16,455 research outputs found
Lax forms of the -Painlev\'e equations
All -Painlev\'e equations which are obtained from the -analog of the
sixth Painlev\'e equation are expressed in a Lax formalism. They are
characterized by the data of the associated linear -difference equations.
The degeneration pattern from the -Painlev\'e equation of type is also
presented.Comment: 24 page
Comment on Ambiguities in the Holographic Weyl Anomaly
We consider possible ambiguities in the holographic Weyl anomaly that are
caused by local terms in the flow equation. We point out that such ambiguities
actually do not give physically meaningful contributions to the Weyl anomaly.Comment: LaTeX file, 7 pag
Single Impurity Anderson Model with Coulomb Repulsion between Conduction Electrons on the Nearest-Neighbour Ligand Orbital
We study how the Kondo effect is affected by the Coulomb interaction between
conduction electrons on the basis of a simplified model. The single impurity
Anderson model is extended to include the Coulomb interaction on the
nearest-neighbour ligand orbital. The excitation spectra are calculated using
the numerical renormalization group method. The effective bandwidth on the
ligand orbital, , is defined to classify the state. This quantity
decreases as the Coulomb interaction increases. In the
region, the low energy properties are described by the Kondo state, where
is the hybridization width. As decreases in this region, the
Kondo temperature is enhanced, and its magnitude becomes comparable to
for . In the region, the local
singlet state between the electrons on the and ligand orbitals is formed.Comment: 5 pages, 3 figures, LaTeX, to be published in J. Phys. Soc. Jpn Vol.
67 No.
Coexistence of vector chiral order and Tomonaga-Luttinger liquid in the frustrated three-leg spin tube in a magnetic field
The frustrated three-leg antiferromagnetic spin-1/2 tube with a weak
interchain coupling in a magnetic field is investigated by means of Abelian
bosonization techniques. It is clearly shown that a vector chiral order and a
one-component Tomonaga-Luttinger liquid coexist in a wide magnetic-field region
from a state with a small magnetization to a nearly saturated one. The chiral
order is predicted to still survive in the intermediate plateau state. We
further predict that (even) when the strength of one bond in the three rung
couplings is decreased (increased), an Ising type quantum phase transition
takes place and the chirality vanishes (no singular phenomena occur and the
chiral order is maintained). Even without magnetic fields, the chiral order
would also be present, if the spin tube possess easy-plane anisotropy.Comment: 6 pages, 4 figures, Revtex, published versio
Metamagnetism of antiferromagnetic XXZ quantum spin chains
The magnetization process of the one-dimensional antiferromagnetic Heisenberg
model with the Ising-like anisotropic exchange interaction is studied by the
exact diagonalization technique. It results in the evidence of the first-order
spin flop transition with a finite magnetization jump in the N\'eel ordered
phase for . It implies that the S=1/2 chain is an exceptional case
where the metamagnetic transition becomes second-order due to large quantum
fluctuations.Comment: 4 pages, Revtex, with 6 eps figure
Peculiar Velocities of Nonlinear Structure: Voids in McVittie Spacetime
As a study of peculiar velocities of nonlinear structure, we analyze the
model of a relativistic thin-shell void in the expanding universe. (1) Adopting
McVittie (MV) spacetime as a background universe, we investigate the dynamics
of an uncompensated void with negative MV mass. Although the motion itself is
quite different from that of a compensated void, as shown by Haines & Harris
(1993), the present peculiar velocities are not affected by MV mass. (2) We
discuss how precisely the formula in the linear perturbation theory applies to
nonlinear relativistic voids, using the results in (1) as well as the previous
results for the homogeneous background (Sakai, Maeda, & Sato 1993). (3) We
re-examine the effect of the cosmic microwave background radiation. Contrary to
the results of Pim & Lake (1986, 1988), we find that the effect is negligible.
We show that their results are due to inappropriate initial conditions. Our
results (1)-(3) suggest that the formula in the linear perturbation theory is
approximately valid even for nonlinear voids.Comment: 12 pages, aastex, 4 ps figures separate, Fig.2 added, to appear in
Ap
Analysis of atmospheric neutrino oscillations in three-flavor neutrinos
We analyze the atmospheric neutrino experiments of Super-Kamiokande (830-920
live days) using the three-flavor neutrino framework with the mass hierarchy
m_1 nearly equal m_2 << m_3. We study the sub-GeV, multi- GeV neutrinos and
upward through-going and stopping muons zenith angle distributions taking
account of the Earth matter effects thoroughly. We obtain the allowed regions
of mass and mixing parameters Delm^2_{23}, theta_{13} and theta_{23}.
Delm^2_{23} is restricted to 0.002-0.01eV^2 and theta_{13}<13degrees,
35degrees<theta_{23}<55degrees in 90% C.L. For theta_{12}, there is no
difference between the large angle solar neutrino solution and small one. From
chi^2 fit, the minimum chi^2=55(54DOF) is obtained at
Delm^2_{23}=4x10^(-3)eV^2, theta_{13}=10degrees and theta_{23} =45degrees.Comment: 16 pages, 3 figures, LaTe
Dark Matter Detection With Electron Neutrinos in Liquid Scintillation Detectors
We consider the prospects for liquid scintillation experiments (with a focus
on KamLAND) to detect the flux of electron neutrinos arising from dark matter
annihilation in the core of the sun. We show that, with data already taken,
KamLAND can provide the greatest sensitivity to the dark matter-proton
spin-dependent scattering cross-section for dark matter lighter than 20 GeV. It
is also possible to probe the dark matter-nucleon spin-independent scattering
cross-section for isospin-violating dark matter lighter than 10 GeV. KamLAND
can thus potentially confirm the dark matter interpretation of the DAMA and
CoGeNT signals, utilizing data already taken.Comment: 5 pages, 4 figures, PDFLaTeX; v2: references added, figures updated,
more detailed comparison of liquid scintillation and water Cerenkov detectors
(journal version
Critical properties of S=1/2 Heisenberg ladders in magnetic fields
The critical properties of the Heisenberg two-leg ladders are
investigated in a magnetic field. Combining the exact diagonalization method
and the finite-size-scaling analysis based on conformal field theory, we
calculate the critical exponents of spin correlation functions numerically. For
a strong interchain coupling, magnetization dependence of the critical
exponents shows characteristic behavior depending on the sign of the interchain
coupling. We also calculate the critical exponents for the Heisenberg
two-leg ladder with a diagonal interaction, which is thought as a model
Hamiltonian of the organic spin ladder compound
. Numerical results are compared with
experimental results of temperature dependence of the NMR relaxation rate
.Comment: REVTeX, 10 pages, 8 figures, accepted for Phys. Rev.
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