119446437
Spectral analysis of a flat plasma sheet model
The spectral analysis of the electromagnetic field on the background of an infinitely thin flat plasma layer is carried out. This model loosely imitates a single base plane from graphite and it is of interest for theoretical studies of fullerenes. By making use of the Hertz potentials the solutions to Maxwell equations with the appropriate matching conditions at the plasma layer are derived and on this basis the spectrum of electromagnetic oscillations is determined. The model is naturally split into the TE-sector and TM-sector. Both the sectors have positive continuous spectra, but the TM-modes have in addition a bound state, namely, the surface plasmon. This analysis relies on the consideration of the scattering problem in the TE- and TM-sectors. The spectral zeta-function and integrated heat kernel are constructed for different branches of the spectrum in an explicit form. As a preliminary, the rigorous procedure of integration over the continuous spectra is formulated by introducing the spectral density in terms of the scattering phase shifts. The asymptotic expansion of the integrated heat kernel at small values of the evolution parameter is derived. By making use of the technique of integral equations, developed earlier by the same authors, the local heat kernel (Green's function or fundamental solution) is also constructed. As a by-product, a new method is demonstrated for deriving the fundamental solution to the heat conduction equation (or to the Schrodinger equation) on an infinite line with the δ-like source. In particular, for the heat conduction equation on an infinite line with the δ-source a nontrivial counterpart is found, namely, a spectral problem with point interaction, which possesses the same integrated heat kernel while the local heat kernels (fundamental solutions) in these spectral problems are different.
126085042
ON THE INTERPRETATION OF THE NOETHER IDENTITIES
121905919
Eikonal approximation for high-energy inclusive processes
15884859
Casimir energy of a nonuniform string
The Casimir energy of a non-uniform string built up from two pieces with different speed of sound is calculated. A standard procedure of subtracting the energy of an infinite uniform string is applied, the subtraction being interpreted as the renormalization of the string tension. It is shown that in the case of a homogeneous string this method is completely equivalent to the zeta renormalization.
29489956
Direct mode summation for the Casimir energy of a solid ball
The Casimir energy of a solid ball placed in an infinite medium is calculated by a direct frequency summation using the contour integration. It is assumed that the permittivity and permeability of the ball and medium satisfy the condition . After deriving the general expression for the Casimir energy, a compact ball is considered when . Calculations are carried out which are of the first order in and take account of the fifth-order terms in the uniform asymptotic expansion of the Bessel functions involved. The implication of the results to attempt to explain sonoluminescence via the Casimir effect is briefly discussed.
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.
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.
117583655
Overlap of metal clusters and nuclear structure physics
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.
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.
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.