Jean Letessier

Evidence for a phase with high specific entropy in nuclear collisions

We determine the entropy per baryon content of the central reaction region in terms of the charged particle multiplicity. We study the consistency of our findings with recent data on strange anti-baryon production at 200 GeV A in S→A collisions (A∼200) assuming formation of a central fireball. Hadron gas models which do not invoke strong medium modifications of hadron masses do not provide enough entropy and are inconsistent with the combined experimental results. In contrast the quark-gluon plasma hypothesis explains them naturally. PACS 25.75.+r, 12.38.Mh Published in Phys. Rev. Letters 70 (1993) 3530–3533. PAR/LPTHE/92–37 TPR-92-39 AZPH-TH/92-30 September 30, 1992 Work supported by DFG, BMFT, GSI, and NATO, grant CRG 910991 Work supported by DOE, grant DE-FG02-92ER 40733, and NATO, grant CRG 910991 Unité associée au CNRS

Linear birth and death models and associated Laguerre and Meixner polynomials

Abstract We study birth and death processes with linear rates λ n = n + α + c + 1, μ n + 1 = n + c , n ⩾ 0 and μ 0 is either zero or c . The spectral measures of both processes are found using generating functions and the integral transforms of Laplace and Stieltjes. The corresponding orthogonal polynomials generalize Laguerre polynomials and the choice μ 0 = c generates the associated Laguerre polynomials of Askey and Wimp. We investigate the orthogonal polynomials in both cases and give alternate proofs of some of the results of Askey and Wimp on the associated Laguerre polynomials. We also identify the spectra of the associated Charlier and Meixner polynomials as zeros of certain transcendental equations.

Hadron production and quark-gluon plasma hadronization in Pb-Pb collisions at

We show that all central rapidity hadron yields measured in Pb--Pb collisions at

\sqrt{s_{NN}}=2.76

\sqrt{s_{NN}}=2.76

TeV

TeV are well described by the chemical non-equilibrium statistical hadronization model (SHM), where the chemically equilibrated QGP source breaks up directly into hadrons. SHM parameters are obtained as a function of centrality of colliding ions, and we compare CERN Large Hadron Collider (LHC) with Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) results. We predict yields of unobserved hadrons and address anti-matter production. The physical properties of the quark--gluon plasma fireball particle source show universality of hadronization conditions at LHC and RHIC.

Strangeness conservation in hot nuclear fireballs.

Within a thermal model generalized to allow for nonequilibrium strange particle abundances we study how the constraint that the balance of strangeness in a fireball is (nearly) zero impacts the allowable thermal fireball parameters. Using the latest data of the CERN-WA85 experiment for the case of 200[ital A] GeV S-[ital A] ([ital A][similar to]200) collisions we extract the values of the thermal parameters considering in detail the impact of hadronic resonance decays on the abundances and spectral form of strange baryons and antibaryons. Given these results and invoking further the observed charged particle multiplicities we are able to consider the (specific) entropy content of the fireball in order to understand the nature of the disagreement of the hadronic gas picture of the fireball with the experimental data.

Sudden Hadronization in Relativistic Nuclear Collisions

We formulate and study a mechanical instability criterion for sudden hadronization of dense matter fireballs formed in 158A GeV Pb-Pb collisions. Considering properties of quark-gluon matter and hadron gas we obtain the phase boundary between these two phases and demonstrate that the required deep quark-gluon-plasma supercooling prior to sudden hadronization has occurred.

SHAREv2 : fluctuations and a comprehensive treatment of decay feed-down

This the user’s manual for SHARE version 2. SHARE [G. Torrieri, S. Steinke, W. Broniowski, W. Florkowski, J. Letessier, J. Rafelski, Comput. Phys. Comm. 167 (2005) 229] (Statistical Hadronization with Resonances) is a collection of programs designed for the statistical analysis of particle production in relativistic heavy-ion collisions. While the structure of the program remains similar to v1.x, v2 provides several new features such as evaluation of statistical fluctuations of particle yields, and a greater versatility, in particular regarding decay feed-down and input/output structure. This article describes all the new features, with emphasis on statistical fluctuations. Program summary

QCD equations of state and the quark-gluon plasma liquid model

Recent advances in the study of equations of state of thermal lattice Quantum Chromodynamics obtained at non-zero baryon density allow validation of the quark-gluon plasma (QGP) liquid model equations of state (EoS). We study here the properties of the QGP-EoS near to the phase transformation boundary at finite baryon density and show a close agreement with the lattice results.

Gluon production, cooling, and entropy in nuclear collisions

We study the cooling (heating) of a glue-parton gas due to production (destruction) of particles and determine the associated evolution of entropy. We incorporate sharing of the system energy among a changing number of particles. We find that the entropy of an evolving glue-parton gas hardly changes, once the initial thermalized state has been formed, despite a significant change in particle number and temperature.