1,009 research outputs found
Supersymmetry in Quantum Mechanics of Colored Particles
The role of supercharge operators is studied in the case of a Dirac particle
moving in a constant chromomagnetic field. The Hamiltonian is factorised and
the ground state wave function in the case of unbroken supersymmetry is
determined.Comment: 8 pages, no figure
AdS/CFT correspondence via R-current correlation functions revisited
Motivated by realizing open/closed string duality in the work by Gopakumar
[Phys. Rev. D70:025009,2004], we study two and three-point correlation
functions of R-current vector fields in N=4 super Yang-Mills theory. These
correlation functions in free field limit can be derived from the worldline
formalism and written as heat kernel integrals in the position space. We show
that reparametrizing these integrals converts them to the expected AdS
supergravity results which are known in terms of bulk to boundary propagator.
We expect that this reparametrization corresponds to transforming open string
moduli parameterization to the closed string ones.Comment: 23 pages, v2: calculations clarified, references added, v3: sections
re-arranged with more explanations, 4 figures and an appendix adde
Experimental studies of thorium ions implantation from pulse laser plasma into thin silicon oxide layers
We report the results of experimental studies related to implantation of
thorium ions into thin silicon dioxide by pulsed plasma fluxes expansion.
Thorium ions were generated by laser ablation from a metal target, and the
ionic component of the laser plasma was accelerated in an electric field
created by the potential difference (5, 10 and 15 kV) between the ablated
target and SiO2/Si(001) sample. Laser ablation system installed inside the
vacuum chamber of the electron spectrometer was equipped with YAG:Nd3+ laser
having the pulse energy of 100 mJ and time duration of 15 ns in the Q-switched
regime. Depth profile of thorium atoms implanted into the 10 nm thick
subsurface areas together with their chemical state as well as the band gap of
the modified silicon oxide at different conditions of implantation processes
were studied by means of X-ray photoelectron spectroscopy (XPS) and Reflected
Electron Energy Loss Spectroscopy (REELS) methods. Analysis of chemical
composition showed that the modified silicon oxide film contains complex
thorium silicates. Depending on local concentration of thorium atoms, the
experimentally established band gaps were located in the range of 6.0 - 9.0 eV.
Theoretical studies of optical properties of the SiO2 and ThO2 crystalline
systems have been performed by ab initio calculations within hybrid functional.
Optical properties of the SiO2/ThO2 composite were interpreted on the basis of
Bruggeman effective medium approximation. A quantitative assessment of the
yield of isomeric nuclei in "hot" laser plasma at the early stages of expansion
has been performed. The estimates made with experimental results demonstrated
that the laser implantation of thorium ions into the SiO2 matrix can be useful
for further research of low-lying isomeric transitions in 229Th isotope with
energy of 7.8(0.5) eV
Dimethyl dichloromalonate as a new synthetic equivalent of methyl dichloroacetate in the Darzens condensation
Dimethyl dichloromalonate reacts with aldehydes in the presence of sodium methoxide to form Ξ±-chloropyruvates, Ξ±-chloroglycidates, or Ξ±,Ξ±-dichlorohydrins, depending on the nature of the aldehyde. Β© 1995, Plenum Publishing Corporation. All rights reserved
Energy States of Colored Particle in a Chromomagnetic Field
The unitary transformation, which diagonalizes squared Dirac equation in a
constant chromomagnetic field is found. Applying this transformation, we find
the eigenfunctions of diagonalized Hamiltonian, that describe the states with
definite value of energy and call them energy states. It is pointed out that,
the energy states are determined by the color interaction term of the particle
with the background chromofield and this term is responsible for the splitting
of the energy spectrum.
We construct supercharge operators for the diagonal Hamiltonian, that ensure
the superpartner property of the energy states.Comment: 25 pages, some calculation details have been removed, typos correcte
Unoccupied Topological States on Bismuth Chalcogenides
The unoccupied part of the band structure of topological insulators
BiTeSe () is studied by angle-resolved two-photon
photoemission and density functional theory. For all surfaces
linearly-dispersing surface states are found at the center of the surface
Brillouin zone at energies around 1.3 eV above the Fermi level. Theoretical
analysis shows that this feature appears in a spin-orbit-interaction induced
and inverted local energy gap. This inversion is insensitive to variation of
electronic and structural parameters in BiSe and BiTeSe. In
BiTe small structural variations can change the character of the local
energy gap depending on which an unoccupied Dirac state does or does not exist.
Circular dichroism measurements confirm the expected spin texture. From these
findings we assign the observed state to an unoccupied topological surface
state
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