European Graduate School

Complex Systems of
Hadrons and Nuclei

Copenhagen - Giessen - Helsinki - Jyväskylä

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Lecture Week on The Physics of Hadrons
and Ultrarelativistic Heavy Ion Collisions

Jyväskylä, 9 - 14 August 2004

The lectures are arranged as part of the Jyväskylä Summer School . Registration is done via the application form of the school, by indicating participation in the course 'PH1'. Participants from Giessen and Copenhagen should in the 'Description' box state that they participate in the framework of the European Graduate School. No CV or other details are then required, and the category of accomodation will be chosen by the organisers. Graduate school participants may also (at their own expense) register for courses at the summer school taking place on 16 - 27 August.



Lecture notes

Steven Heppelmann Penn State University, USA: Proton Spin

From the days when Einstein and Bohr debated the meaning of quantum mechanics, the connection between quantum theory and observation has been a source of controversy. Spin measurements, even gedanken measurements, have played a pivotal role in clarifying the controversial issues. Developing the connection between QCD theory and hadronic measurement has been a great challenge. While the role of spin in the fundamental QCD interaction is clearly defined, the connection between the theory and observation has been slow to emerge. Emphasis on making these measurements and explaining the results in a QCD based framework is only now becoming an experimental priority. It is from this perspective that I will discuss the historical and recent measurements of spin dependent proton cross sections with emphasis on upcoming measurements to be made at Brookhaven lab.


Paul Hoyer University of Helsinki: Developments in PQCD applications

The structure of QCD bound states, the hadrons, is poorly understood. Nearly all the proton mass arises from quark and gluon interactions, yet the mechanism for this remains a conceptual enigma in QCD. Hard inclusive processes such as deeply inelastic lepton scattering have long allowed a precise description of longitudinal momentum distributions of single quarks and gluons. Equally rigorous perturbative methods have more recently been developed for deeply virtual exclusive processes such as Compton scattering and meson production. These allow new insights, including a 3-dimensional localisation of partons and their spin inside hadrons, and have triggered mutually stimulating developments in experiment and theory.


Pasi Huovinen Helsinki Institute of Physics: Hydrodynamics for Relativistic Heavy Ion Collisions

The description of the expansion stage of ultrarelativistic heavy-ion collision when the produced partons/hadrons keep interacting is a notoriously difficult many-body problem. However, the expansion stage can be described surprisingly well using simple ideal fluid hydrodynamics. In these lectures I give an introduction to the basic concepts of hydrodynamics as applied to relativistic heavy ion collisions. I also compare the hydrodynamical results with recent data obtained at the RHIC collider and show what kind of collective behaviour can be seen in the data.


James Ritman University of Giessen, Germany: Hadron Physics at the GSI Future Facility

The laboratory for heavy ion research GSI in Darmstadt Germany is planning a major upgrade of its experimental facilities. This approved project will bring GSI to the beam intensity frontier, allowing unsurpassed opportunities for new experiments. Two major directions in the field of hadron physics will be addressed at this new facility: 1) Relativistic heavy ion collisions near the charm production threshold provide a unique opportunity to probe a region of the nuclear phase diagram with very high net baryon density and moderate temperatures. 2) Secondary antiproton beams with unprecedented intensity and quality will allow fundemental questions in hadron physics such as quark confinementand and the origin of hadronic masses to be investigated. The physics programs and the progress towards designing and constructing state of the art detector apparatus for these experiments will be discussed.


Jussi Timonen University of Jyväskylä: Nonequilibrium dynamics: From paper burning to traffic jams

Nonequilibrium systems often display scaling properties which are similar to those in continuous phase transitions, i.e. those at a critical point. Following the analogy, it appears that these scaling properties can be classified into a limited number of 'universality classes'. The prototype nonequilibrium system, or universality class, is the one related to the Kardar-Parisi-Zhang (KPZ) equation, which is a stochastic nonlinear partial differential equation. The scaling properties of the KPZ equation in 1+1 dimensions are by now well understood. It has however been quite difficult to find experimental systems which would satisfy these properties: the scaling exponents e.g. seem to vary in a fairly wide range. It has been shown recently that slow-combustion fronts in paper indeed display KPZ scaling. It has also been possible to demonstrate in this particular system why the apparent scaling properties have varied: noise that typically appears in natural systems is not uncorrelated white noise, and because of their large natural fluctuations extensive averaging is needed before the true stationary behaviour becomes evident. There are still some open questions related for example to fronts in inhomogeneous systems, which are not fully understood. To this end it has been instructive to analyse the properties of asymmetric simple exclusion processes (ASEP), which have been shown to have scaling in the KPZ universality class. In fact there is an operator transformation which maps one problem to the other. On the other hand ASEP models have been used as simple models for traffic flows as they display queueing transitions of the type of traffic jams. A brief overview of these topics will be given in the lecture.


Ivan Vitev Iowa State University, USA: Parton energy loss in ultrarelativistic heavy ion collisions

The success of the high energy nuclear physics program at RHIC and the anticipated heavy ion program at the LHC have stimulated exciting new developments in the QCD multiple collision theory. Among these, recent insights into the medium-induced radiative energy loss of quarks and gluons penetrating dense QCD matter stand out. Improved perturbative methods to the computation of this dominant nuclear modification to inclusive large transverse momentum hadroproduction have been able to provide quantitative description of existing data.