Linear Extrapolation of Ultrarelativistic Nucleon-Nucleon Scattering to Nucleus-Nucleus Collisions

We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: all the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: it is a baseline linear extrapolation of ultrarelativistic nucleon-nucleon scattering to heavy ion collisions.Comment: 37 pages, 15 figures, LaTeX, uses rotating.st

Charge Transfer Fluctuations as a Signal for QGP

In this work, the charge transfer fluctuation which was previously used for $pp$ collisions is proposed for relativistic heavy-ion collisions as a QGP probe. We propose the appearance of a local minimum at midrapidity for the charge transfer fluctuation as a signal for a QGP. Within a two-component neutral cluster model, we demonstrate that the charge transfer fluctuation can detect the presence of a QGP as well as the size of the QGP in the rapidity space. We also show that the forward-backward correlation of multiplicity can be a similarly good measure of the presence of a QGP. Further, we show that the previously proposed net charge fluctuation is sensitive to the existence of the second phase only if the QGP phase occupies a large portion of the available rapidity space.Comment: 15 pages, 14 figures, to be submitte

MARTINI: An event generator for relativistic heavy-ion collisions

We introduce the Modular Algorithm for Relativistic Treatment of heavy IoN Interactions (MARTINI), a comprehensive event generator for the hard and penetrating probes in high energy nucleus-nucleus collisions. Its main components are a time evolution model for the soft background, PYTHIA 8.1 and the McGill-AMY parton evolution scheme including radiative as well as elastic processes. This allows us to generate full event configurations in the high p_T region that take into account thermal QCD and QED effects as well as effects of the evolving medium. We present results for the neutral pion nuclear modification factor in Au+Au collisions at RHIC as a function of p_T for different centralities, and also as a function of the angle with respect to the reaction plane for non-central collisions. Furthermore, we study the production of high transverse momentum photons incorporating a complete set of photon-production channels.Comment: 9 pages, 7 figures, some clarifications added, higher statistics included in the plots, corrected presentation of experimental data in Fig.