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T. Csorgo

Publications and source records attributed to T. Csorgo.

At least 37 records · Page 2Linked to original sources
arXiv2010

Spectra, elliptic flow and azimuthally sensitive HBT radii from Buda-Lund model for sqrt(s(NN)) = 200 GeV Au+Au collisions

We present calculations of elliptic flow and azimuthal dependence of correlation radii in the ellipsoidally symmetric generalization of the Buda-Lund hydrodynamic model of hadron production in high-energy nuclear collisions. We compare them to data from RHIC by simultaneous fits to azimuthally integrated invariant spectra of pions, kaons and protons-antiprotons measured by PHENIX in Au+Au reactions at center of mass energy of 200 AGeV. STAR data were used for azimuthally sensitive two-particle correlation function radii and for the transverse momentum dependence of the elliptic flow parameter v2. We have found that the transverse flow is faster in the reaction plane then out of plane, which results in a reaction zone that gets slightly more elongated in-plane than out of plane. The model parameters extracted from the fits are shown and discussed.

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arXiv2010

U_A(1) Symmetry Restoration from an In-Medium eta' Mass Reduction in sqrt(s(NN)) = 200 GeV Au+Au Collisions

A reduction of the mass of the eta'(958) meson may signal restoration of the U_A(1) symmetry in a hot and dense hadronic matter, corresponding to the return of the 9th, "prodigal" Goldstone boson. We report on an analysis of a combined PHENIX and STAR data set on the intercept parameter of the two-pion Bose-Einstein correlation functions, as measuremed in sqrt(s(NN)) = 200 GeV Au + Au collisions at RHIC. To describe this combined PHENIX and STAR dataset, an in-medium eta' mass reduction of at least 200 MeV is needed, at the 99.9 % confidence level in a broad model class of resonance abundances.

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arXiv2010

Indirect observation of an in-medium eta' mass reduction in sqrt(s_{NN})=200 GeV Au+Au collisions

PHENIX and STAR data on the intercept parameter of the two-pion Bose-Einstein correlation functions in sqrt(s_{NN}) = 200 GeV Au+Au collisions are analyzed in terms of different models of hadronic multiplicities. To describe this combined PHENIX and STAR dataset, an in-medium eta' mass reduction of at least 200 MeV is needed, at the 99.9 % confidence level in the considered model class. Such a significant eta' mass modification may indicate the restoration of the U_A(1) symmetry in a hot and dense hadronic matter and the return of the 9th "prodigal" Goldstone boson.

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arXiv2010

Nuclear modification factors of phi mesons in d+Au, Cu+Cu and Au+Au collisions at sqrt(S_NN)=200 GeV

The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has performed systematic measurements of phi meson production in the K+K- decay channel at midrapidity in p+p, d+Au, Cu+Cu and Au+Au collisions at sqrt(S_NN)=200 GeV. Results are presented on the phi invariant yield and the nuclear modification factor R_AA for Au+Au and Cu+Cu, and R_dA for d+Au collisions, studied as a function of transverse momentum (1<p_T<7 GeV/c) and centrality. In central and mid-central Au+Au collisions, the R_AA of phi exhibits a suppression relative to expectations from binary scaled p+p results. The amount of suppression is smaller than that of the neutral pion and the eta meson in the intermediate p_T range (2--5 GeV/c); whereas at higher p_T the phi, pi^0, and eta show similar suppression. The baryon (protons and anti-protons) excess observed in central Au+Au collisions at intermediate p_T is not observed for the phi meson despite the similar mass of the proton and the phi. This suggests that the excess is linked to the number of constituent quarks rather than the hadron mass. The difference gradually disappears with decreasing centrality and for peripheral collisions the R_AA values for both particles are consistent with binary scaling. Cu+Cu collisions show the same yield and suppression as Au+Au collisions for the same number of N_part. The R_dA of phi shows no evidence for cold nuclear effects within uncertainties.

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arXiv2010

Detailed L3 measurements of Bose-Einstein correlations and a region of anti-correlations in hadronic Z^0 decays at LEP

L3 preliminary data of two-particle Bose-Einstein correlations are reported for hadronic Z^0 decays in e+e- annihilation at LEP. The invariant relative momentum Q is identified as the eigenvariable of the measured correlation function. Significant anti-correlations are observed in the Bose-Einstein correlation function in a broad region of 0.5 - 1.6 GeV with a minimum at Q close to 0.8 GeV. Absence of Bose-Einstein correlations is demonstrated in the region above Q >= 1.6 GeV. The effective source size is found to decrease with increasing value of the transverse mass of the pair, similarly to hadron-hadron and heavy ion reactions. These feautes and our data are described well by the non-thermal tau-model, which is based on strong space-time momentum-correlations.

hep-ex↗
arXiv2009

Critical Opalescence: An Optical Signature for a QCD Critical Point

Four possible scenarios are considered for a transition from a quark-gluon matter to hadronic matter, and their corresponding correlation signatures are discussed. Four criteria are highlighted for a definitive experimental search for a QCD critical point. An old-new experimental measure, the optical opacity (or its inverse the nuclear attenuation length) is determined, in terms of a combination of nuclear suppression factors and a measurement of the relevant fireball length scales. Length scale estimates using either the Hanbury Brown -- Twiss radii or that of the initial nuclear geometry for measurements of optical opacity with respect to the reaction plane yield, somewhat surprizingly, nearly the same nuclear attenuation lenght in 0-5 % most central 200 GeV Au+Au collisions, corresponding to 2.9 $\pm$ 0.3 fm. The necessity and the possibility of measuring critical exponents is also discussed in the context of determination of the universality class of the QCD critical point. Critical opalescence is proposed to locate such a critical point on the QCD phase diagram, corresponding to a maximum of optical opacity in heavy ion experiments.

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arXiv2009

Correlation Probes of a QCD Critical Point

Critical opalescence is a characteristic experimental signature of a second order phase transition in solid state physics. A new, experimentally accessible measure of opacity and of attenuation length in heavy ion reactions is suggested, as a combination of HBT radii and nuclear modification factors. This opacity is maximal when $\sqrt{s_{NN}}$, the system size and centrality correspond to the critical point of QCD. To characterize the phase transition at this critical point, the critical exponent of the correlation function can be determined by measuring the Lévy index of stability of the Bose-Einstein or HBT correlations. The exponent of the correlation length can be determined from fits to the multiplicity distribution in various pseudorapidity intervals, also as a function of colliding energy, system size, centrality and (chemical) freeze-out temperature. These two critical exponents determine the remaining four critical exponents and the universality class of this second order phase transition. As a control experiment, the determination of the critical exponent of the specific heat capacity is proposed, from event-by-event fluctuation measurements. To measure opacity precisely, well calibrated high transverse momentum probes are needed, such as given by the excitation function of $γ$ + jet correlation functions.

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arXiv2009

Bose-Einstein or HBT correlations in high energy reactions

Concepts of thermalization and hydrodynamical behavior are applied from time to time to e+e-, hadron+hadron and heavy ion collisions. These applications are scrutinized paying attention to particle multiplicities, spectra, and Bose-Einstein correlations in particular. Can hydrodynamics describe these data?

hep-ph↗
arXiv2008

Critical Exponents and Particle Multiplicity Distributions in High Energy Collisions

Data from the L3, Tasso, Opal and Delphi collaborations are analyzed in terms of a statistical model of high energy collisions. The model contains a power law critical exponent tau and Levy index alpha. These data are used to study values of tau and alpha. The very high multiplicity events in L3, Opal and Delphi are consistent with a model based on a Feynman-Wilson gas which has a tail exponent tau=3/2 and alpha=1/2.

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arXiv2008

Universal scaling of the elliptic flow data at RHIC

Recent PHOBOS measurements of the excitation function for the pseudo-rapidity dependence of elliptic flow in Au+Au collisions at RHIC, have posed a significant theoretical challenge. Here we show that these differential measurements, as well as the RHIC measurements on transverse momentum satisfy a universal scaling relation predicted by the Buda-Lund model, based on exact solutions of perfect fluid hydrodynamics. We also show that recently found transverse kinetic energy scaling of the elliptic flow is a special case of this universal scaling.

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arXiv2008

New exact solutions of relativistic hydrodynamics

A new class of simple and exact solutions of relativistic hydrodynamics is presented, and the consequences are explored in data analysis. The effects of longitudinal work and acceleration are taken into account in an advanced estimate of the initial energy density and the life-time of the reaction.

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arXiv2008

Search for Squeezed-Pair Correlations at RHIC

Squeezed correlations of particle-antiparticle pairs, also called Back-to-Back Correlations, are predicted to appear if the hadron masses are modified in the hot and dense hadronic medium formed in high energy nucleus-nucleus collisions. Although well-established theoretically, the squeezed-particle correlations have not yet been searched for experimentally in high energy hadronic or heavy ion collisions, clearly requiring optimized forms to experimentally search for this effect. Within a non-relativistic treatment developed earlier we show that one promising way to search for the BBC signal is to look into the squeezed correlation function of pairs of phi-mesons at RHIC energies, plotted in terms of the average momentum of the pair, K12=(k1+k2)/2. This variable's modulus, 2|K12|, is the non-relativistic limit of the variable Q_bbc, introduced herewith. The squeezing effects on the HBT correlation function are also discussed.

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arXiv2008

Parametrization of Bose-Einstein Correlations and Reconstruction of the Space-Time Evolution of Pion Production in e+e- Annihilation

A parametrization of the Bose-Einstein correlation function of pairs of identical pions produced in hadronic e+e- annihilation is proposed within the framework of a model (the tau-model) in which space-time and momentum space are very strongly correlated. Using information from the Bose-Einstein correlations as well as from single-pion spectra,it is then possible to reconstruct the space-time evolution of pion production.

hep-ph↗
arXiv2008

Kaon HBT radii from perfect fluid dynamics using the Buda-Lund model

In this paper we summarize the ellipsoidally symmetric Buda-Lund model's results on HBT radii. We calculate the Bose-Einstein correlation function from the model and derive formulas for the transverse momentum dependence of the correlation radii in the Bertsch-Pratt system of out, side and longitudinal directions. We show a comparison to $\sqrt{s_{\rm NN}}=200 GeV$ RHIC PHENIX two-pion correlation data and make prediction on the same observable for different particles.

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arXiv2007

Similar final states from different initial states using new exact solutions of relativistic hydrodynamics

We present exact, analytic and simple solutions of relativistic perfect fluid hydrodynamics. The solutions allow us to calculate the rapidity distribution of the particles produced at the freeze-out, and fit them to the measured rapidity distribution data. We also give an advanced estimation of the energy density reached in heavy ion collisions, and an improved estimation of the life-time of the reaction.

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arXiv2007

Detailed description of accelerating, simple solutions of relativistic perfect fluid hydrodynamics

In this paper we describe in full details a new family of recently found exact solutions of relativistic, perfect fluid dynamics. With an ansatz, which generalizes the well-known Hwa-Bjorken solution, we obtain a wide class of new exact, explicit and simple solutions, which have a remarkable advantage as compared to presently known exact and explicit solutions: they do not lack acceleration. They can be utilized for the description of the evolution of the matter created in high energy heavy ion collisions. Because these solutions are accelerating, they provide a more realistic picture than the well-known Hwa-Bjorken solution, and give more insight into the dynamics of the matter. We exploit this by giving an advanced simple estimation of the initial energy density of the produced matter in high energy collisions, which takes acceleration effects (i.e. the work done by the pressure and the modified change of the volume elements) into account. We also give an advanced estimation of the life-time of the reaction. Our new solutions can also be used to test numerical hydrodynamical codes reliably. In the end, we also give an exact, 1+1 dimensional, relativistic hydrodynamical solution, where the initial pressure and velocity profile is arbitrary, and we show that this general solution is stable for perturbations.

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arXiv2007

Multi-boson correlations using wave-packets II

We investigate the analytically solvable pion-laser model, and its generalization to arbitrary multiplicity distributions. Although this kind of extension of the model is possible, the pion laser model in its original form is unique: it is the only model in its class that has an analytic solution.

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