7,416 research outputs found
Strong coupling in the Kondo problem in the low-temperature region
The magnetic field dependence of the average spin of a localized electron
coupled to conduction electrons with an antiferromagnetic exchange interaction
is found for the ground state. In the magnetic field range
( is the Kondo temperature) there is an inflection point, and in the
strong magnetic field range , the correction to the average spin
is proportional to . In zero magnetic field, the interaction
with conduction electrons also leads to the splitting of doubly degenerate spin
impurity states
Singular values of some modular functions
We study the properties of special values of the modular functions obtained
from Weierstrass P-function at imaginary quadratic points.Comment: 19 pages,corrected typo
Knight Shift Anomalies in Heavy Electron Materials
We calculate non-linear Knight Shift vs. susceptibility anomalies
for Ce ions possessing local moments in metals. The ions are modeled with the
Anderson Hamiltonian and studied within the non-crossing approximation (NCA).
The non-linearity diminishes with decreasing Kondo temperature
and nuclear spin- local moment separation. Treating the Ce ions as an
incoherent array in CeSn, we find excellent agreement with the observed Sn
data.Comment: 4 pages, Revtex, 3 figures available upon request from
[email protected]
Anderson Localization of Bogolyubov Quasiparticles in Interacting Bose-Einstein Condensates
We study the Anderson localization of Bogolyubov quasiparticles in an
interacting Bose-Einstein condensate (with healing length \xi) subjected to a
random potential (with finite correlation length \sigma_R). We derive
analytically the Lyapunov exponent as a function of the quasiparticle momentum
k and we study the localization maximum k_{max}. For 1D speckle potentials, we
find that k_{max} is proportional to 1/\xi when \xi is much larger than
\sigma_R while k_{max} is proportional to 1/\sigma_R when \xi is much smaller
than \sigma_R, and that the localization is strongest when \xi is of the order
of \sigma_R. Numerical calculations support our analysis and our estimates
indicate that the localization of the Bogolyubov quasiparticles is accessible
in current experiments with ultracold atoms.Comment: published version (no significant changes compared to last version
X(1812) in Quarkonia-Glueball-Hybrid Mixing Scheme
Recently a (X(1812)) state with a mass near the threshold of
and has been observed by the BES collaboration in decay. It has been suggested that it is a
state. If it is true, this state fits in a mixing scheme based on quarkonia,
glueball and hybrid (QGH) very nicely where five physical states are predicted.
Together with the known , , , and
states, X(1812) completes the five members in this family. Using known
experimental data on these particles we determine the ranges of the mixing
parameters and predict decay properties for X(1812). We also discuss some
features which may be able to distinguish between four-quark and hybrid mixing
schemes.Comment: 15 pages, 2 figures, 3 table
Strong correlation effects of the Re 5 electrons on the metal-insulator transition in CaFeReO
We have investigated the electronic structure of polycrystalline
CaFeReO using photoemission spectroscopy and band-structure
calculations within the local-density approximation+ (LDA+) scheme. In
valence-band photoemission spectra, a double-peak structure which is
characteristic of the metallic double perovskite series has been observed near
the Fermi level (), although it is less distinct compared to the
SrFeMoO case. The leading near- structure has a very weak
spectral weight at above the metal-insulator transition (MIT)
temperature of 140 K, and it loses the weight
below , forming a small energy gap.
To reproduce this small energy gap in the calculation, we require a very
large effective () for Re (4 eV) in addition to a relatively
large for Fe (4 eV). Although the most of the experimental
features can be interpreted with the help of the band theory, the overall
agreement between the theory and the experiment was not satisfactory. We
demonstrate that the effective transfer integral between Fe and Re is actually
smaller than that between Fe and Mo in CaFeMoO, which can explain both
MIT and very high ferrimagnetic transition temperature.Comment: 7 pages text, 5 figures, to be pulished in Phys. Rev.
KINEMATIC ANALYSIS OF THE UPPER LIMB AT DIFFERENT IMPACT HEIGHTS IN BASEBALL BATTING
The purpose of this study was to investigate the change in the upper limb motion to three different hitting areas of the strike zone: high, middle, and low. Subjects were ten right-handed male skilled batters of a university baseball team. Data were collected using a three dimensional automatic motion analysis system (Vicon 612). The joint angles of the upper limbs were computed. Comparison of the hitting in the high area vs. low area revealed that to hit the ball in the low area the batter more extended his left elbow, and flexed more his both shoulders and horizontal adduction angle of the left shoulder was large at the phase of the Left upper arm parallel (LUP). At the impact phase he flexed his left elbow more, adduction angle of the left shoulder was small in the case of the high area than the case of the low area. The opposite tendency to the high area was observed in the case of the low area
Disks around massive young stellar objects: are they common?
We present K-band polarimetric images of several massive young stellar
objects at resolutions 0.1-0.5 arcsec. The polarization vectors around
these sources are nearly centro-symmetric, indicating they are dominating the
illumination of each field. Three out of the four sources show elongated
low-polarization structures passing through the centers, suggesting the
presence of polarization disks. These structures and their surrounding
reflection nebulae make up bipolar outflow/disk systems, supporting the
collapse/accretion scenario as their low-mass siblings. In particular, S140
IRS1 show well defined outflow cavity walls and a polarization disk which
matches the direction of previously observed equatorial disk wind, thus
confirming the polarization disk is actually the circumstellar disk. To date, a
dozen massive protostellar objects show evidence for the existence of disks;
our work add additional samples around MYSOs equivalent to early B-type stars.Comment: 9 pages, including 2 figures, 1 table, to appear on ApJ
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