833 research outputs found
Mutual Information and Boson Radius in c=1 Critical Systems in One Dimension
We study the generic scaling properties of the mutual information between two
disjoint intervals, in a class of one-dimensional quantum critical systems
described by the c=1 bosonic field theory. A numerical analysis of a spin-chain
model reveals that the mutual information is scale-invariant and depends
directly on the boson radius. We interpret the results in terms of correlation
functions of branch-point twist fields. The present study provides a new way to
determine the boson radius, and furthermore demonstrates the power of the
mutual information to extract more refined information of conformal field
theory than the central charge.Comment: 4.1 pages, 5 figure
CP^1+U(1) Lattice Gauge Theory in Three Dimensions: Phase Structure, Spins, Gauge Bosons, and Instantons
In this paper we study a 3D lattice spin model of CP Schwinger-bosons
coupled with dynamical compact U(1) gauge bosons. The model contains two
parameters; the gauge coupling and the hopping parameter of CP bosons. At
large (weak) gauge couplings, the model reduces to the classical O(3) (O(4))
spin model with long-range and/or multi-spin interactions. It is also closely
related to the recently proposed "Ginzburg-Landau" theory for quantum phase
transitions of quantum spin systems on a 2D square lattice at zero
temperature. We numerically study the phase structure of the model by
calculating specific heat, spin correlations, instanton density, and
gauge-boson mass. The model has two phases separated by a critical line of
second-order phase transition; O(3) spin-ordered phase and spin-disordered
phase. The spin-ordered phase is the Higgs phase of U(1) gauge dynamics,
whereas the disordered phase is the confinement phase. We find a crossover in
the confinement phase which separates dense and dilute regions of instantons.
On the critical line, spin excitations are gapless, but the gauge-boson mass is
{\it nonvanishing}. This indicates that a confinement phase is realized on the
critical line. To confirm this point, we also study the noncompact version of
the model. A possible realization of a deconfinement phase on the criticality
is discussed for the CP+U(1) model with larger .Comment: Discussion of finite size scaling, O(4) spin correlation adde
Exotic baryons from a heavy meson and a nucleon - Positive parity states -
We study heavy baryons with exotic flavor quantum numbers formed by a heavy
meson and a nucleon (DbarN and BN) with positive parity. One pion exchange
interaction, providing a tensor force, dominates as a long range force to bind
the DbarN and BN ystems. In the heavy quark mass limit, pseudoscalar meson and
vector meson are degenerate and the binding mechanism by the tensor force
analogous to that in the nuclear systems becomes important. As a result, we
obtain the DbarN and BN resonant states in the J^P=1/2^+, 3/2^+ and 5/2^+
channels with I=0
Reformulation of Boundary String Field Theory in terms of Boundary State
We reformulate bosonic boundary string field theory in terms of boundary
state. In our formulation, we can formally perform the integration of target
space equations of motion for arbitrary field configurations without assuming
decoupling of matter and ghost. Thus, we obtain the general form of the action
of bosonic boundary string field theory. This formulation may help us to
understand possible interactions between boundary string field theory and the
closed string sector.Comment: 13 page
Resonant critical coupling of surface lattice resonances with fluorescent absorptive thin film
Surface lattice resonance supported on nanoparticle arrays is a promising
candidate in enhancing fluorescent effects in both absorption and emission. The
optical enhancement provided by surface lattice resonance is primarily through
the light confinement beyond the diffraction limit, where the nanoparticle
arrays can enhance light-matter interaction for increased absorption as well as
providing more local density of states for enhanced spontaneous emission. In
this work, we optimize the in-coupling efficiency to the fluorescent molecules
by finding the conditions to maximize the absorption, also known as the
critical coupling condition. We studied the transmission characteristics and
the fluorescent emission of a nanoparticle array embedded in an
index-matching layer with fluorescent dye at various concentrations. A modified
coupled-mode theory that describes the nanoparticle array was then derived and
verified by numerical simulations. With the analytical model, we analyzed the
experimental measurements and discovered the condition to critically couple
light into the fluorescent dye, which is demonstrated as the strongest
emission. This study presents a useful guide for designing efficient energy
transfer from excitation beam to the emitters, which maximizes the external
conversion efficiency.Comment: 26 pages, 10 figure
Single-ion anisotropy in Haldane chains and form factor of the O(3) nonlinear sigma model
We consider spin-1 Haldane chains with single-ion anisotropy, which exists in
known Haldane chain materials. We develop a perturbation theory in terms of
anisotropy, where magnon-magnon interaction is important even in the low
temperature limit. The exact two-particle form factor in the O(3) nonlinear
sigma model leads to quantitative predictions on several dynamical properties
including dynamical structure factor and electron spin resonance frequency
shift. These agree very well with numerical results, and with experimental data
on the Haldane chain material Ni(CHN)N(PF)
Fabrication of submicron LaSrCuO intrinsic Josephson junction stacks
Intrinsic Josephson junction (IJJ) stacks of cuprate superconductors have
potential to be implemented as intrinsic phase qubits working at relatively
high temperatures. We report success in fabricating submicron
LaSrCuO (LSCO) IJJ stacks carved out of single crystals. We
also show a new fabrication method in which argon ion etching is performed
after focused ion beam etching. As a result, we obtained an LSCO IJJ stack in
which resistive multi-branches appeared. It may be possible to control the
number of stacked IJJs with an accuracy of a single IJJ by developing this
method.Comment: 5 pages, 6 figure
System Dynamics Model and Policy Scenario Analyses on International Movements of Indonesian Scientists and Engineers
. The necessity to face technology challenges in industrialization in Indonesia causes the current condition to be not preferable. Conditions in higher education which relates closely to the research and development in Indonesia trigger questions of what future holds in Indonesia's technology development in the future. This paper looks back at the previous literatures on International movements of scientists and engineers abroad and proposes to apply a causal loop diagram model. This paper also analyzes the relationships based on Indonesia's context and set a parameter for each variable. The relationships were checked through interview with representation from Indonesian research institutions and Ministry of Foreign Affairs. The result of this paper confirms that the diagram is able to symbolize the circumstances in Indonesia's context. Second important finding is that based on simulation and policy scenarios implemented, the policy to increase the number of scholarships by the government is predicted as the most effective to all important parameters for future development in Indonesia in relation to education and technology development, which will eventually lead to economic development
A Phase-Space Approach to Collisionless Stellar Systems Using a Particle Method
A particle method for reproducing the phase space of collisionless stellar
systems is described. The key idea originates in Liouville's theorem which
states that the distribution function (DF) at time t can be derived from
tracing necessary orbits back to t=0. To make this procedure feasible, a
self-consistent field (SCF) method for solving Poisson's equation is adopted to
compute the orbits of arbitrary stars. As an example, for the violent
relaxation of a uniform-density sphere, the phase-space evolution which the
current method generates is compared to that obtained with a phase-space method
for integrating the collisionless Boltzmann equation, on the assumption of
spherical symmetry. Then, excellent agreement is found between the two methods
if an optimal basis set for the SCF technique is chosen. Since this
reproduction method requires only the functional form of initial DFs but needs
no assumptions about symmetry of the system, the success in reproducing the
phase-space evolution implies that there would be no need of directly solving
the collisionless Boltzmann equation in order to access phase space even for
systems without any special symmetries. The effects of basis sets used in SCF
simulations on the reproduced phase space are also discussed.Comment: 16 pages w/4 embedded PS figures. Uses aaspp4.sty (AASLaTeX v4.0). To
be published in ApJ, Oct. 1, 1997. This preprint is also available at
http://www.sue.shiga-u.ac.jp/WWW/prof/hozumi/papers.htm
Virtual turning points and bifurcation of Stokes curves for higher order ordinary differential equations
For a higher order linear ordinary differential operator P, its Stokes curve
bifurcates in general when it hits another turning point of P. This phenomenon
is most neatly understandable by taking into account Stokes curves emanating
from virtual turning points, together with those from ordinary turning points.
This understanding of the bifurcation of a Stokes curve plays an important role
in resolving a paradox recently found in the Noumi-Yamada system, a system of
linear differential equations associated with the fourth Painleve equation.Comment: 7 pages, 4 figure
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