A scalar field theory with a variable cosmological term

From the standpoint of cosmology, we investigate the relationship between the Brans-Dicke scalar field ø and the scalar field in particle physics (hereafter abbreviated as p.p.) on the assumption that ø is an arbitrary function ofr, but not oft. And also we see whether the cosmological term A which was originally introduced into cosmology without a relationship to p.p. can be related to the symmetry-breaking term in p.p., supposing a dependence of A upon ø.     

On the variation of the effective cosmological term

In the framework of classical field theory, we try to explain why the effective cosmological constant is so small. The basis of the attempt is a Higgs field that shall determine the global structure of the universe. Einstein's theory of gravitation does not allow one to realize the idea. But we are successful if we start from some variant of the scalar-tensor theory of gravitation, choosing for the parameters that enter the Lagrangean of the Higgs field the Compton length of a proton and Eddington's number as self-coupling constant.     

The cosmological term and a modified Brans-Dicke cosmology

Adding the cosmological term , which is assumed to be variable in this paper, to the Brans-Dicke Lagrangian, we try to understand the meaning of the term and to relate it to the mass of the universe. We also touch upon the Dirac large-number hypothesis, applying the results obtained from the application of our theory to a uniform cosmological model.     

A mechanism for obtaining a rapidly decreasing cosmological term at classical scales

Generalized symmetries of the gravitational field equations are used to demonstrate that the average value of the cosmological term decreases rapidly to zero after the inflationary epoch.     

An effective action for a variable electromagnetic field

This work consists essentially of two parts. The first part is an analysis of the one-loop effective action using the zeta-function approach. This gives a simple expression for the effective action in terms of the background field propagator. The next-of-kin to the zeta-function, the heat kernel, is given in terms of B. DeWitt's proper time expansion (also known as P. B. Gilkey's theorem). It is calculated in the second part for fermions interacting with an external electromagnetic field to first nonvanishing order in the variations of the gauge field.     

Expanding models with a varying cosmological term and bulk stress

The effect of a varying cosmological term and a dissipative bulk stress on the evolution of a homogeneous and isotropic universe is investigated. In the cases of interest neither analytical nor qualitative analysis is feasible and so we study these numerically only. Our work extends that of Calvão et al. to bulk stresses not considered in their analysis.     

Application of an inverse-scattering method to determine the effective interaction between composite particles

An inverse-scattering method developed recently by Münchow and Scheid is used to determine the effective potential between two α-particles. The α-α scattering phase shifts from a microscopic calculation using the generator coordinate method are employed with the inversescattering technique to obtain a unique, energy-dependent optical potential. A comparison of this potential with the direct (or folded) potential clearly reveals the Pauli exchange effects arising from the inclusion of nuclear exchange between the two a-particles. It is shown that the inverse-scattering approach is accurate for the α-α system even at low energies and should be applicable to heavy-ion systems.     

Quintessential inflation from a variable cosmological constant in a 5D vacuum

We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experimental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe.     

Basic properties of the Einstein equations with a Ricci-Scalar-Dependent cosmological term

Basic properties of the Einstein equations modified by a cosmological Λ-term dependent on the Ricci scalar R are considered. We show that in addition to a nonzero divergence of the energy-momentum tensor of the matter and the consequent cold matter mass nonconservation as the Universe expands, this model suggests a significant modification of the equations for the gravitational potential and particle acceleration in the Newtonian approximation. These circumstances allow the necessary criteria for possible functional dependences Λ(R) to be formulated. Nevertheless, by introducing a variable Λ-term, we can look at the problems of dark matter and dark energy anew. In particular, we show that the model in which the cosmological term depends linearly on the Ricci scalar (this corresponds to the approximation of a more complex dependence in the case of low matter densities) makes it possible to satisfactorily describe the rotation curves of galaxies without invoking the dark matter hypothesis and to construct a cosmological model with a variable vacuum energy density, in qualitative agreement with the present views of the early Universe.     

How to determine cost savings for a records/files management program.

This article provides some guidelines for distinguishing between feelings and facts in order to determine the cost savings potential for a particular system, first to convince oneself of the "rightness" of the new approach and second, to convince other decision makers in the organization of the true benefits, including economic benefits of the change.     

The CWKB approach to non-reflecting potential and cosmological implications

We discuss the method of calculating the reflection coefficient using complex trajectory WKB (CWKB) approximation to understand the non-reflecting nature of the potentialU(x) = -U ₀/cosh²(x/a). We show that the repeated reflections between the turning points whose paths are in conformity with Bogolubov transformation technique are essential in obtaining the non-reflecting condition. We also discuss the implications of the results when applied to the particle production scenario. We use the CWKB technique developed by one of the authors (SB) to obtain the results which agree very well with those obtained by exact quantum mechanical calculations.     

The effective interface potential for a superconducting layer

The effective interface potential is derived for a superconducting layer attached to a wall. The expression applies to the neighborhood of a continuous wetting or delocalization transition, which exists for type I superconductors with a negative extrapolation length. From this potential a number of features can be easily derived, such as the locus of the phase transition and the critical exponents. Whereas the order parameter exponent is universal, other exponents, like the susceptibility exponent, are not.     

Evidence for a symmetry term in the optical potential for neutrons

The analyses of 6, 7 and 8 MeV neutron differential elastic scattering of 13 elements ranging from Al to Bi have revealed evidence for a symmetry term in the real optical neutron potential. It is also shown that the real-potential depth is a decreasing function of the mass number at each energy.     

Pseudospin symmetry for modified Rosen-Morse potential including a Pekeris-type approximation to the pseudo-centrifugal term

By a novel algebraic method we study the approximate solution to the Dirac equation with scalar and vector second P?schl-Teller potential carrying spin symmetry. The transcendental energy equation and spinor wave functions with arbitrary spin-orbit coupling quantum number k are presented. It is found that there exist only positive-energy bound states in the case of spin symmetry. Also, the energy eigenvalue approaches a constant when the potential parameter a \alpha goes to zero. The equally scalar and vector case is studied briefly.