Review of structures in the energy dependence of hadronic observables

The energy dependence of various hadronic observables is reviewed. The study of their evolution from AGS over SPS to the highest RHIC energy reveals interesting features, which might locate a possible onset of deconfinement. These observables include transverse spectra of different particle types and their total multiplicities, as well as elliptic flow. In this context especially the observation of a maximum of the strangeness to pion ratio is of particular interest, since on one hand it has been predicted as a signal for the onset of deconfinement but on the other hand also statistical model calculations exhibit qualitatively similar structures. The sharpness of these features is however not reproduced by hadronic scenarios. The significance of these structures will be discussed in this contribution. Other observables, such as radius parameters from Bose-Einstein correlations, on the other hand do not exhibit any structure in their energy dependence

Three-body bound states in a harmonic waveguide with cylindrical symmetry

Highly-elongated quasi-one-dimensional cold atom samples have been studied extensively over the past years experimentally and theoretically. This work determines the energy spectrum of two identical fermions and a third distinguishable particle as functions of the mass ratio $\kappa$ and the free-space $s$-wave scattering length $a_{3\text{D}}$ between the identical fermions and the distinguishable third particle in a cylindrically symmetric waveguide whose symmetry axis is chosen to be along the $z$-axis. We focus on the regime where the mass of the identical fermions is equal to or larger than that of the third distinguishable particle. Our theoretical framework accounts explicitly for the motion along the transverse confinement direction. In the regime where excitations in the transverse direction are absent (i.e., for states with projection quantum number $M_{\text{rel}}=0$), we determine the binding energies for states with odd parity in $z$. These full three-dimensional energies deviate significantly from those obtained within a strictly one-dimensional framework when the $s$-wave scattering length is of the order of or smaller than the oscillator length in the confinement direction. If transverse excitations are present, we predict the existence of a new class of universal three-body bound states with $|M_{\text{rel}}|=1$ and positive parity in $z$. These bound states arise on the positive $s$-wave scattering length side if the mass ratio $\kappa$ is sufficiently large. Implications of our results for ongoing cold atom experiments are discussed.Comment: 9 figure

Open Questions in the Understanding of Strangeness Production in HIC -- Experiment Perspective

Open questions concerning strangeness production in heavy-ion collisions are discussed with a focus on the experimental aspects. The open points are presented in the context of recent measurements.Comment: Proceedings for the Strange Quark Matter 2017 conference in Utrecht, Netherland

Strangeness Production at the SPS

Systematic studies on the production of strange hyperons and the phi meson as a function of beam energy and system size performed by the NA49 collaboration are discussed. Hadronic transport models fail to describe the production of multi strange particles (Xi, Omega), while statistical models are generally in good agreement to the measured particle yields at all energies. The system size dependence is well reproduced by the core-corona approach. New data on K*(892) production are presented. The yields of these short-lived resonances are significantly below the statistical model expectation. This is in line with the interpretation that the measurable yields are reduced due to rescattering of their decay products inside the fireball.Comment: Proceedings to the ISMD09 Conference. 5 pages, 6 figure

Recent results from the NA49 experiment

Recent results of the NA49 collaboration are presented. Transverse mass spectra as well as total multiplicities of identified particles are discussed. The study of their evolution from AGS over SPS to the highest RHIC energy reveals a couple of interesting features. These include a sudden change in the energy dependence of the mt-spectra and of the yields of strange hadrons around 30A GeV. Additionally, new results on particle production at high-pt for Pb+Pb collsions at 158A GeV, as well as on the v2 of L, are discussed

Coordination and Learning with a Partial Language

This paper explores how efficiency promotes the use of structure in language. It starts from the premise that one of language’s central characteristics is to provide a means for saying novel things about novel circumstances, its creativity. It is reasonable to expect that in a rich and changing environment, language will be incomplete. This encourages reliance on structure. It is shown how creative language use emerges form common knowledge structures, even if those structures are consistent with an a priori absence of a common language. ZUSAMMENFASSUNG - (Koordination und Lernen mit einer Partialsprache) In diesem Beitrag wird die Anwendung von Strukturen in einer Sprache aus Effizienzsicht begründet. Der Artikel geht davon aus, daß eines der wichtigsten Merkmale der Sprache in ihrer Kreativität zu sehen ist, d. h. als Mittel, um Neues über neue Sachverhalte auszusagen. Es ist deshalb zu erwarten, daß in einer vielfältigen und sich verändernden Umwelt die Sprache unvollständig bleiben wird. Dies fördert die Anwendung von Strukturen. Es wird gezeigt, wie die kreative Sprachanwendung aus allgemeinen Wissensstrukturen entsteht, auch dann, wenn diese Strukturen a priori noch keine gemeinsame Sprache bilden.Language; Coordination; Optimal Learning; Common Knowledge

Learning, Experimentation, and Long-Run Behavior in Games

This paper investigates a class of population-learning dynamics. In every period agents either adopt a best reply to the current distribution of actual play, or a best reply to a sample, taken with replacement, from the distribution of intended play (the strategies adopted at the end of last period), or they are inactive. If sampling with replacement and being inactive have strictly positive probability, these dynamics converge globally to minimal curb sets in the absence of mistakes. For two-player i x j-games, i; j .le. 3; the same result holds even if only best responding to actual play and being inactive have positive probability. If players make mistakes in the implementation of their strategies, these dynamics select among minimal curb sets .