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.
120508035
Covariant formalism for a relativistic string in a constant homogeneous electromagnetic field
16432431
Functionals linear in curvature and protein folding
The free energy of globular protein chain is considered to be a functional defined on smooth curves in three dimensional Euclidean space. From the requirement of geometrical invariance, together with basic facts on conformation of helical proteins and dynamical characteristics of the protein chains, we are able to determine, in a unique way, the exact form of the free energy functional. Namely, the free energy density should be a linear function of the curvature of curves E-mail: feoli@unisannio.it; fax: +39089965275 E-mail: nestr@thsun1.jinr.ru E-mail: scarpetta@sa.infn.it
121905919
Eikonal approximation for high-energy inclusive processes
17711121
Boundary conditions at spatial infinity for fields in Casimir calculations
The importance of imposing proper boundary conditions for fields at spatial infinity in the Casimir calculations is elucidated.
118320834
Surface modes and photonic modes in Casimir calculations for a compact cylinder
A rigorous formulation of the problem of calculating the electromagnetic vacuum energy of an infinite dielectric cylinder is discussed. It is shown that the physically relevant spectrum of electromagnetic excitations includes the surface modes and photonic modes. The mathematical procedure of summing over this spectrum is proposed, and the transition to imaginary frequencies is accomplished. As a result, the imaginary-frequency representation for the vacuum energy is justified which has been used in previous Casimir studies for this configuration.
125323640
{QCD} Sum Rule Analysis of the Pion Form-factor Behavior in Small $Q^2$ Region
116346471
APPLICATION OF NUCLEAR THEORY METHODS TO NEW FAMILY OF FERMI SYSTEM
Duo to a remarkable progress in experimental techniques, the new family of .small Fermi systems (SFS) (metal clusters, fullerencs, helium clusters and quantum dots) was discovered about ten years ago. As was established, those Fermi systems have a striking similarity with atomic nuclei (see re­views and conference proceedings [1-9]). The most remarkable feature of now SFS is that they possess a mean field of the same kind as in atomic iniclci which allows one to investigate SFS by nuclear theory methods. If recent investigations of SFS have mainly been limited to atoms and atomic nuclei, our present possibilities have become much wider, We have really obtained a good chance for studying both a common behavior of SFS and a wonderful variety of their properties. In the present paper, the particular properties of the new SFS as well as the application of nuclear physics methods to their description are briefly reviewed. The properties of the new SFS and atomic nuclei are continually compared. The main attention is paid to metal clusters (MC) or, more precisely, to E\ giant resonances (GR) in this system. Iri Sec.2, the sketch of basic properties of MC as well as the perspectives of their investigation arc given. Sec.3 is devoted to the description of E\ GR in MC, In Sec.3 the properties of fullerencs, helium clusters and quantum dots are outlined. In Sec.4 the conclusions are presented.
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.
121516467
CollectiveEλ excitations of surface character in spherical and deformed sodium clusters: vibrating potential model
The self-consistent vibrating potential model (VPM) is extended for the description ofEλ surface collective excitations in alkali metal clusters with practically any kind of static deformation. The case of spherical clusters is also covered. Any single-particle potentials and valence electron densities for which the coefficients of the multipole expansion are known can be used within the model. The strength function method incorporated into the model allows one to avoid solving the equations for every state and, as a result, simplifies the calculations drastically. The model is of a quite general character and can also be used for description of giant resonances in atomic nuclei if the Coulomb terms are neglected. The VPM is applied to calculate theE1,E2 andE3 excitations in spherical (Na8, Na20 and Na40) and deformed (Na10, Na18 and Na26) clusters.
123206973
The interior of the charge transition density and the structure of low-lying states in deformed nuclei
The RPA calculations of charge transition densities (CTD) rho lambda mu nu (r) for the E2 transitions from the ground state to the low-lying Ipi Knu =2+2nu and 2+0nu states in 164Dy predict rather strong peaks of single-particle nature in the interior of the CTD. A simple explanation of the results is given. The reliability of the results obtained, their possible application to the study of the structure of low-lying states and some predictions for nuclei of the rare-earth region are discussed.