527 research outputs found
Topology and Interactions in a Frustrated Slab: Tuning from Weyl Semimetals to C > 1 Fractional Chern Insulators
We show that, quite generically, a [111] slab of spin-orbit coupled
pyrochlore lattice exhibits surface states whose constant energy curves take
the shape of Fermi arcs, localized to different surfaces depending on their
quasimomentum. Remarkably, these persist independently of the existence of Weyl
points in the bulk. Considering interacting electrons in slabs of finite
thickness, we find a plethora of known fractional Chern insulating phases, to
which we add the discovery of a new higher Chern number state which is likely a
generalization of the Moore-Read fermionic fractional quantum Hall state. By
contrast, in the three-dimensional limit, we argue for the absence of gapped
states of the flat surface band due to a topologically protected coupling of
the surface to gapless states in the bulk. We comment on generalizations as
well as experimental perspectives in thin slabs of pyrochlore iridates.Comment: Published. 6+4 page
Semi-classical Characters and Optical Model Description of Heavy Ion Scattering, Direct Reactions, and Fusion at Near-barrier Energies
An approach is proposed to calculate the direct reaction (DR) and fusion
probabilities for heavy ion collisions at near-Coulomb-barrier energies as
functions of the distance of closest approach D within the framework of the
optical model that introduces two types of imaginary potentials, DR and fusion.
The probabilities are calculated by using partial DR and fusion cross sections,
together with the classical relations associated with the Coulomb trajectory.
Such an approach makes it possible to analyze the data for angular
distributions of the inclusive DR cross section, facilitating the determination
of the radius parameters of the imaginary DR potential in a less ambiguous
manner. Simultaneous -analyses are performed of relevant data for the
O+Pb system near the Coulomb-barrier energy
A Novel Method for the Solution of the Schroedinger Eq. in the Presence of Exchange Terms
In the Hartree-Fock approximation the Pauli exclusion principle leads to a
Schroedinger Eq. of an integro-differential form. We describe a new spectral
noniterative method (S-IEM), previously developed for solving the
Lippman-Schwinger integral equation with local potentials, which has now been
extended so as to include the exchange nonlocality. We apply it to the
restricted case of electron-Hydrogen scattering in which the bound electron
remains in the ground state and the incident electron has zero angular
momentum, and we compare the acuracy and economy of the new method to three
other methods. One is a non-iterative solution (NIEM) of the integral equation
as described by Sams and Kouri in 1969. Another is an iterative method
introduced by Kim and Udagawa in 1990 for nuclear physics applications, which
makes an expansion of the solution into an especially favorable basis obtained
by a method of moments. The third one is based on the Singular Value
Decomposition of the exchange term followed by iterations over the remainder.
The S-IEM method turns out to be more accurate by many orders of magnitude than
any of the other three methods described above for the same number of mesh
points.Comment: 29 pages, 4 figures, submitted to Phys. Rev.
The future size and composition of the private rented sector: an LSE London project for Shelter
Current forecasts suggest that perhaps one in four households in England and maybe one in three in London might be living in the private rented sector by 2025. However, there has been little attempt to identify which household types are likely to be most affected. The brief for this study was both to fill this gap and to look somewhat further ahead. Shelter has asked LSE London to ‘produce plausible modelling, forecasting how many privately renting households there will be in England in 2028, what their demographic composition will be and what proportion of each demographic group will be privately renting.’ The findings would be used to provide an evidence base from which to discuss how policy towards the private rented sector might better serve the full range of households likely to be living in the sector
Tuning from Weyl Semimetals to C>1 Fractional Chern Insulators
We show that, quite generically, a [111] slab of spin-orbit coupled pyrochlore
lattice exhibits surface states whose constant energy curves take the shape of
Fermi arcs, localized to different surfaces depending on their quasimomentum.
Remarkably, these persist independently of the existence of Weyl points in the
bulk. Considering interacting electrons in slabs of finite thickness, we find
a plethora of known fractional Chern insulating phases, to which we add the
discovery of a new higher Chern number state which is likely a generalization
of the Moore-Read fermionic fractional quantum Hall state. By contrast, in the
three-dimensional limit, we argue for the absence of gapped states of the flat
surface band due to a topologically protected coupling of the surface to
gapless states in the bulk. We comment on generalizations as well as
experimental perspectives in thin slabs of pyrochlore iridates
Number of Circulating CD14-Positive Cells and the Serum Levels of TNF-α Are Raised in Acute Charcot Foot
International audienc
Simultaneous Optical Model Analyses of Elastic Scattering, Breakup, and Fusion Cross Section Data for the He + Bi System at Near-Coulomb-Barrier Energies
Based on an approach recently proposed by us, simultaneous
-analyses are performed for elastic scattering, direct reaction (DR)
and fusion cross sections data for the He+Bi system at
near-Coulomb-barrier energies to determine the parameters of the polarization
potential consisting of DR and fusion parts. We show that the data are well
reproduced by the resultant potential, which also satisfies the proper
dispersion relation. A discussion is given of the nature of the threshold
anomaly seen in the potential
Projectile Excitations in Reactions
It has recently been proven from measurements of the spin-transfer
coefficients and that there is a small but non-vanishing
component , in the inclusive reaction
cross section . It is shown that the dominant part of the measured
can be explained in terms of the projectile excitation
mechanism. An estimate is further made of contributions to from
s-wave rescattering process. It is found that s-wave rescattering contribution
is much smaller than the contribution coming from projectile
excitation mechanism. The addition of s-wave rescattering contribution to the
dominant part, however, improves the fit to the data.Comment: 9 pages, Revtex, figures can be obtained upon reques
Phenomenological local potentials for \pi^- + ^{12}C scattering from 120 to 766 MeV
Pion-nucleus scattering cross sections are calculated by solving a
Schr\"{o}dinger equation reduced from the Klein-Gordon equation. Local
potentials are assumed, and phenomenological potential parameters are searched
energy-dependently for C system so as to reproduce not only
elastic differential cross sections but also total elastic, reaction and total
cross sections at 13 pion incident energies from 120 to 766 MeV. The real and
imaginary parts of the local potentials thus obtained are shown to satisfy the
dispersion relation. The imaginary part of the potentials as a function of the
pion energy is found to peak near the (1232)-resonance energy. The
strong absorption radius of the pion projectile with incident energies near the
-resonance region is found to be about fm, which is
consistent with previous studies of the region where the decay of the
's takes place in nuclei. The phenomenological local potentials are
then compared with the local potentials exactly phase-shift equivalent to
Kisslinger potentials for pion energies near the -resonance
Dynamic susceptibility of a spin ice near the critical point
We consider spin ice magnets (primarily, ) in the
vicinity of their critical point on the plane. We find that the
longitudinal susceptibility diverges at the critical point, leading to the
behaviour qualitatively similar to the one which would result from non-zero
conductance of magnetic charges. We show that dynamics of critical fluctuations
belongs to the universality class of easy-axis ferroelectric and calculate
logarithmic corrections (within two-loop approximation) to the mean-field
critical behavior.Comment: 5 pages, 3 figures. Some misprints are corrected, among them are the
formula (20) and the estimation for $\Gamma_c
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