119190350
Kolmogorov-Smirnov test and its use for the identification of fireball fragmentation
We propose an application of the Kolmogorov-Smirnov test for rapidity distributions of individual events in ultrarelativistic heavy-ion collisions. The test is particularly suited to recognizing nonstatistical differences between the events. Thus when applied to a narrow centrality class it could indicate differences between events that would not be expected if all events evolved according to the same scenario. In particular, as an example we assume here a possible fragmentation of the fireball into smaller pieces at the quark/hadron phase transition. Quantitative studies are performed with a Monte Carlo model capable of simulating such a distribution of hadrons. We conclude that the Kolmogorov-Smirnov test is a very powerful tool for the identification of the fragmentation process.
16622057
The influence of bulk evolution models on heavy-quark phenomenology
We study the impact of different Quark-Gluon Plasma expansion scenarios in heavy-ion collisions on spectra and elliptic flow of heavy quarks. For identical heavy-quark transport coefficients relativistic Langevin simulations with different expansion scenarios can lead to appreciable variations in the calculated suppression and elliptic flow of the heavy-quark spectra, by up to a factor of two. A cross comparison with two sets of transport coefficients supports these findings, illustrating the importance of realistic expansion models for quantitative evaluations of heavy-quark observables in heavy-ion collisions. It also turns out that differences in freeze-out prescriptions and Langevin realizations play a significant role in these variations. Light-quark observables are essential in reducing the uncertainties associated with the bulk-matter evolution, even though uncertainties due to the freeze-out prescription persist.
17991173
The use of Kolmogorov-Smirnov test in event-by-event analysis
Abstract We propose to use the Kolmogorov-Smirnov test to uncover non-statistical differences between events created in heavy ion collisions within the same centrality class. The advantage of the method over other approaches which are currently in use, is that it is sensitive to any difference between the events and is not restricted to simple moments of the distribution of hadrons. The particular application examined here is the identification of the fireball decay due to spinodal fragmentation and/or sudden rise of the bulk viscosity.
122326383
THE INTERACTION OF ρ AND K+ MESONS WITH MATTER
We review in this contribution the information we can obtain from heavy-ion experiments about the interaction of mesons with matter. We demonstrate that the vector mesons seen in experiments come predominantly from low densities. Kaons offer a better opportunity but most of the presently available experimental observables do not allow to analyze separately the three essential unknown quantities: the kaon production cross-section in the medium, the K+N potential interaction at finite densities and temperatures and the kaon (elastic or charge exchange) rescattering cross-section in the medium. We propose a measurement which almost exclusively tests the K+N potential.
122683216
Resonance Multiplicities in a Hadron Transport Approach
In this article we focus on the multiplicities of resonances, ratios of resonant over non-resonant states and rescattering processes in heavy ion collisions. Therefore we utilize a hadron transport model (UrQMD vl.3). We find that rescattering of decay particles is of great importance when studying resonances in a hadronic medium.
118616628
Resonance Absorption and Regeneration in Relativistic Heavy Ion Collisions
The regeneration of hadronic resonances is discussed for heavy ion collisions at SPS and SIS-300 energies. The time evolutions of Delta, rho and phi resonances are investigated. Special emphasize is put on resonance regeneration after chemical freeze-out. The emission time spectra of experimentally detectable resonances are explored.
14401845
Coordinated NIR/mm observations of flare emission from Sagittarius A*
Context. We report on a successful, simultaneous observation and modelling of the millimeter (mm) to near-infrared (NIR) flare emission of the Sgr A* counterpart associated with the supermassive (4 × 10^6 M_☉) black hole at the Galactic centre (GC). We present a mm/sub-mm light curve of Sgr A* with one of the highest quality continuous time coverages. 
 
Aims. We study and model the physical processes giving rise to the variable emission of Sgr A*. 
 
Methods. Our non-relativistic modelling is based on simultaneous observations carried out in May 2007 and 2008, using the NACO adaptive optics (AO) instrument at the ESO's VLT and the mm telescope arrays CARMA in California, ATCA in Australia, and the 30 m IRAM telescope in Spain. We emphasize the importance of multi-wavelength simultaneous fitting as a tool for imposing adequate constraints on the flare modelling. We present a new method for obtaining concatenated light curves of the compact mm-source Sgr A* from single dish telescopes and interferometers in the presence of significant flux density contributions from an extended and only partially resolved source. 
 
Results. The observations detect flaring activity in both the mm domain and the NIR. Inspection and modelling of the light curves show that in the case of the flare event on 17 May 2007, the mm emission follows the NIR flare emission with a delay of 1.5±0.5 h. On 15 May 2007, the NIR flare emission is also followed by elevated mm-emission. We explain the flare emission delay by an adiabatic expansion of source components. For two other NIR flares, we can only provide an upper limit to any accompanying mm-emission of about 0.2 Jy. The derived physical quantities that describe the flare emission give a source component expansion speed of ν_(exp) ~ 0.005c–0.017c, source sizes of about one Schwarzschild radius, flux densities of a few Janskys, and spectral indices of α = 0.6 to 1.3. These source components peak in the THz regime. 
 
Conclusions. These parameters suggest that either the adiabatically expanding source components have a bulk motion greater than ν_(exp) or the expanding material contributes to a corona or disk, confined to the immediate surroundings of Sgr A*. Applying the flux density values or limits in the mm- and X-ray domain to the observed flare events constrains the turnover frequency of the synchrotron components that are on average not lower than about 1 THz, such that the optically thick peak flux densities at or below these turnover frequencies do not exceed, on average, about ~1 Jy.