Regge Trajectories of Quark Gluon Bags

Using an exactly solvable statistical model, we discuss the equation of state of large/heavy and short-living bags of the quark gluon plasma (QGP).We argue that the large width of the QGP bags explains not only the observed deficit in the number of hadronic resonances, but also clarifies the reason why the heavy QGP bags cannot be directly observed even as metastable states in the hadronic phase. Also the Regge trajectories of large and heavy QGP bags are established both in vacuum and in a strongly interacting medium. It is shown that, at high temperatures, the average mass and width of the QGP bags behave in accordance with the upper bound of the Regge trajectory asymptotics (the linear asymptotics), whereas, for temperatures below Tн=2 (Tн is the Hagedorn temperature), they obey the lower bound of the Regge trajectory asymptotics (the square root one). Thus, for T Tн=2, these bags demonstrate the standard Regge behavior consistent with the string models.Використовуючи точний розв’язок статистичної моделi, обговорено рiвняння стану великих/важких i короткоживучих мiшкiв кварк-глюонної плазми (КГП). Наведено аргументи того, що велика ширина мiшкiв КГП не тiльки пояснює дефiцит кiлькостi адронних резонансiв, але й причину того, що важкi мiшки КГП не можуть безпосередньо спостерiгатися навiть як метастабiльнi стани в адроннiй фазi. Також знайдено Редже траєкторiї великих i важких мiшкiв КГП як у вакуумi, так i в сильновзаємодiючому середовищi. Доведено, що за високих температур середня маса i ширина мiшкiв КГП пiдкорюються верхнiй границi асимптотики траєкторiї Редже (лiнiйна асимптотика), тодi як для температур, нижчих за Tн=2 (Tн – температура Хагедорна), вони пiдкорюються нижнiй границi асимптотики траєкторiй Редже (асимптотика кореня квадратного). Таким чином, для T Tн=2 цi мiшки демонструють стандартну Редже поведiнку, яка узгоджується з моделями струн

Critical Exponents of the Statistical Multifragmentation Model

For the statistical multifragmentation model the critical indices $\alpha^\prime, \beta, \gamma^\prime, \delta$ are calculated as functions of the Fisher parameter $\tau$. It is found that these indices have different values than in Fisher's droplet model. Some peculiarities of the scaling relations are discussed. The basic model predicts for the index $\tau$ a narrow range of values, $1.799< \tau < 1.846$, which is consistent with two experiments on nuclear multifragmentation.Comment: minor changes of the text, four references adde

Transverse activity of kaons and deconfinement phase transition in nucleus–nucleus collisions

AbstractWe found that the experimental results on transverse mass spectrum of kaons produced in central Pb+Pb (Au+Au) collisions show an anomalous dependence on the colliding energy. The inverse slope of the spectrum increases with the energy in the low (AGS) and high (RHIC) energy domains, whereas it remains constant in the intermediate (SPS) energy range. We argue that this anomaly is probably caused by the modification of the equation of state in the transition region between confined and deconfined matter. This observation may be considered as a new signal, in addition to the previously reported anomalies in the pion and strangeness production, of the onset of deconfinement located in the low SPS energy domain

Statistical Multifragmentation in Thermodynamic Limit

An exact analytical solution of the statistical multifragmentation model is found in thermodynamic limit. The model exhibits a 1-st order phase transition of the liquid-gas type. The mixed phase region of the phase diagram, where the gas of nuclear fragments coexists with the infinite liquid condensate, is unambiguously identified. The peculiar thermodynamic properties of the model near the boundary between the mixed phase and the pure gaseous phase are studied. The results for the caloric curve and specific heat are presented and a physical picture of the nuclear liquid-gas phase transition is clarified.Comment: 4 figure

Hadron Spectra and QGP Hadronization in Au+Au Collisions at RHIC

The transverse mass spectra of Omega hyperons and phi mesons measured recently by STAR Collaboration in Au+Au collisions at sqrt(s_NN) = 130 GeV are described within a hydrodynamic model of the quark gluon plasma expansion and hadronization. The flow parameters at the plasma hadronization extracted by fitting these data are used to predict the transverse mass spectra of J/psi and psi' mesons.Comment: 4 pages, 4 figures, Fig. 3 correcte

Omega, J/psi and psi' Transverse Mass Spectra at RHIC

The transverse mass spectra of J/psi and psi' mesons and Omega hyperons produced in central Au+Au collisions at RHIC energies are discussed within a statistical model used successfully for the interpretation of the SPS results. The comparison of the presented model with the future RHIC data should serve as a further crucial test of the hypothesis of statistical production of charmonia at hadronization. Finally, in case of validity, the approach should allow to estimate the mean transverse flow velocity at the quark gluon plasma hadronization.Comment: revised version to appear in Phys. Lett.

Specific heat at constant volume in the thermodynamic model

A thermodynamic model for multifragmentation which is frequently used appears to give very different values for specific heat at constant volume depending upon whether canonical or grand canonical ensemble is used. The cause for this discrepancy is analysed.Comment: Revtex, 7 pages including 4 figure

Model of multifragmentation, Equation of State and phase transition

We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. We draw a p-V diagram for the model and compare with a p-V diagram obtained from a mean-field theory. We investigate the question of chemical instability in the multifragmentation model. Phase transitions in the model are discussed.Comment: Revtex, 9 pages including 6 figures: some change in the text and Fig.

Nuclear and hadron matter equation of state within the induced surface tension approach

We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard core repulsion. The suggested equation of state explicitly contains the surface tension which is induced by particle interaction. At high densities such a surface tension vanishes and in this way it switches the excluded volume treatment of hard core repulsion to its eigen volume treatment. The great advantage of the developed model is that the number of equations to be solved is two and it does not depend on the number of independent hard-core radii. Using the suggested equation of state we obtained a high quality fit of the hadron multiplicities measured at AGS, SPS, RHIC and ALICE energies and studied the properties of the nuclear matter phase diagram. It is shown the developed equation of state is softer than the gas of hard spheres and remains causal up to the several normal nuclear densities. Therefore, it could be applied to the neutron star interior modeling