Browsing by Author "Yassin, Hayam"

Now showing 1 - 6 of 6

Chemical freeze-out in Hawking-Unruh radiation and quark-hadron transition
(AMER PHYSICAL SOC, 2015) Tawfik, Abdel Nasser; Yassin, Hayam; Elyazeed, Eman R. Abo
The proposed analogy between hadron production in high-energy collisions and Hawking-Unruh radiation process in the black holes shall be extended. This mechanism provides a theoretical basis for the freeze-out parameters, the temperature (T), and the baryon chemical potential (mu), characterizing the final state of particle production. The results from charged black holes, in which the electric charge is related to mu, are found comparable with the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in thermal statistical models and Polyakov linear-sigma model. Furthermore, the resulting freeze-out condition < E > / < N > similar or equal to 1 GeV for average energy per particle is in good agreement with the hadronization process in the high-energy experiments. For the entropy density (s), the freeze-out condition s/T-3 similar or equal to 7 is found at mu less than or similar to 0.3 GeV. Then, due to the dependence of T on mu, the values of s/T-3 increase with increasing mu. In accordance with this observation, we found that the entropy density (s) remains constant with increasing mu. Thus, we conclude that almost no information is going lost through Hawking-Unruh radiation from charged black holes. It is worthwhile to highlight that the freeze-out temperature from charged black holes is determined independent on both freeze-out conditions.
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.
Phenomenology of light- and strange-quark simultaneous production at high energies
(PLEIADES PUBLISHING INC, 2017-11) Elyazeed, Eman R. Abo; Yassin, Hayam; Tawfik, Abdel Nasser
This letter presents an extension of EPL116(2017) 62001 to light- and strange-quark nonequilibrium chemical phase-space occupancy factors (gamma(q,s)). The resulting damped trigonometric functionalities relating gamma(q,s) to the nucleon-nucleon center-of-mass energies (root s(NN)) looks very similar except different coefficients. The phenomenology of the resulting gamma(q,s) (root s(NN)) describes a rapid decrease at root s(NN) less than or similar to 7 GeV followed by a faster increase up to similar to 20 GeV. Then, both gamma(q,s) become nonsensitive to root s(NN). Although these differ from gamma(s) (root s(NN)) obtained at gamma(q) (root s(NN)) = 1, various particle ratios including K+/pi(+), K-/pi(-), Lambda/pi(-), (Lambda) over bar/pi(-), Xi(+)/pi(+), and Omega/pi(-), can well be reproduced, as well. We conclude that gamma(q,s) (root s(NN)) should be instead determined from fits of various particle yields and ratios but not merely from fits to the particle ratio k(+)/pi(+).
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.
Strangeness production in high-energy collisions and Hawking-Unruh radiation
(WORLD SCIENTIFIC PUBL. CO. PTE LTD, 2017) Tawfik, Abdel Nasser; Yassin, Hayam; Elyazeed, Eman R. Abo
The assumption that the production of quark-antiquark pairs and their sequential string-breaking takes place, likely as a tunneling process, through the event horizon of the color confinement determines the freezeout temperature and gives a plausible interpretation for the thermal pattern of elementary and nucleus-nucleus collisions. When relating the black-hole electric charges to the baryon-chemical potentials, it was found that the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in the statistical thermal models and Polyakov linear-sigma model agree well with the ones determined from the thermal radiation from charged black hole. Accordingly, the resulting freezeout conditions, such as normalized entropy density s/T-3 = 7 and average energy per particle < E > / < N > similar or equal to 1 GeV, are confirmed at finite chemical potentials as well. Furthermore, the problem of strangeness production in elementary collisions can be interpreted by thermal particle production from the Hawking-Unruh radiation. Consequently, the freezeout temperature depends on the quark masses. This leads to a deviation from full equilibrium and thus a suppression of the strangeness production in the elementary collisions. But in nucleus-nucleus collisions, an average temperature should be introduced in order to dilute the quark masses. This nearly removes the strangeness suppression. An extension to finite chemical potentials is introduced. The particle ratios of kaon-to-pion (K+/pi(+)), phi-to-kaon (phi/K-) and antilambda-to-pion ((Lambda) over bar/pi(-)) are determined from Hawking-Unruh radiation and compared with the thermal calculations and the measurements in different experiments. We conclude that these particle ratios can be reproduced, at least qualitatively, as Hawking-Unruh radiation at finite chemical potential. With increasing energy, both K+/pi(+) and phi/K- keep their maximum values at low SPS energies. But the further energy decrease rapidly reduces both ratios. For (Lambda) over bar / pi(-), there is an increase with increasing root sNN, i.e., no saturation is to be observed.