3,407 research outputs found
Semiclassical Study on Tunneling Processes via Complex-Domain Chaos
We investigate the semiclassical mechanism of tunneling process in
non-integrable systems. The significant role of complex-phase-space chaos in
the description of the tunneling process is elucidated by studying a simple
scattering map model. Behaviors of tunneling orbits are encoded into symbolic
sequences based on the structure of complex homoclinic tanglement. By means of
the symbolic coding, the phase space itineraries of tunneling orbits are
related with the amounts of imaginary parts of actions gained by the orbits, so
that the systematic search of significant tunneling orbits becomes possible.Comment: 26 pages, 28 figures, submitted to Physical Review
Structure and apparent topography of TiO2 (110) surfaces
We present self-consistent ab-initio total-energy and electronic-structure
calculations on stoichiometric and non-stoichiometric TiO2 (110) surfaces.
Scanning tunneling microscopy (STM) topographs are simulated by calculating the
local electronic density of states over an energy window appropriate for the
experimental positive-bias conditions. We find that under these conditions the
STM tends to image the undercoordinated Ti atoms, in spite of the physical
protrusion of the O atoms, giving an apparent reversal of topographic contrast
on the stoichiometric 1x1 or missing-row 2x1 surface. We also show that both
the interpretation of STM images and the direct comparison of surface energies
favor an added-row structure over the missing-row structure for the
oxygen-deficient 2x1 surface.Comment: 6 pages, two-column style with 5 postscript figures embedded. Uses
REVTEX and epsf macros. Also available at
http://www.physics.rutgers.edu/~dhv/preprints/index.html#ng_tio
Multipole correlations of -orbital Hubbard model with spin-orbit coupling
We investigate the ground-state properties of a one-dimensional -orbital Hubbard model including an atomic spin-orbit coupling by using
numerical methods, such as Lanczos diagonalization and density-matrix
renormalization group. As the spin-orbit coupling increases, we find a
ground-state transition from a paramegnetic state to a ferromagnetic state. In
the ferromagnetic state, since the spin-orbit coupling mixes spin and orbital
states with complex number coefficients, an antiferro-orbital state with
complex orbitals appears. According to the appearance of the complex orbital
state, we observe an enhancement of octupole correlations.Comment: 3 pages, 3 figures, To appear in J. Phys. Soc. Jpn. Suppl.,
Proceedings of ICHE2010 (September 17-20, 2010, Hachioji, Japan
Superconductivity emerging near quantum critical point of valence transition
The nature of the quantum valence transition is studied in the
one-dimensional periodic Anderson model with Coulomb repulsion between f and
conduction electrons by the density-matrix renormalization group method. It is
found that the first-order valence transition emerges with the quantum critical
point and the crossover from the Kondo to the mixed-valence states is strongly
stabilized by quantum fluctuation and electron correlation. It is found that
the superconducting correlation is developed in the Kondo regime near the sharp
valence increase. The origin of the superconductivity is ascribed to the
development of the coherent motion of electrons with enhanced valence
fluctuation, which results in the enhancement of the charge velocity, but not
of the charge compressibility. Statements on the valence transition in
connection with Ce metal and Ce compounds are given.Comment: 9 pages, 4 figure
Deformed Hartree-Fock Calculation of Proton-Rich Nuclei
We perform Hartree-Fock+BCS calculations for even-even nuclei with 2 <= Z <=
82 and N ranging from outside the proton drip line to the experimental frontier
on the neutron-rich side. The ground state solutions are obtained for 737
nuclei, together with shape-coexistence solutions for 480 nuclei. Our method
features the Cartesian-mesh representation of single-particle wavefunctions,
which is advantageous in treating nucleon skins and exotic shapes. The results
are compared with those of the finite-range droplet model of Moller et al. as
well as the experimental values.Comment: 7 pages Latex, 5 postscript figures appended as uufil
Aligned Molecular Clouds towards SS433 and L=348.5 degrees; Possible Evidence for Galactic "Vapor Trail" Created by Relativistic Jet
We have carried out a detailed analysis of the NANTEN 12CO(J=1-0) dataset in
two large areas of ~25 square degrees towards SS433 (l~40 degree) and of ~18
square degrees towards l~348.5 degree, respectively. We have discovered two
groups of remarkably aligned molecular clouds at |b|~1--5 degree in the two
regions. In SS433, we have detected 10 clouds in total, which are well aligned
nearly along the axis of the X-ray jet emanating from SS433. These clouds have
similar line-of-sight velocities of 42--56 km s^-1 and the total projected
length of the feature is ~300 pc, three times larger than that of the X-ray
jet, at a distance of 3 kpc. Towards l~348.5 degree, we have detected four
clouds named as MJG348.5 at line-of-sight velocities of -80 -- -95 km s^-1 in
V_LSR, which also show alignment nearly perpendicular to the Galactic plane.
The total length of the feature is ~400 pc at a kinematic distance of 6 kpc. In
the both cases, the CO clouds are distributed at high galactic latitudes where
such clouds are very rare. In addition, their alignments and coincidence in
velocity should be even rarer, suggesting that they are physically associated.
We tested a few possibilities to explain these clouds, including protostellar
outflows, supershells, and interactions with energetic jets. Among them, a
favorable scenario is that the interaction between relativistic jet and the
interstellar medium induced the formation of molecular clouds over the last
~10^5-6 yrs. It is suggested that the timescale of the relativistic jet may be
considerably larger, in the order of 10^5-6 yrs, than previously thought in
SS433. The driving engine of the jet is obviously SS433 itself in SS433,
although the engine is not yet identified in MJG348.5 among possible several
candidates detected in the X-rays and TeV gamma rays.Comment: 29 pages, 10 figures, already published in PASJ, 2008,60, 71
Probing the Galactic cosmic ray flux with submillimeter and gamma ray data
The study of Galactic diffuse radiation combined with the knowledge
of the distribution of the molecular hydrogen in the Galaxy offers a unique
tool to probe the cosmic ray flux in the Galaxy. A methodology to study the
level of the cosmic ray "sea" and to unveil target-accelerator systems in the
Galaxy, which makes use of the data from the high resolution survey of the
Galactic molecular clouds performed with the NANTEN telescope and of the data
from gamma-ray instruments, has been developed. Some predictions concerning the
level of the cosmic ray "sea" and the -ray emission close to cosmic ray
sources for instruments such as Fermi and Cherenkov Telescope Array are
presented.Comment: Proceedings of the 4th Heidelberg International Symposium on High
Energy Gamma-Ray Astronom
Modeling the gamma-ray emission produced by runaway cosmic rays in the environment of RX J1713.7-3946
Diffusive shock acceleration in supernova remnants is the most widely invoked
paradigm to explain the Galactic cosmic ray spectrum. Cosmic rays escaping
supernova remnants diffuse in the interstellar medium and collide with the
ambient atomic and molecular gas. From such collisions gamma-rays are created,
which can possibly provide the first evidence of a parent population of runaway
cosmic rays. We present model predictions for the GeV to TeV gamma-ray emission
produced by the collisions of runaway cosmic rays with the gas in the
environment surrounding the shell-type supernova remnant RX J1713.7-3946. The
spectral and spatial distributions of the emission, which depend upon the
source age, the source injection history, the diffusion regime and the
distribution of the ambient gas, as mapped by the LAB and NANTEN surveys, are
studied in detail. In particular, we find for the region surrounding RX
J1713-3946, that depending on the energy one is observing at, one may observe
startlingly different spectra or may not detect any enhanced emission with
respect to the diffuse emission contributed by background cosmic rays. This
result has important implications for current and future gamma-ray experiments.Comment: version published on PAS
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