• Heavy-ion reaction modeling, Freeze-out
  The main purpose of high energy nuclear physics is to reveal the properties of the fundamental interactions between the elementary constituents of nuclear matter. The hope is to reach conditions such that protons and neutrons melt into a soup of equilibrated quarks and gluons, and the so called Quark Gluon Plasma (QGP) would form. A similar situation might have existed in the very early stages of the Universe just after the Big Bang. The goal of the heavy ion programs now taking place at the Relativistic Heavy Ion Collider (RHIC) in Brookhaven and the Large Hadron Collider (LHC) at CERN is to study the properties of the QGP, as well as of critical phenomena associated with chiral symmetry breaking and confinement. The QGP, should be created at the very beginning of the heavy ion collisions. Thus, by the end of the reaction, all the QGP is washed away and instead an intense shower of different particles with different momenta is detected. Freeze-out describes the last stage of the heavy ion collision, when particles do not interact anymore, the momentum distribution stops varying, and the particles freely stream towards the detectors. Freeze-out models allow the evaluation of two-particle correlation data, transverse-, longitudinal-, radial-, and cylindrical- flow analyzes, transverse momentum and transverse mass spectra and many other observables. There are many different theoretical solutions to the freeze-out problem. Frequently, these approaches are oversimplified to the extent that conservation of energy and momentum is violated. Thus, we should keep in mind that only detailed comparison to experiments can judge how realistic a model is.
• Disoriented Chiral Condensates
  A very promising order parameter based possible observable for the QGP, is the so called Disoriented Chiral Condensate (DCC), which if created shows up in fluctuations of neutral to charged pion ratio. DCC was first introduced by Rajagopal and Wilczek. They argued that for a second order chiral phase transition, the chiral condensate can become temporarily disoriented during the non-equilibrium conditions encountered in heavy ion collisions. The spectrum of the emitted pions by a relaxing DCC domain may be very different from the one corresponding to hadronic processes, i.e. we will see many neutral pions accompanied by a few charged pions or vice versa. These type of features were already observed in cosmic ray collisions and are known as the Centauro and anti-Centauro events. Thus, DCC might provide a very distinct signal which would be extremely hard to explain based just on hadronic processes without a phase transition. The problem is that DCC pions are low momentum pions, and the background of thermal pions makes the experimental observation of the DCC signal very difficult or even impossible.
• Grid Computing
  The term "grid computing" suggests a computing paradigm similar to an electric power grid - a variety of resources contribute power into a shared "pool" for many consumers to access on an as needed basis. The Grid could be defined as a hardware and software infrastructure that provides dependable, consistent, pervasive and inexpensive access to high-end computational resources.

  The leading grid software packages today are Eurogrid(UNICORE) and Globus.

  Open Grid Services Architecture (OGSA) is an open standard at the base of all of these future grid enhancements. OGSA will standardize the grid interfaces that will be used by the new schedulers, autonomic computing agents, and any number of other services yet to be developed for the grid. It will make it easier to assemble the best products from various vendors, increasing the overall value of grid computing. More information about OGSA can be obtained at http://www.globus.org/ogsa.