Reconstructing the Source in Heavy Ion Collisions from Particle Interferometry

The preliminary CERN SPS NA49 Pb+Pb 158 GeV/A negative one- and two-particle spectra at mid-rapidity are consistent with a source of temperature 130 MeV, lifetime 9 fm/c, transverse flow 0.35, and a transverse geometric size which is twice as large as the cold Pb nucleus.Comment: Proceedings for Quark Matter 97; 4 pages, 2 eps-figure

Inviscid symmetry breaking with non-increasing energy

In a recent article, C. Bardos et. al. constructed weak solutions of the three-dimensional incompressible Euler equations which emerge from two-dimensional initial data yet become fully three-dimensional at positive times. They asked whether such symmetry-breaking solutions could also be constructed under the additional condition that they should have non-increasing energy. In this note, we give a positive answer to this question and show that such a construction is possible for a large class of initial data. We use convex integration techniques as developed by De Lellis-Sz\'ekelyhidi.Comment: To appear in C. R. Math. Acad. Sci. Pari

A remark on the constructibility of real root representations of quivers using universal extension functors

In this paper we consider the following question: Is it possible to construct all real root representations of a given quiver Q by using universal extension functors, starting with a real Schur representation? We give a concrete example answering this question negatively.Comment: 8 pages, shorter than older veriso

HOW EUROPEAN HISTORIANS IN THE NINETEENTH AND EARLY TWENTIETH CENTURIES TOLD THE HISTORY OF HUMAN MASS MIGRATIONS OR VÖLKERWANDERUNGEN

Historians’ interest in the history of human migrations is not limited to recent years. Migrations had already figured as explanatory factors in connection with cultural and historical change in the work of classical and ancient studies scholars of the late nineteenth and early twentieth centuries. In the writings of these scholars, migrations acted as historical landmarks or epochal thresholds and played a key role in the construction of geo‐historical areas. This model has been called “migrationism” and cannot be explained simply on the basis of the history of individual disciplines, but must be seen in its complex interaction with scientific and historical contexts. However, “migrationism” does not relate to fixed political and scientific positions or movements. For this reason, it cannot be explained adequately by using a historically or ideologically based approach. Relying on narratological approaches, this article examines migration narratives that historians of this period used to explain the rise and fall of ancient civilizations. Referring to contemporary historiographical representations of the ancient Near East, it distinguishes three main narratives that are still common today: narratives of foundation, narratives of destruction, and narratives of mixtures. In this sense, analyzing older migration narratives helps us to sharpen the critical view on the genealogy of our own views on the history—and present—of human migrations

Opportunities for Heavy Ion Physics at the Large Hadron Collider LHC

This talk discusses extrapolations to the LHC of several, apparently universal trends, seen in the data on relativistic nucleus-nucleus collisions up to RHIC energies. In the soft physics sector, such extrapolations to the LHC are typically at odds with LHC predictions of the dynamical models, advocated to underlie multi-particle production up to RHIC energies. I argue that due to this, LHC is likely to be a discovery machine not only in the hard, but also in the soft physics sector.Comment: Plenary talk given at Quark Matter 2006, Shanghai, China, 14-20 Nov 2006; to appear in the conference proceeding

Energy Loss of Hard Partons in Nuclear Matter

We report on recent calculations of the medium-induced gluon radiation off hard partons. The employed path-integral formalism reduces in limiting cases to the main ``jet quenching'' results of the existing literature. Moreover, it describes destructive interference effects between medium-independent and medium-induced radiation amplitudes. These affect the angular distribution and $L$-dependence of the medium-induced gluon bremsstrahlung spectrum significantly.Comment: 4 pages LaTeX, invited talk given at the 15th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (QM 2001), Long Island, New York, January 15 - 20, 200

Coulomb Final State Interactions for Gaussian Wave Packets

Two-particle like-sign and unlike-sign correlations including Coulomb final state interactions are calculated for Gaussian wave packets emitted from a Gaussian source. We show that the width of the wave packets can be fully absorbed into the spatial and momentum space widths of an effective emission function for plane wave states, and that Coulomb final state interaction effects are sensitive only to the latter, but not to the wave packet width itself. Results from analytical and numerical calculations are compared with recently published work by other authors.Comment: 10 pages Latex, 2 eps-figure

Introductory Overview of Quark Matter 2012

The two arguably most generic phenomena seen in ultra-relativistic heavy ion collisions are the flow of essentially all soft hadronic observables and the quenching of essentially all hard hadronic observables. Limiting the discussion to these two classes of phenomena, I review what can be said so far about the properties of hot and dense QCD matter from the heavy ion programs at RHIC and at the LHC, and I discuss the opportunities for further progress in the coming years.Comment: 8 pages, write-up of plenary talk at Quark Matter 2012 in Washington, to appear in the QM12 conference proceeding

From Leading Hadron Suppression to Jet Quenching at RHIC and at the LHC

In nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC), one generically observes a strong medium-induced suppression of high-pT hadron production. This suppression is accounted for in models which assume a significant medium-induced radiative energy loss of high-pT parent partons produced in the collision. How can we further test the microscopic dynamics conjectured to underly this abundant high-pT phenomenon? What can we learn about the dynamics of parton fragmentation, and what can we learn about the properties of the medium which modifies it ? Given that inelastic parton scattering is expected to be the dominant source of partonic equilibration processes, can we use hard processes as an experimentally well-controlled window into QCD non-equilibrium dynamics ? Here I review what has been achieved so far, and which novel opportunities open up with higher luminosity at RHIC, and with the wider kinematical range accessible soon at the LHC.Comment: 8 pages Latex, 4 eps-figures, contribution to the proceedings of the "Hard Probes 2004" conference in Ericeira, Portugal, November 4-10, 200