Proton/pion ratios and radial flow in pp and peripheral heavy ion collisions

The production of baryon and mesons in the RHIC heavy-ion experiments has received a lot of attention lately. Although not widely known, the pp data measured concurrently with heavy ion collisions do not find a convincing explanation in terms of simple models. We present the results of an afterburner to Pythia and Hijing event generators, simulating radial flow which seems to qualitatively explain the experimental results when applied to the pp collision data from RHIC at 200 GeV center-of-mass energy.Comment: 4 page, 5 figures. Prepared for X Mexican Workshop on Particles and Filed, Morelia Michoacan, November 7-17,2005. Referenced was corrected. Section 2, a sentence was modifie

Azimuthal Correlations in p-p collisions

We report the analysis of experimental azimuthal correlations measured by STAR in p-p collisions at $\sqrt{s_{NN}}$ = 200 GeV. We conclude that for a fit of data using Pythia event generator we need to include two values of $k_{T}$.Comment: 4 page, 3 figures. Prepared for X Mexican Workshop on Particles and Fields. Morelia Mich. Nov 7-12, 200

Heavy-Ion collisions at the LHC

An important part of the experimental programme at the Large Hadron Collider to be built at CERN will be devoted to the study of the phase transition to quark- gluon plasma in heavy-ion collisions. One detector, ALICE is devoted to the measurement of most observablescharacterizing the system formed in the collisions whilst the two p-p experiments, ATLAS and CMS, have capabilities to measure specific signals

ALICE: Status Report

Presently the ALICE collaboration has presented all but one TDR to the LHCC. The main features of the experiment will be reviewed and the performances of thedetectors outlined. (Abstract only available, full text will follow

Heavy-ion physics at LHC

In the following, we will concentrate on the unique physics aspects of the experimental programme on heavy-ion physics at LHC and the main characteristics of the experiments to cover it

What we have (not)learned from the ultrarelativistic heavy ion collisions

The field of ultrarelativistic heavy ion collisions is today a flourishing activity both on the experimental and on the theoretical side. Although the theoretical justifications to study these collisions was given already more than three decades ago and the experimental studies have a history of more than 25 years we are still very much in the dark as to the details of the processes and of the characteristics of the matter created in collisions. Increasing the energy of collisions has brought new insights but has also resulted with new challenges. In the present paper I will try from a personal perspective to report on the answers we have collected and on the problems we are faced with. The account is partial, taking into account that it is impossible to render justice to every aspect of the field.Comment: 12pages 3 figure

The broad away side of azimuthal correlations: 3 vs 2 final state particles in high energy nuclear collisions

In high energy heavy ion collisions at RHIC there are important aspects of the medium induced dynamics, that are still not well understood. In particular, there is a broadening and even a double hump structure of the away-side peak appearing in azimuthal correlation studies in Au+Au collisions which is absent in p+p collisions at the same energies. These features are already present but suppressed in p+p collisions: 2 to 3 parton processes produce such structures but are suppressed with respect to 2 to 2 processes. We argue that in A+A collisions the different geometry for the trajectories of 3 as opposed to 2 particles in the final state, together with the medium induced energy loss effects on the different cross sections, create a scenario that enhances processes with 3 particles in the final state, which gives on average this double hump structure.Comment: Prepared for the 5th International Workshop on High-pT Physics at LHC, ICN-UNAM, 27 Sep.-1 Oct, 201