220,637 research outputs found
What are the left-handed media and what is interesting about them?
We review the intensively discussed ideas about wave propagation and
refraction in media where both electric permittivity and magnetic permeability
are negative. The criticism against negative refraction as violating the
causality principle is considered. Starting from the initial wave equations,
refraction of beams at the boundary of a left-handed medium is analyzed. The
physics of a perfect lens formed by a flat layer of a left-handed material is
considered.Comment: 21 pages, 8 figure
Few-Nucleon Systems: Notes about the Status and Results of Investigations
Radiation technologies have found wide application in power engineering,
medicine, biology and other areas of human activities. However, theoretical
calculations of nuclear reactions and, correspondingly, the interpretation of
experimental results appear model-dependent. The model-independent calculation
of the nuclear reaction must take into account the structure of the nuclear
ground state, the final-state nucleon interaction and the contribution of meson
exchange currents. These calculations can be carried out only with due regard
for realistic NN and 3N forces between nucleons and also, with the use of exact
methods of solving the many-body problem. In this technique it is expedient to
conduct investigations of nuclear reactions as from few-nucleon systems in the
energy area of the particles below the meson-producing threshold. The tensor
part of NN interaction and 3NF,s generate the lightest nuclei states with
nonzero orbital momenta of nucleons. These states in the lightest nuclei is
conditioned the properties of inter-nucleonic forces, and therefore, similar
effects should be observed unexceptionally in all nuclei. The review papers are
generally devoted to three-nucleon systems. In this paper primary attention is
given to the investigation of the He nucleus
Dirac equation in the confining SU(3)-Yang-Mills field and relativistic effects in charmonium spectrum
The recently obtained solutions of the Dirac equation in the confining
SU(3)-Yang-Mills field in Minkowski spacetime are applied to describe the
energy spectrum of charmonium. The nonrelativistic limit is considered for the
relativistic effects to be estimated in a self-consistent way and it is shown
that the given effects could be extremely important for both the energy
spectrum and the confinement mechanism.Comment: 9 pages,LaTe
Parametrization of U(N)-monopoles on black holes by the moduli space of holomorphic vector bundles over two-sphere and black hole entropy
We discuss how to describe U(N)-monopoles on the Schwarzschild and
Reissner-Nordstr\"om black holes by the parameters of the moduli space of
holomorphic vector bundles over S^2. For N = 2,3 we obtain such a description
in an explicit form as well as the expressions for the corresponding monopole
masses. This gives a possibility to adduce some reasonings in favour of
existence of both a 'fine structure' for black holes and the statistical
ensemble tied with it which might generate the black hole entropy. Also there
arises some analogy with the famous K-theory in topology.Comment: 19 pages, LaTeX, minor modifications for correspondence to the
published versio
- …