120050425
KAON ELECTROMAGNETIC RADIUS
We obtain a QCD sum rule for the kaon form factor at small Q2. It determines, with a rather good accuracy, the kaon charge radius which is in agreement with the experimental value. We also discuss a sum rule for the difference .
118213659
Pion form factor in a scalar model
SummaryUsing as an example the simple scalar modelρ(6)3; we describe our method of analysing the bound-state form factors based on the systematic use of the alpha-representation for Feynman diagrams. The nature of «nonrenormalization group» logarithms specific for the form-factor-type problems is investigated. The summation of ladder contributions is performed in the leading-logarithm approximation.RiassuntoUsando come esempio il semplice modello scalareρ(6)3 si descrive il metodo di analizzare i fattori di forma dello stato legato basati sull’uso sistematico della rappresentazione alfa per i diagrammi di Feyman. Si studia la natura dei logaritmi del gruppo di non rinormalizzazione specifico di problemi di tipo fattore di forma. Si esegue la somma dei contributi di a gradini nell’approssimazione del logaritmo principale.РезюмеНа примере простой скалярной моделиρ(6)3 излагается метод анализа формфакторов составных систем, основанный на систематическом использовании альфа-представления фейнмановских диаграмм. Исследуется природа «неренормгрупповых» логарифмов, специфичных для задач формфакторного типа. Проведено суммирование лестничных вкладов в главном лограрифмическом приближении.
125654630
Pion Form-factor and {QCD} Sum Rules
120815334
Local Quark - Hadron Duality and Nucleon Form-factors in {QCD}
Abstract Quark-hadron duality is incorporated to estimate the non-perturbative O(α 0 S -contribution to the nucleon form factors G N E,M ( t ). For 1 t 2 the results are in satisfactory agreement with the existing data. This means that the observed dipole behaviour of G N ( t ) has nothing to do with the short distance dynamics.
125323640
{QCD} Sum Rule Analysis of the Pion Form-factor Behavior in Small $Q^2$ Region
120836438
Quantum gravitational effects in an isotropic universe
Effects of vacuum polarization by an external gravitational field in a system of spinor, scalar, and massive vector particles are considered in the model of conformally flat space-time. Expressions are obtained for the radiative corrections, and the part they play in gravitational theory is analyzed in the limits of weak (Vertical BarR/sup k//sub i/Vertical Bar m/sup 2/) gravitational fields. The Appendix gives expressions for the rate of spontaneous production of real particles by a strong gravitational field and the energy-momentum tensor of real particles in the ultrarelativistic limit; a law of increase of the entropy of an ultrarelativistic medium is also formulated.
204934704
Some recent results in calculating the Casimir energy at zero and finite temperature
The survey summarizes briefly the results obtained recently in the Casimir effect studies considering the following subjects: i) account of the material characteristics of the media and their influence on the vacuum energy (for example, dilute dielectric ball); ii) application of the spectral geometry methods for investigating the vacuum energy of quantized fields with the goal to gain some insight, specifically, in the geometrical origin of the divergences that enter the vacuum energy and to develop the relevant renormalization procedure; iii) universal method for calculating the high temperature dependence of the Casimir energy in terms of heat kernel coefficients.
116304493
Open bosonic string in background electromagnetic field
29836161
Simple method for calculating the Casimir energy for sphere
A simple method for calculating the Casimir energy for a sphere is developed which is based on a direct mode summation and contour integration in a complex plane of eigenfrequencies. The method uses only classical equations determining the eigenfrequencies of the quantum field under consideration. The efficiency of this approach is demonstrated by calculation of the Casimir energy for a perfectly conducting spherical shell and for a massless scalar field obeying the Dirichlet and Neumann boundary conditions on a sphere. The possibility of rationalizing the removal of divergences in this problem as a renormalization of both the energy and the radius of the sphere is discussed.
117621252
Exchange by the hard and soft quanta in the high energy scattering of particles
In the framework of the functional integration method in quantum field theory the method is proposed for constructing scattering amplitude of the particles which interact by means of the exchange of the infinite number of soft quanta and the finite number of hard virtual particles. In this method the form factors of the interacting particles arise in calculations of the scattering amplitude at large angles. It is in agreement with the Wu--Yang conjecture about the elastic form factor role in high energy scattering. (auth)
119410348
Is the Casimir effect relevant to sonoluminescence?
The Casimir energy of a solid ball (or cavity in an infinite medium) is calculated by a direct frequency summation using contour integration. The dispersion is taken into account, and the divergences are removed by making use of the zeta function technique. The Casimir energy of a dielectric ball (or cavity) turns out to be positive and increasing as the radius of the ball decreases. The latter eliminates completely the possibility of explaining, via the Casimir effect, the sonoluminescence for bubbles in a liquid. Besides, the Casimir energy of the air bubbles in water proves to be immensely smaller than the amount of the energy emitted in a sonoluminescent flash. The dispersive effect is shown to be unimportant for the final result.