12,823 research outputs found
Schroedinger functional formalism with domain-wall fermion
Finite volume renormalization scheme is one of the most fascinating scheme
for non-perturbative renormalization on lattice.
By using the step scaling function one can follow running of renormalized
quantities with reasonable cost.
It has been established the Schroedinger functional is very convenient to
define a field theory in a finite volume for the renormalization scheme.
The Schroedinger functional, which is characterized by a
Dirichlet boundary condition in temporal direction, is well defined and works
well for the Yang-Mills theory and QCD with the Wilson fermion.
However one easily runs into difficulties if one sets the same sort of the
Dirichlet boundary condition for the overlap Dirac operator or the domain-wall
fermion.
In this paper we propose an orbifolding projection procedure to impose the
Schroedinger functional Dirichlet boundary condition on the domain-wall
fermion.Comment: 32 page
Orbital Decay and Tidal Disruption of a Star Cluster: Analytical Calculation
The orbital decay and tidal disruption of a star cluster in a galaxy is
studied in an analytical manner. Owing to dynamical friction, the star cluster
spirals in toward the center of the galaxy. Simultaneously, the galactic tidal
field strips stars from the outskirts of the star cluster. Under an assumption
that the star cluster undergoes a self-similar evolution, we obtain the
condition and timescale for the star cluster to reach the galaxy center before
its disruption. The result is used to discuss the fate of so-called
intermediate-mass black holes with >10^3 M(sun) found recently in young star
clusters of starburst galaxies and also the mass function of globular clusters
in galaxies.Comment: 12 pages, 1 PS file for 2 figures, to appear in The Astrophysical
Journa
Inversion doublets of reflection-asymmetric clustering in 28Si and their isoscalar monopole and dipole transitions
[Background] Various cluster states of astrophysical interest are expected to
exist in the excited states of . However, they have not been
identified firmly, because of the experimental and theoretical difficulties.
[Purpose] To establish the Mg+, O+C and
Ne+2 cluster bands, we theoretically search for the
negative-parity cluster bands that are paired with the positive-parity bands to
constitute the inversion doublets. We also offer the isoscalar monopole and
dipole transitions as a promising probe for the clustering. We numerically show
that these transition strengths from the ground state to the cluster states are
very enhanced. [Method] The antisymmetrized molecular dynamics with Gogny D1S
effective interaction is employed to calculate the excited states of . The isoscalar monopole and dipole transition strengths are directly
evaluated from wave functions of the ground and excited states. [Results]
Negative-parity bands having Mg+ and O+C cluster
configurations are obtained in addition to the newly calculated
Ne+2 cluster bands. All of them are paired with the
corresponding positive-parity bands to constitute the inversion doublets with
various cluster configurations. The calculation show that the band-head of the
Mg+ and Ne+2 cluster bands are strongly excited
by the isoscalar monopole and dipole transitions. [Conclusions] The present
calculation suggests the existence of the inversion doublets with the
Mg+, O+C and Ne+2
configurations.Because of the enhanced transition strengths, we offer the
isoscalar monopole and dipole transitions as good probe for the
Mg+ and Ne+2 cluster bands.Comment: 28 pages, 8 figure
The spin gap of CaV4O9 revisited
The large-plaquette scenario of the spin gap in CaV4O9 is investigated on the
basis of extensive exact diagonalizations. We confirm the existence of a
large-plaquette phase in a wide range of parameters, and we show that the most
recent neutron scattering data actually require an intra-plaquette second
neighbor exchange integral much larger than the inter-plaquette one, thus
justifying the perturbative calculation used in the interpretation of the
neutron scattering experiments.Comment: 2 pages with 3 figure
Dynamical Gauge Boson and Strong-Weak Reciprocity
It is proposed that asymptotically nonfree gauge theories are consistently
interpreted as theories of composite gauge bosons. It is argued that when
hidden local symmetry is introduced, masslessness and coupling universality of
dynamically generated gauge boson are ensured. To illustrate these ideas we
take a four dimensional Grassmannian sigma model as an example and show that
the model should be regarded as a cut-off theory and there is a critical
coupling at which the hidden local symmetry is restored. Propagator and vertex
functions of the gauge field are calculated explicitly and existence of the
massless pole is shown. The beta function determined from the factor of
the dynamically generated gauge boson coincides with that of an asymptotic
nonfree elementary gauge theory. Using these theoretical machinery we construct
a model in which asymptotic free and nonfree gauge bosons coexist and their
running couplings are related by the reciprocally proportional relation.Comment: 19 pages, latex, 6 eps figures, a numbers of corrections are made in
the tex
Anthropogenic effects on subsurface temperature in Bangkok
International audienceSubsurface temperatures in Bangkok, where population and density increase rapidly, were analyzed to evaluate the effects of surface warming due to urbanization. The magnitude of surface warming evaluated from subsurface temperature in Bangkok was 1.7°C which agreed with meteorological data during the last 50 years. The depth apart from steady thermal gradient, which shows an indicator of the magnitude of surface warming due to additional heat from urbanization, was deeper at the center of the city than in the suburb areas of Bangkok. In order to separate surface warming effects into global warming effect and urbanization effect, analyses of subsurface temperature have been done depending on the distance from the city center. The results show that the expansion of urbanization in Bangkok reaches up to 80 km from the city center
Magnetism Localization in Spin-Polarized One-Dimensional Anderson-Hubbard Model
In order to study an interplay of disorder, correlation, and spin imbalance
on antiferromagnetism, we systematically explore the ground state of
one-dimensional spin-imbalanced Anderson-Hubbard model by using the
density-matrix renormalization group method. We find that disorders localize
the antiferromagnetic spin density wave induced by imbalanced fermions and the
increase of the disorder magnitude shrinks the areas of the localized
antiferromagnetized regions. Moreover, the antiferromagnetism finally
disappears above a large disorder. These behaviors are observable in atomic
Fermi gases loaded on optical lattices and disordered strongly-correlated
chains under magnetic field
Hole Localization in One-Dimensional Doped Anderson-Hubbard Model
We study the interplay of disorder and correlation in the one-dimensional
hole-doped Hubbard-model with disorder (Anderson-Hubbard model) by using the
density-matrix renormalization group method. Concentrating on the doped-hole
density profile, we find in a large regime that the clean system exhibits
a simple fluid-like behavior whereas finite disorders create locally Mott
regions which expand their area with increasing the disorder strength contrary
to the ordinary sense. We propose that such an anomalous Mott phase formation
assisted by disorder is observable in atomic Fermi gases by setup of the box
shape trap
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