Application Of Phenomenological Model Research Articles

Prediction of thermomagnetic properties of La0.67Ca0.33MnO3 and La0.67Sr0.33MnO3

The dependence of magnetization on the variation of temperature for La0.67Ca0.33MnO3 and La0.67Sr0.33MnO3 perovskite-type ceramic materials under an external magnetic field was modelled. Application of phenomenological model was performed, showing a good agreement with the experimental data. Temperature dependence of change of both magnetic entropy and specific heat under magnetic field 0.05 T was predicted for La0.67Ca0.33MnO3 and La0.67Sr0.33MnO3. Predicted values of maximum magnetic entropy change, full-width at half-maximum, relative cooling power and maximum specific heat under 0.05 T were evaluated.

Применение феноменологических моделей при прогнозировании процессов разработки нефтяных месторождений

Применение феноменологических моделей при прогнозировании процессов разработки нефтяных месторождений

Absorption in the final state in reactions and decays in the medium

The role of strong absorption of particles in intermediate and final states has been considered. The range of applicability of phenomenological models of absorption has been studied. This model is nonuniversal. Its applicability depends on the type of interaction Hamiltonian and matrix element used. We also demonstrate that the violation of the unitarity condition can produce a qualitative error in the results. The absorption (decay) in the final state does not tend to suppress the total process probability as well as the probability of the channel corresponding to absorption. This is true for the reactions, decays and n¯ conversion in the medium.

General principles of quantum field theory and strong interactions at high energies

The theory of strong interactions did not become solidly based theoretically until an axiomatic approach was formulated. Within the framework of this approach Bogolubov constructed a rigorous foundation for the dispersion-relation method proposed by Gell-Mann, Goldberger, and Thirring. This foundation intensified the study of the analytical properties of amplitudes. Using the axiomatic approach, Lehmann established the analytical properties of the amplitude with respect to the scattering angle. Subsequently, Martin [2], using the condition of unitarity, widened the domain of analyticity. These and subsequent investigations showed that the scattering amplitude is a unified analytical function of dynamic variables. Gradually the flow of research split into two main directions: one with the aim of constructing various models and the other seeking general results based on only a small number of widely accepted axioms. The results reviewed in the present paper mainly refer to the second direction. Therefore, we do not consider in detail the problems connected with the construction and application of phenomenological models. For a long period of time attention was concentrated mostly on the amplitudes of elastic scattering and charge exchange, both because their investigation was relative simple and because the multiparticle production processes did not play an important role at the available accelerator energies. One of the prominent results of that period was Froissart’s derivation of the bound for the behavior of the total cross section. Martin [2] subsequently gave a more general proof for this bound within the framework of an axiomatic method. Considerable attention was also paid to the problem of proving the validity of the Pomeranchuk theorem [5], which states the asymptotic equality of the total cross sections for a particle and an antiparticle interacting with the same target. Increasing total cross sections found at Serpukhov and CERN and confirmed at the FNAL exhibit showed, rather surprisingly, a closeness (in the sense of functional dependence) of the Froissart bound and the experimentally observed behavior. The assumption of functional saturation of the Froissart bound immediately led