Browsing by Author "Abo Elyazeed, Eman R."

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Chemical freezeout parameters within generic nonextensive statistics
(INDIAN ASSOC CULTIVATION SCIENCE, INDIAN J PHYSICS, JADAVPUR, KOLKATA 700 032, INDIA, 2018-10) Tawfik, Abdel; Yassin, Hayam; Abo Elyazeed, Eman R.
The particle production in relativistic heavy-ion collisions seems to be created in a dynamically disordered system which can be best described by an extended exponential entropy. In distinguishing between the applicability of this and Boltzmann-Gibbs (BG) in generating various particle-ratios, generic (non)extensive statistics is introduced to the hadron resonance gas model. Accordingly, the degree of (non)extensivity is determined by the possible modifications in the phase space. Both BG extensivity and Tsallis nonextensivity are included as very special cases defined by specific values of the equivalence classes (c,d). We found that the particle ratios at energies ranging between 3.8 and 2760GeV are best reproduced by nonextensive statistics, where c and d range between 0.9. The present work aims at illustrating that the proposed approach is well capable to manifest the statistical nature of the system on interest. We don't aim at highlighting deeper physical insights. In other words, while the resulting nonextensivity is neither BG nor Tsallis, the freezeout parameters are found very compatible with BG and accordingly with the well-known freezeout phase-diagram, which is in an excellent agreement with recent lattice calculations. We conclude that the particle production is nonextensive but should not necessarily be accompanied by a radical change in the intensive or extensive thermodynamic quantities, such as internal energy and temperature. Only, the two critical exponents defining the equivalence classes (c,d) are the physical parameters characterizing the (non)extensivity.
On thermodynamic self-consistency of generic axiomatic-nonextensive statistics
(IOP PUBLISHING LTD, 2017-05) Abo Elyazeed, Eman R.; Yassin, Hayam; Tawfik, Abdel Nasser
Generic axiomatic-nonextensive statistics introduces two asymptotic properties, to each of which a scaling function is assigned. The first and second scaling properties are characterized by the exponents c and d, respectively. In the thermodynamic limit, a grand -canonical ensemble can be formulated. The thermodynamic properties of a relativistic ideal gas of hadron resonances are studied, analytically. It is found that this generic statistics satisfies the requirements of the equilibrium thermodynamics. Essential aspects of the thermodynamic self-consistency are clarified. Analytical expressions are proposed for the statistical fits of various transverse momentum distributions measured in most-central collisions at different collision energies and colliding systems. Estimations for the freezeout temperature (T-ch) and the baryon chemical potential (mu(b)) and the exponents c and d are determined. The earlier are found compatible with the parameters deduced from Boltzmann-Gibbs (BG) statistics (extensive), while the latter refer to generic nonextensivities. The resulting equivalence class (c, d) is associated with stretched exponentials, where Lambert function reaches its asymptotic stability. In some measurements, the resulting nonextensive entropy is linearly composed on extensive entropies. Apart from power-scaling, the particle ratios and yields are excellent quantities to highlighting whether the particle production takes place (non)extensively. Various particle ratios and yields measured by the STAR experiment in central collisions at 200, 62.4 and 7.7 GeV are fitted with this novel approach. We found that both c and d < 1, i.e. referring to neither BG-nor Tsallis-type statistics, but to (c, d) entropy, where Lambert functions exponentially rise. The freezeout temperature and baryon chemical potential are found comparable with the ones deduced from BG statistics (extensive). We conclude that the particle production at STAR energies is likely a nonextensive process but not necessarily BG or Tsallis type.
Strangeness chemical potential from the baryons relative to the kaons particle ratios
(WORLD SCIENTIFIC PUBL CO PTE LTD, 2017) Tawfik, Abdel Nasser; Abdel Wahab, Magda; Yassin, Hayam; Abo Elyazeed, Eman R.; El Din, Hadeer M. Nasr
From a systematic analysis of the energy-dependence of four antibaryon-to-baryon ratios relative to the antikaon-to-kaon ratio, we propose an alternative approach determining the strange-quark chemical potential (mu(s)). It is found that mu(s) generically genuinely equals one-fifth the baryon chemical potential (mu(b)). An additional quantity depending on mu(b) and the freezeout temperature (T) should be added in order to assure averaged strangeness conversation. This quantity gives a genuine estimation for the possible strangeness enhancement with the increase in the collision energy. At the chemical freezeout conditioned to constant entropy density normalized to temperature cubed, various particle ratios calculated at T and mu(b) and the resultant mu(s) excellently agree with the statistical-thermal calculations.