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B. Lorstad

Publications and source records attributed to B. Lorstad.

At least 19 recordsLinked to original sources
arXiv2011

Oscillating HBT radii and the time evolution of the source - sqrt(s_NN) = 200 GeV Au+Au data analyzed with azimuthally sensitive Buda-Lund hydro model

Identified particle spectra of pions, kaons and (anti)protons, and elliptic flow and azimuthal dependence of Bose-Einstein or HBT correlations of identified pions in sqrt(s_NN) = 200 GeV Au+Au collisions is analyzed simultaneously using an ellipsoidally symmetric generalization of the Buda-Lund hydrodynamical model. The transverse flow is found to be faster in the reaction plane than out of plane, which results in a reaction zone that gets slightly more elongated in-plane than out of plane.

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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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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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arXiv2007

From Quark Gluon Plasma to a Perfect Fluid of Quarks and Beyond

With high energy heavy ion collisions one tries to create a new forms of matter that is similar to the one present at the birth of our Universe. Recent development on flow pattern, initial energy-density and freeze-out temperature shows that most likely this new form of matter is in a deconfined state, has colored degrees of freedom and is more fluid-like than gas-like. In present paper we calculate estimations on the physical properties of this new-old matter.

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arXiv2006

Universal scaling of the rapidity dependent elliptic flow and the perfect fluid 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 based on perfect fluid hydrodynamics. We also show that these PHOBOS data satisfy the universal scaling relation predicted by the Buda-Lund hydrodynamical model, based on exact solutions of perfect fluid hydrodynamics.

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arXiv2005

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.

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arXiv2004

Indication of quark deconfinement and evidence for a Hubble flow in 130 and 200 GeV Au+Au collisions

Buda-Lund hydro model fits are compared to BRAHMS, PHENIX, PHOBOS and STAR data on identified particle spectra, two-particle Bose-Einstein or HBT correlations, charged particle pseudorapidity distributions and pseudorapidity as well as p_t dependent elliptic flow in sqrt(s_NN) = 130 and 200 GeV Au+Au collisions at RHIC. Preliminary results indicate that 7/8-th of the particle emitting volume is rather cold, with surface temperature of 105 MeV, but the temperature has a distribution and the most central 1/8-th of the volume is superheated to temperatures above the critical value, T(x) > T_c = 172 \pm 3 MeV.

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arXiv2004

Buda-Lund hydro model for ellipsoidally symmetric fireballs and the elliptic flow at RHIC

The ellipsoidally symmetric extension of Buda-Lund hydrodynamic model is shown here to yield a natural description of the pseudorapidity dependence of the elliptic flow $v_2(η)$, as determined recently by the PHOBOS experiment for Au+Au collisions at $\sqrt{s_{NN}} = 130$ and 200 GeV. With the same set of parameters, the Buda-Lund model describes also the transverse momentum dependence of $v_2$ of identified particles at mid-rapidity. The results confirm the indication for quark deconfinement in Au+Au collisions at RHIC, obtained from a successful Buda-Lund hydro model fit to the single particle spectra and two-particle correlation data, as measured by the BRAHMS, PHOBOS, PHENIX and STAR collaborations.

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arXiv2004

Buda-Lund hydro model and the elliptic flow at RHIC

The ellipsoidally symmetric Buda-Lund hydrodynamic model describes naturally the transverse momentum and the pseudorapidity dependence of the elliptic flow in Au+Au collisions at $\sqrt{s_{NN}} = 130$ and 200 GeV. The result confirms the indication of quark deconfinement in Au+Au collisions at RHIC, obtained from Buda-Lund hydro model fits to combined spectra and HBT radii of BRAHMS, PHOBOS, PHENIX and STAR.

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arXiv2004

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 $σ$ effect.

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arXiv2003

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.

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arXiv2001

Coulomb and core/halo corrections to Bose-Einstein n-particle correlations

We report on a systematic treatment of Coulomb corrections for 3- and n-particle (Bose-Einstein) correlations, leading to a removal of a 100 % systematic error from earlier Coulomb corrections of 5-particle Bose-Einstein correlations in heavy ion collisions. These results are generalized to include strong final state interactions and core-halo effects.

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arXiv1999

Coulomb wave function corrections for n-particle Bose-Einstein correlations

The effect of multi-particle Coulomb final state interactions on higher-order intensity correlations is determined in general, based on a scattering wave function which is solution of the n-body Coulomb Schrödinger equation in (a large part of) the asymptotic region of n-body configuration space. In particular, we study Coulomb effects on the n-particle Bose-Einstein correlation functions of similarly charged particles and remove a systematic error as big as 100% from higher-order multi-particle Bose-Einstein correlation functions.

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arXiv1999

Invariant Buda-Lund Particle Interferometry

The invariant Buda-Lund parameterization of the two-particle Bose-Einstein correlation functions is presented, its derivation is summarized. In its particular multi-variate Gaussian limiting case, the invariant Buda - Lund parameterization is compared to the Bertsch-Pratt and Yano-Koonin-Podgoretskii parameterizations, advantages and shortcomings are discussed. The invariant Buda-Lund parameterizations are given also for non-Gaussian multi-variate distributions, including damped oscillations in the like-particle correlation function, that are similar to the oscillating intensity correlations of binary stars in stellar interferometry. A separation between the pion and the proton source is also estimated in the Buda - Lund hydro framework, the result is utilized to extract the mean proper time of particle emission with the help of fits to E877 data on non-identical particle correlations by Miskowiec.

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arXiv1999

Partial coherence in the core/halo picture of Bose-Einstein n-particle correlations

We study the influence of a possible coherent component in the boson source on the two-, three- and $n$-particle correlation functions in a generalized core/halo type of boson-emitting source. In particular, a simple formula is presented for the strengh of the $n$-particle correlation functions for such systems. Graph rules are obtained to evaluate the correlation functions of arbitrary high order. The importance of experimental determination of the 4-th and 5-th order Bose-Einstein correlation function is emphasized.

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arXiv1998

On source parameters from particle correlations and spectra

Analytic and numeric approximations are studied in detail for a hydrodynamic parameterization of single-particle spectra and two-particle correlation functions in high energy hadron-proton and heavy ion reactions. Two very different sets of model parameters are shown to result in similarly shaped correlation functions and single particle spectra in a rather large region of the momentum space. However, the absolute normalization of the single-particle spectra is found to be highly sensitive to the choice of the model parameters. For data fitting the analytic formulas are re-phrased in terms of parameters of direct physical meaning, like mean transverse flow. The difference between the analytic and numeric approximations are determined as an analytic function of source parameters.

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arXiv1998

Testing Buda-Lund hydro model on particle correlations and spectra in NA44, WA93 and WA98 heavy ion experiments

Analytic and numerical approximations to a hydrodynamical model describing longitudinally expanding, cylindrically symmetric, finite systems are fitted to preliminary NA44 data measured in 200 AGeV central $S + Pb$ reactions. The model describes the measured spectra and HBT radii of pions, kaons and protons, simultaneously. The source is characterized by a central freeze-out temperature of T_0 = 154 +/- 8 +/- 11 MeV, a "surface" temperature of T_r = 107 +/- 28 +/- 18 MeV and by a well-developed transverse flow, = 0.53 +/- 0.17 +/- 0.11. The transverse geometrical radius and the mean freeze-out time are found to be R_G = 5.4 +/- 0.9 +/- 0.7 fm and tau_0 = 5.1 +/- 0.3 +/- 0.3 fm/c, respectively. Fits to preliminary WA93 200 AGeV S + Au and WA98 158 AGeV Pb + Pb data dominated by pions indicate similar model parameters. The absolute normalization of the measured particle spectra together with the experimental determination of both the statistical and the systematic errors were needed to obtain successful fits.

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