Renata Kopecna

Observables of non-equilibrium phase transition⋆

Abstract.A rapidly expanding fireball which undergoes first-order phase transition will supercool and proceed via spinodal decomposition. Hadrons are produced from the individual fragments as well as the left-over matter filling the space between them. Emission from fragments should be visible in rapidity correlations, particularly of protons. In addition to that, even within narrow centrality classes, rapidity distributions will be fluctuating from one event to another in case of fragmentation. This can be identified with the help of the Kolmogorov-Smirnov test. Finally, we present a method which allows to sort events with varying rapidity distributions, in such a way that events with similar rapidity histograms are grouped together.

Event Shape Sorting: selecting events with similar evolution

We present novel method for the organisation of events. The method is based on comparing event-by-event histograms of a chosen quantity Q that is measured for each particle in every event. The events are organised in such a way that those with similar shape of the Q-histograms end-up placed close to each other. We apply the method on histograms of azimuthal angle of the produced hadrons in ultrarelativsitic nuclear collisions. By selecting events with similar azimuthal shape of their hadron distribution one chooses events which are likely that they underwent similar evolution from the initial state to the freeze-out. Such events can more easily be compared to theoretical simulations where all conditions can be controlled. We illustrate the method on data simulated by the AMPT model.