International Journal of Modern Physics E

Thermodynamical properties of nuclear matter are studied in the framework of an effective many-body field theory at finite temperature, considering the Sommerfeld approximation. We perform the calculations by using the nonlinear Boguta and Bodmer model, extended by the inclusion of the fundamental baryon octet and leptonic degrees of freedom. Trapped neutrinos are also included in order to describe protoneutron star properties through the integration of the Tolman–Oppenheimer–Volkoff equations, from which we obtain, beyond the standard relations for the masses and radii of protoneutron stars as functions of the central density, new results of these quantities as functions of temperature. Our predictions include: the determination of an absolute value for the limiting mass of protoneutron stars; new structural aspects on the nuclear matter phase transition via the behavior of the specific heat and, through the inclusion of quark degrees of freedom, the properties of a hadron-quark phase transition and hybrid protoneutron stars

The correlations between the multiplicities of secondary charged particles emitted in collisions of 3 A GeV/c⁷Li with emulsion have been studied. The dependence of the correlation strength on the mass number of the projectile has been analyzed. Moreover, the dependence of the average multiplicities of shower particle emitted in the forward and backward hemispheres on the number of target fragments has been investigated. The study of the number of backward slow protons (black and grey particles) indicates that, while the number of backward particles is a good factor representing the purely target fragments, the number of backward grey particles can be considered an accurate experimental factor for the impact parameter dependence of the collision.

In a previous paper, we derived a master equation for fermions, of Lindblad's form, with coefficients depending on microscopic quantities. In this paper, we study the properties of the dissipative coefficients taking into account the explicit expressions of: (a) the matrix elements of the dissipative potential, evaluated from the condition that, essentially, this potential induces transitions among the system eigenstates without significantly modifying these states, (b) the densities of the environment states according to the Thomas–Fermi model, and (c) the occupation probabilities of these states taken as a Fermi–Dirac distribution. The matrix of these coefficients correctly describes the system dynamics: (a) for a normal, Fermi–Dirac distribution of the environment population, the decays dominate the excitation processes; (b) for an inverted (exotic) distribution of this population, specific to a clustering state, the excitation processes are dominant.

The occurrence of intermittent patterns in 14.5A GeV/c²⁸Si-nucleus interactions is examined in terms of Scaled Factorial Moments (SFMs), introduced by Bialas and Peschanski. Further, to examine the dependence of various interesting characteristics of SFMs on incident energy, the data on 4.5A GeV/c²⁸Si-nucleus collisions available in our laboratory are analyzed. Interestingly, log-log plots between rapidity interval δη and the qth order factorial moment F_q for both the energies exhibit linear behavior indicating thereby the presence of intermittency in the interactions investigated. Moreover, to look at the fractal nature of the particle emitting sources, variation of the fractal dimensions, d_q with the order of the moment is investigated. Finally, study of the variation of λ_q [=(ϕ_q+1)/q)] with the order of the moment, q indicates a possibility of non-thermal phase transition in certain types of events

In the present work we use the finite range density dependent effective Gogny interaction to study the equation of state of polarized nuclear matter. Six sets of the interaction parameters are used and a comparison is made with the calculations of Friedman and Pandharipande using a realistic interaction. One of the parameter sets (D1) gives similar results for the properties of polarized nuclear matter while the other parameter sets (D1S, D250, D260, D280 and D300) yield results which are reasonably comparable with the realistic interaction calculation of Friedman and Pandharipande

A realization of the ladder operators for the solutions to the Schrödinger equation with a pseudoharmonic oscillator in 2D is presented. It is shown that those operators satisfy the commutation relations of an SU(1, 1) algebra. Closed analytical expressions are evaluated for the matrix elements of some operators r² and r∂/∂ r

The characteristics of the interactions of 4.5A GeV/c²⁸Si nuclei with emulsion have been investigated. The method of separating interactions into those with hydrogen, light and heavy target nuclei has been discussed. The multiplicity distribution, average multiplicities, multiplicity correlation and the angular distributions of the secondary particles emitted in ²⁸Si-emulsion are calculated according to the Modified Fritiof Model and compared with the experimental data and with other available data for p, ¹²C, ²⁴Mg at the same energy. It has been found that the modified Fritiof model can describe the multiplicity characteristics of the different emitted particles in the above-mentioned interaction with different target groups. The comparison of the experimental data with the modified Fritiof model shows no clear preference for the case of the light target while it seems to be nearer to the experimental data in the case of the heavy target and the emulsion