International Journal of Modern Physics E

Dyson–Schwinger equations furnish a Poincaré covariant framework within which to study hadrons. A particular feature is the existence of a nonperturbative, symmetry preserving truncation that enables the proof of exact results. The gap equation reveals that dynamical chiral symmetry breaking is tied to the long-range behavior of the strong interaction, which is thereby constrained by observables, and the pion is precisely understood, and seen to exist simultaneously as a Goldstone mode and a bound state of strongly dressed quarks. The systematic error associated with the simplest truncation has been quantified, and it underpins a one-parameter model efficacious in describing an extensive body of mesonic phenomena. Incipient applications to baryons have brought successes and encountered challenges familiar from early studies of mesons, and promise a covariant field theory upon which to base an understanding of contemporary large momentum transfer data.

The high energy pn charge exchange and pp elastic scattering reactions are studied in an effective hadron model for the energy range of s ~ 50 to 400 GeV². The main features of the observed differential cross section of the pn charge exchange reaction, the forward peak and the scaling behavior over the large energy range, are well reproduced by a combination of π-, ρ-exchange and a 4-Nucleon contact term. The latter acts as a background field which turns out to be naturally suppressed in elastic N N scattering but contributes significantly to the charge-exchange reaction.

We have tested recent suggestion of anomalous sensitivity in highly excited quantum many-body systems. Two independent measurements of cross sections for the ¹⁹F + ⁹³Nb strongly dissipative heavy-ion collisions have been performed at incident energies from 102 to 108 MeV in steps of 250 keV. In the two measurements we used different, independently prepared, ⁹³Nb target foils with nominally the same thickness. The data indicate statistically significant non-reproducibility of the energy oscillating yields in the two measurements. The observed non-reproducibility is consistent with recent theoretical arguments on spontaneous correlation, slow phase randomization and chaos in highly excited complex quantum systems.

The aim of this paper is to investigate the effect of a non-extensive form of statistical mechanics proposed by Tsallis on the formation of a quark-gluon plasma (QGP). We suggest to account for the effects of the dominant part of the long-range interactions among the constituents in the QGP by a change in the statistics of the system in this phase, and we study the relevance of this statistics for the phase transition. The results show that small deviations (≈ 10%) from Boltzmann–Gibbs statistics in the QGP produce a noticeable change in the phase diagram, which can, in principle, be tested experimentally.

This paper presents evidence of intermittency in target fragmentation in ²⁸Si-AgBr interactions at 14.5 AGeV in emission angle space and azimuthal angle space separately and also in two-dimensional (cos θ,ϕ) space. From the intermittency exponent, the anomalous fractal dimension d_q is calculated and the variation of d_q with the order q is investigated. The authors also compare the results with those obtained from ¹⁶O-AgBr interactions at 60 AGeV and at 2.1 AGeV and ³²S-AgBr interactions at 200 AGeV to study the energy dependence of intermittent type of fluctuations in emission angle and azimuthal angle space separately. Comparing the intermittency exponents in one- and two-dimensions it is further seen that intermittency exponent has a higher value in two-dimensional space.

The total antisymmetric wave functions of the different states of nuclei with A = 5 are calculated by using the basis of the unitary scheme model corresponding to numbers of quanta of excitations N = 1, 2, 3, 4, 5, 6, and 7. The residual interactions used in these calculations are the Gogny et al. potential, the Doma et al. Potential, and an effective interaction which has been used successfully for the nucleus ⁶Li. The energy matrices for nuclei with A = 5 are diagonalized in terms of the oscillator parameter ℏω, which is varied in order to obtain the best fit to the spectra of these nuclei. The binding energy, the root mean-square radius, and the magnetic dipole moment of ⁵He are also calculated. Some new levels for these nuclei are obtained. The role of the three-body forces is also investigated for the nucleus ⁵He.

The cross-sections of the muonic atom interactions in the muon catalyzed fusion (μCF) cycle are spin dependent. In this paper we answer an interesting question about the efficiency of μCF: "Dose the efficiency of μCF increase by spin polarization of the injected beam of muons in the spin polarized D/T mixture?" To answer this question we investigate the spin polarization effects on the kinetics of the μCF cycle by simulating the collisional processes of the μt atoms by the Monte–Carlo method. The themalization and spin-flip rates are determined and used to simulate the kinetics of μCF in the spin polarized condition. Then, the total number of fusions per muon in two cases, spin polarized and unpolarized conditions, are compared. We have shown the spin polarization condition is rapidly converted to the unpolarized case in μCF cycle and its effects can be ignored, especially if the concentration of tritium increases.