Event-by-event fluctuations and the QGP

We discuss the physics underlying event-by-event fluctuations in relativistic heavy ion collisions. We will emphasize how the fluctuations of particle ratios can be utilized to explore the properties of the matter created in these collisions. In particular, we will argue that the fluctutions of the ratio of positively over negatively charged particles may serve as a unique signature for the Quark Gluon Plasma.Comment: Proceedings Quark Matter 2001, Stony Brook, NY January 200

Gravitational radiation from elastic particle scattering in models with extra dimensions

In this paper we derive a formula for the energy loss due to elastic N to N particle scattering in models with extra dimensions that are compactified on a radius R. In contrast to a previous derivation we also calculate additional terms that are suppressed by factors of frequency over compactification radius. In the limit of a large compactification radius R those terms vanish and the standard result for the non compactified case is recovered.Comment: 17 page

Event-by-event fluctuations of the charged particle ratio from non-equilibrium transport theory

The event by event fluctuations of the ratio of positively to negatively charged hadrons are predicted within the UrQMD model. Corrections for finite acceptance and finite net charge are derived. These corrections are relevant to compare experimental data and transport model results to previous predictions. The calculated fluctuations at RHIC and SPS energies are shown to be compatible with a hadron gas. Thus, deviating by a factor of 3 from the predictions for a thermalized quark-gluon plasma.Comment: This paper clarifies the previous predictions of Jeon and Koch (hep-ph/0003168) and addresses issues raised in hep-ph/0006023. 2 Figures, 10pp, uses RevTe

Core-corona separation in the UrQMD hybrid model

We employ the UrQMD transport + hydrodynamics hybrid model to estimate the effects of a separation of the hot equilibrated core and the dilute corona created in high energy heavy ion collisions. It is shown that the fraction of the system which can be regarded as an equilibrated fireball changes over a wide range of energies. This has an impact especially on strange particle abundancies. We show that such a core corona separation allows to improve the description of strange particle ratios and flow as a function of beam energy as well as strange particle yields as a function of centrality.Comment: 10 pages, 11 figures, version accepted by PR

Signatures of a minimal length scale in high precision experiments

We discuss modifications of the gyromagnetic moment of electrons and muons due to a minimal length scale combined with a modified fundamental scale $M_f$. First-order deviations from the theoretical standard model value for $g-2$ due to these String Theory-motivated effects are derived. A constraint of $M_f>577 GeV$ for the new fundamental scale is given.Comment: Proceedings of the Nuclear Physics Winter Meeting 2004, Bormio, Ital

Resonance Production in RHIC Collisions

Results of resonance particle production measured at RHIC in $\sqrt{s_{\rm NN}} =$ 200 GeV Au+Au collisions are compared to measurements in p+p and d+Au collisions in order to verify the existence of an extended hardronically interacting medium. Yield and momentum distributions of resonances maybe modified during the fireball lifetime due to resonance decay and the subsequent rescattering of their decay daughters as well as the regeneration of resonances from their decay products. Modified momentum spectra in heavy ion collisions may change the nuclear modification factor R$_{\rm AA}$. The influence on the elliptic flow v$_{2}$ due to late regeneration of resonances is discussed.Comment: 6 pages, 6 figures, Proceedings of the 22st Winter Workshop on Nuclear Dynamics, San Diago, California, 12-18 March, 200