946 research outputs found
Truncation of lattice fractional quantum Hall Hamiltonians derived from conformal field theory
Conformal field theory has recently been applied to derive few-body
Hamiltonians whose ground states are lattice versions of fractional quantum
Hall states. The exact lattice models involve interactions over long distances,
which is difficult to realize in experiments. It seems, however, that such
long-range interactions should not be necessary, as the correlations decay
exponentially in the bulk. This poses the question, whether the Hamiltonians
can be truncated to contain only local interactions without changing the
physics of the ground state. Previous studies have in a couple of cases with
particularly much symmetry obtained such local Hamiltonians by keeping only a
few local terms and numerically optimizing the coefficients. Here, we
investigate a different strategy to construct truncated Hamiltonians, which
does not rely on optimization, and which can be applied independent of the
choice of lattice. We test the approach on two models with bosonic
Laughlin-like ground states with filling factor and , respectively.
We first investigate how the coupling strengths in the exact Hamiltonians
depend on distance, and then we study the truncated models. For the case of
filling, we find that the truncated model with truncation radius
lattice constants on the square lattice and lattice constant on
the triangular lattice has an approximate twofold ground state degeneracy on
the torus, and the overlap per site between these states and the states
constructed from conformal field theory is higher than for the lattices
considered. For the model at filling, our results give some hints that a
truncation radius of on the square lattice and on the
triangular lattice might be enough, but the finite size effects are too large
to judge whether the topology is, indeed, present in the thermodynamic limit.Comment: 8 Pages, 10 Figure
Post-Pandemic Sustainable Business Solution
Copyright © 2021 The Author(s). In this research, we examined some of the key concerns faced by businesses from various industries which are associated with the COVID-19 pandemic. To extend the existing research, we also evaluate perspectives on sustainable recovery solutions proposed by the business. This market research, supported by academic research, is intended to support businesses and the Government in tapering their approach to achieving sustainable economic recovery. A total of 16 different industries participated in our research project and the findings of our research provide an evidence-based perspective on how businesses are responding to the pandemic and planning for the post-COVID era. This evidence document outlines recommendations on potential support packages and areas of focus for the Government to consider, based on recent survey data, lessons learnt from the past, professional experience and respected academic models.This research received no external fundin
Ultraviolet Extinction Properties in the Milky Way
We have assembled a homogeneous database of 417 ultraviolet (UV) extinction
curves for reddened sightlines having International Ultraviolet Explorer (IUE)
spectra. We have combined these with optical and 2MASS photometry allowing
estimates of the ratio of total-to-selective extinction, R(V), for the entire
sample. Fitzpatrick-Massa (FM) parameters have also been found for the entire
sample. This is the largest study of parameterized UV extinction curves yet
published and it covers a wide range of environments, from dense molecular
clouds to the diffuse interstellar medium (ISM), with extinctions A(V) ranging
from 0.50 to 4.80. It is the first to extend far beyond the solar neighborhood
and into the Galaxy at large, with 30 sightlines having distances > 5 kpc.
Previously, the longest sightlines with FM parameters and R(V) extended ~ 1
kpc. We find that (1.) the CCM extinction law applies for 93% of the
sightlines, implying that dust processing in the Galaxy is efficient and
systematic; (2.) the central wavelength of the 2175 A bump is constant; (3.)
the 2175 A bump width is dependent on environment. Only four sightlines show
systematic deviations from CCM, HD 29647, 62542, 204827, and 210121. These
sightlines all sample dense, molecule-rich clouds. The new extinction curves
and values of R(V) allow us to revise the CCM law.Comment: 32 pages, 12 figure
Design space exploration for providing QoS within the HARMONY framework
ABSTRACT The HARMONY architectur
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