163 research outputs found
Relativistic Reduced-Mass and Recoil Corrections to Vacuum Polarization in Muonic Hydrogen, Muonic Deuterium and Muonic Helium Ions
The reduced-mass dependence of relativistic and radiative effects in simple
muonic bound systems is investigated. The spin-dependent nuclear recoil
correction of order (Zalpha)^4 mu^3/m_N^2 is evaluated for muonic hydrogen and
deuterium, and muonic helium ions (mu is the reduced mass and m_N is the
nuclear mass). Relativistic corrections to vacuum polarization of order alpha
(Zalpha)^4 mu are calculated, with a full account of the reduced-mass
dependence. The results shift theoretical predictions. The radiative-recoil
correction to vacuum polarization of order alpha (Z\alpha)^5 ln^2(Zalpha)
mu^2/m_N is obtained in leading logarithmic approximation. The results
emphasize the need for a unified treatment of relativistic corrections to
vacuum polarization in muonic hydrogen, muonic deuterium and muonic helium
ions, where the mass ratio of the orbiting particle to the nuclear mass is
larger than the fine-structure constant.Comment: 6 pages; RevTe
Influence of Shell Parameters on Optical Properties of Spherical Metallic Core-Oxide Shell Nanoparticles
Vacuum polarization in muonic and antiprotonic atoms: the fine structure at medium Z
Effects of vacuum polarization modify the energy levels in atoms with an
orbiting particle heavier than an electron. The dominant effect is due to the
Uehling potential. In this paper we consider the relativistic corrections to
the energy levels caused by the Uehling potential and in particular the fine
structure in muonic and antiprotonic atoms. We derive general expressions and
consider in detail specific regions of parameters which allow simple asymptotic
expansion. We take into account the recoil effects and anomalous magnetic
moment in the case of an antiproton as the orbiting particle
The Lamb shift contribution of very light millicharged particles
The leading order vacuum polarization contribution of very light millicharged
fermions and scalar (spin-0) particles with charge \epsilon e and mass \mu to
the Lamb shift of the hydrogen atom is shown to imply universal, i.e.
\mu-independent, upper bounds on \epsilon: \epsilon \lsim 10^{-4} for \mu \lsim
1 keV in the case of fermions, and for scalars this bound is increased by a
factor of 2. This is in contrast to expectations based on the commonly used
approximation to the Uehling potential relevant only for conventionally large
fermion (and scalar) masses.Comment: 10 pages including 3 figures, version to appear in Physical Review D
(Rapid Communications
Influence of Shell Parameters on Optical Properties of Spherical Metallic Core-Oxide Shell Nanoparticles
Different metal homogeneous nanoparticles have been extensively studied in recent years due to their wide range of potential applications. It is very interesting to investigate core-shell nanoparticles with oxide shell from core metal. The formation of oxide shell on metallic nanoparticles can be achieved by different chemical and physical methods including also natural oxidation of pure metallic nanoparticles in gaseous or liquid media, containing oxygen components (air, water, etc.). We numerically calculated efficiency factors of absorption K abs , scattering K sca , and extinction K ext of radiation with wavelength in the spectral interval 150-1000 nm by spherical homogeneous metallic and two-layered (metal core -oxide metal shell) nanoparticles: Al, Al-Al 2 O 3 and Zn, Zn-ZnO with core radii in the range 5-50 nm and shell thickness 5 nm. Analysis of presented results has been carried out
Relativistic recoil corrections to the electron-vacuum-polarization contribution in light muonic atoms
The relativistic recoil contributions to the Uehling corrections are
revisited. We consider a controversy in recent calculations based on different
approaches including Breit-type and Grotch-type calculations. We have found
that calculations of those authors were in fact done in different gauges and in
some of those gauges contributions the retardation and two-photon-exchange
effects were missed. We have evaluated such effects and obtained a consistent
result from those approaches. We present a correct expression for the
Grotch-type approach which produces a correct gauge-invariant result. We also
consider a finite-nuclear-size correction for the Uehling term. The results are
presented for muonic hydrogen and deuterium atoms and for muonic helium-3 and
helium-4 ions.Comment: Submitted to Phys. Rev. A; in v.2 results for muonic helium are
correcte
Composition of powders produced by electrospark dispersion of metal granules in water
The results of experimental studies of metal powders composition produced by electrospark dispersion according to the scheme "metal electrodes - metal granule loading - distilled water" are given in the paper. With a help of X-ray diffraction analysis and other methods, it was found that chemical and phase composition of dispersion products is determined by affinity of metal to oxygen
Plasmonic and Thermooptical Properties of Spherical Metallic Nanoparticles for Their Thermoplasmonic and Photonic Applications
Investigations and use of nanoparticles (NPs) as photothermal (PT) agents in laser and optical nanotechnology are fast growing areas of research and applications. The potential benefits of NPs applications include possibility for thermal imaging and treatment of materials containing of NPs, applications of NPs for light-to-thermal energy conversion, in catalysis, laser nanomedicine, and chemistry. Efficiency of applications of metallic NPs for laser and optical nanotechnology depends on plasmonic and thermophysical properties of NPs, characteristics of radiation, and surroundingmedium. Herewe present the results of comparative analysis of NP properties (plasmonic, thermooptical, and others) allowing selecting their parameters for thermoplasmonic and photonic applications. Plasmonic and thermooptical properties of several metallic (aurum, silver, platinum, cobalt, zinc, nickel, titanium, cuprum, aluminum, molybdenum, vanadium, and palladium) NPs are theoretically investigated and analysis of them is carried out. Investigation of the influence of NPs parameters (type of metal, radii, optical indexes, density, and heat capacity of NP material), characteristics of radiation (wavelength and pulse duration), and ambient parameters on plasmonic and thermophysical properties of NPs has been carried out. It was established that maximum value of thermooptical parameter (maximum NP temperature) can be achieved with the use of absorption efficiency factor of NP smaller than its maximum valu
Breit Hamiltonian and QED Effects for Spinless Particles
We describe a simplified derivation for the relativistic corrections of order
for a bound system consisting of two spinless particles. We devote
special attention to pionium, the bound system of two oppositely charged pions.
The leading quantum electrodynamic (QED) correction to the energy levels is of
the order of and due to electronic vacuum polarization. We analyze
further corrections due to the self-energy of the pions, and due to recoil
effects, and we give a complete result for the scalar-QED leading logarithmic
corrections which are due to virtual loops involving only the scalar
constituent particles (the pions); these corrections are of order for S states.Comment: 12 pages, LaTeX; references added (J. Phys. B, in press
- …