including the central (``mid-rapidity'') area and extending far into the projectile fragmentation region. The resulting analysis shows the heavy-ion...

NA60 has measured dimuon production in In-In collisions at the CERN SPS at 158 GeV/nucleon, and in p-A at 158 and 400 GeV. Highlights from the results of NA60 include the first measurement of the rho spectral function in nuclear collision, the production of thermal muon pairs in the invariant mass region between the $\phi$ and the J/$\psi$, and the study of the J/$\psi$ suppression. In this...

We have considered a relativistically invariant quark coalescence model to predict hadronic resonance productions in heavy ion collisions. We extended our model - which has been applied earlier for strange and non-strange hadrons - to describe charmonium meson ratios, namely J/psi, Psi' and xi_c, at RHIC energies. In the applied quark coalescence model the widths of the produced mesons and...

Lattice QCD predicts that, above a certain critical energy density or temperature, strongly interacting matter undergoes a phase transition from the hadronic world to a quark-gluon plasma state, where the colored quarks and gluons are no longer bound to colorless hadrons. The suppression of quarkonium production in high-energy nuclear collisions is one of the most interesting signatures of...

Recent data in heavy ion collisions show suppression at high transverse momenta, which might be identified as the EMC effect. The influence of nuclear parton distribution functions (nPDFs) on high-$p_T$ hadron production in deuteron-gold $dAu$ collisions at RHIC was investigated using a pQCD-improved parton model and several different parameterizations of nuclear PDFs, including the...

The BRAHMS results on the proton-to-pion ratio pT-dependence in the RHIC range of baryo-chemical potential N. Katryńska, Z. Majka (for the BRAHMS Collaboration) BRAHMS measurement of proton-to-pion ratios in Au+Au and p+p at (s NN) ½ = 62.4 GeV and 200 GeV will be presented...

In the collisions of ultrarelativistic heavy ions the energy of the nuclei is released in a small volume leading to the creation of a hot and dense nuclear matter. The study of the particles produced from it gives the information on the conditions in the early stage of the collision and the evolution of the system. The PHOBOS experiment provides unique data on the particle production in...

High energy nucleus nucleus collisions produce extraordinarily hot and dense QCD matter which exhibits near-perfect fluid behavior and interacts strongly. This talk will present recent results from the PHENIX experiment at RHIC on the dynamical evolution of the medium and its response to high momentum probes. Their impact on our overall understanding of heavy-ion collisions will be discussed.

Recent 3+1D hydrodynamic calculations modeling the expansion of the dense matter created in Heavy-Ion collisions at RHIC energies are presented. Assuming a relatively early start up time of the collective expansion and a hard equation of state, we are able to reproduce particle spectra at different centralities and rapidities, elliptic flow as function pseudorapidity, HBT radii and directed...

The contribution presents a brief summary of the Gauge/Gravity approach to the study of hydrodynamic flow of the quark-gluon plasma formed in heavy-ion collisions, in a boost-invariant setting (Bjorken flow). Considering the ideal case of a supersymmetric Yang-Mills theory for which the AdS/CFT correspondence gives a precise form of the Gauge/Gravity duality, the properties of the strongly...