Modelling correlations in heavy ion collisions

Modelling correlations in heavy ion collisions is reviewed from model independent characterization of the two-particle correlations to Buda-Lund hydro model fits to correlations and spectra in Au + Au collisions at sqrt{s}=130 AGeV at RHIC.Comment: 6 pages, 2 figures, talk given at XXXI International Symposium on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. See http://202.114.35.18

The reconstructed final state of Au + Au collisions from PHENIX and STAR data at sqrt{s}=130 AGeV - indication for quark deconfinement at RHIC

The final state of Au + Au collisions at sqrt{s}=130 AGeV at RHIC has been reconstructed within the framework of the Buda-Lund hydrodynamical model, by performing a simultaneous fit to final data on two-particle Bose-Einstein correlations of the STAR and PHENIX Collaborations, and final identified single particle spectra as measured by the PHENIX Collaboration. The results indicate a strongly three-dimensional expansion with a four-velocity field that is almost a spherically symmetric Hubble flow. We find large transverse geometrical source sizes, R_G = 9.8 +- 1.2 fm, a relatively short mean freeze-out time of tau0 = 6.1 +- 0.3 fm/c and a short duration of particle emission, Delta_tau = 0.02 +- 1.5 fm/c. Most strikingly, we find an indication for a hot central part or the hydrodynamically evolving core, characterized by a central temperature of T0 = 202 +- 13 MeV, that is close to (or even above) the deconfinement temperature of the quark-hadron phase transition. The best fit indicates a cold surface temperature of T_s = 110 +- 16 MeV. When the possibility of the hot center is excluded, the confidence level of the fit decreases from 28.9 % to 1.2 %. Predictions are made for the rapidity dependence of the slope parameters, for the transverse mass dependence of the rapidity-width of the single-particle spectra, and for the transverse velocity dependence of the non-indentical particle correlations.Comment: 18 pages, 3 eps figures, based on the talk of A. Ster at the Budapest 02 workshop on Quark and Hadron Dynamics, budapest1.st

Transmission parameters of the 2001 foot and mouth epidemic in Great Britain.

Despite intensive ongoing research, key aspects of the spatial-temporal evolution of the 2001 foot and mouth disease (FMD) epidemic in Great Britain (GB) remain unexplained. Here we develop a Markov Chain Monte Carlo (MCMC) method for estimating epidemiological parameters of the 2001 outbreak for a range of simple transmission models. We make the simplifying assumption that infectious farms were completely observed in 2001, equivalent to assuming that farms that were proactively culled but not diagnosed with FMD were not infectious, even if some were infected. We estimate how transmission parameters varied through time, highlighting the impact of the control measures on the progression of the epidemic. We demonstrate statistically significant evidence for assortative contact patterns between animals of the same species. Predictive risk maps of the transmission potential in different geographic areas of GB are presented for the fitted models

The reconstructed final state of Pb + Pb 158 AGeV reactions from spectra and correlation data of NA49, NA44 and WA98

The final state of Pb + Pb reactions at CERN SPS has been reconstructed with the Buda-Lund hydro model, by performing a simultaneous fit to NA49, NA44 and WA98 data on particle correlations and spectra.Comment: 4 pages, LaTeX, 4 EPS figures, 1 table; presented at QM9

An indication for deconfinement in Au+Au collisions at RHIC

We present simultaneous, quality fits to final BRAHMS, PHENIX, PHOBOS and STAR data on particle spectra and two-particle Bose-Einstein or HBT correlations as measured in Au+Au collisions at $\sqrt{s_{NN}} = 130$ GeV. Using the Buda-Lund hydro model, the best fit is achieved when the most central 1/8th of the particle emitting volume is superheated to $T > T_c =170$ MeV. In contrast, we find no indication for such a hot central region in a similar analysis of Pb+Pb data at CERN SPS.Comment: 6 pages, 2 figures, 1 table, presented by A. Ster at the XXXIIIth International Symposium on Multiparticle Dynamics, Cracow, Poland, Sept. 200

Understanding the rapidity dependence of the elliptic flow and the HBT radii at RHIC

The pseudo-rapidity dependence of the elliptic flow at various excitation energies measured by the PHOBOS Collaboration in Au+Au collisions at RHIC is one of the surprising results that has not been explained before in terms of hydrodynamical models. Here we show that these data are in agreement with theoretical predictions and satisfy the universal scaling relation predicted by the Buda-Lund hydrodynamical model, based on exact solutions of perfect fluid hydrodynamics. We also show a theoretical prediction on the rapidity and transverse momentum scaling of the HBT radii measured in heavy ion collisions, based on the Buda-Lund model.Comment: 6 pages, 2 figures, proceedings contribution for M. Csanad's talk at the Workshop on Particle Correlations and Femtoscopy 2005, Kromeri

A hint at quark deconfinement in 200 GeV Au+Au data at RHIC

We give the emission function of the axially symmetric Buda-Lund hydro model and present its simultaneous, high quality fits to identified particle spectra, two-particle Bose-Einstein or HBT correlations and charged particle pseudorapidity distributions as measured by BRAHMS and PHENIX in 0-30 % central, \sqrt{s_{\NN}} = 200 GeV Au+Au collisions at RHIC. The best fit is achieved when the most central region of the particle emitting volume is superheated to $T_0 = 200 \pm 9$ MeV $\ge T_c =172 \pm 3$ MeV, a preliminary, 3 $\sigma$ effect.Comment: 10 pages, 3 figures, talk of A. Ster at the 2nd Warsaw Meeting on Correlations and Resonances in HIC, see http://hirg.if.pw.edu.pl/en/meeting/oct2003/talks/csorgo/Ster.pp

A Duality Based 2-Approximation Algorithm for Maximum Agreement Forest

We give a 2-approximation algorithm for the Maximum Agreement Forest problem on two rooted binary trees. This NP-hard problem has been studied extensively in the past two decades, since it can be used to compute the Subtree Prune-and-Regraft (SPR) distance between two phylogenetic trees. Our result improves on the very recent 2.5-approximation algorithm due to Shi, Feng, You and Wang (2015). Our algorithm is the first approximation algorithm for this problem that uses LP duality in its analysis