14,517 research outputs found
Superconformal defects in the tricritical Ising model
We study superconformal defect lines in the tricritical Ising model in 2
dimensions. By the folding trick, a superconformal defect is mapped to a
superconformal boundary of the N=1 superconformal unitary minimal model of
c=7/5 with D_6-E_6 modular invariant. It turns out that the complete set of the
boundary states of c=7/5 D_6-E_6 model cannot be interpreted as the consistent
set of superconformal defects in the tricritical Ising model since it does not
contain the "no defect" boundary state. Instead, we find a set of 18 consistent
superconformal defects including "no defect" and satisfying the Cardy
condition. This set also includes some defects which are not purely
transmissive or purely reflective.Comment: 25 pages, 3 figures. v2: typos corrected. v3: clarification about
spin structure aligned theory added, references adde
Towards More Precise Photometric Redshifts: Calibration Via CCD Photometry
We present the initial results from a deep, multi-band photometric survey of
selected high Galactic latitude redshift fields. Previous work using the
photographic data of Koo and Kron demonstrated that the distribution of
galaxies in the multi-dimensional flux space U B R I is nearly planar. The
position of a galaxy within this plane is determined by its redshift,
luminosity and spectral type. Using recently acquired deep CCD photometry in
existing, published redshift fields, we have redetermined the distribution of
galaxies in this four-dimensional magnitude space. Furthermore, from our CCD
photometry and the published redshifts, we have quantified the
photometric-redshift relation within the standard AB magnitude system. This
empirical relation has a measured dispersion of approximately 0.02 for z < 0.4.
With this work we are reaching the asymptotic intrinsic dispersions that were
predicted from simulated distributions of galaxy colors.Comment: submitted to the Astrophysical Journal Letter
Permutation branes and linear matrix factorisations
All the known rational boundary states for Gepner models can be regarded as
permutation branes. On general grounds, one expects that topological branes in
Gepner models can be encoded as matrix factorisations of the corresponding
Landau-Ginzburg potentials. In this paper we identify the matrix factorisations
associated to arbitrary B-type permutation branes.Comment: 43 pages. v2: References adde
Fatigue delamination behaviour of unidirectional carbon fibre/epoxy laminates reinforced by Z-Fiber® pinnin
-Pin reinforced carbon-fibre epoxy laminates were tested under Mode I and Mode
II conditions, both quasi-statically and in fatigue. Test procedures were
adapted from existing standard or pre-standard tests. Samples containing 2% and
4% areal densities of carbon-fibre Z-pins (0.28mm diameter) were compared with
unpinned laminates. Quasi-static tests under displacement control yielded a
dramatic increase of the apparent delamination resistance. Specimens with 2% pin
density failed in Mode I at loads 170N, equivalent to an apparent GIC of 2kJ/m2.
Fatigue testing under load control showed that the presence of the through-
thickness reinforcement slowed down fatigue delamination propagation
Experimental Quantum Teleportation with a 3-Bell-state Analyzer
We present a Bell-state analyzer for time-bin qubits allowing the detection
of three out of four Bell-states with linear optics, two detectors and no
auxiliary photons. The theoretical success rate of this scheme is 50%. A
teleportation experiment was performed to demonstrate its functionality. We
also present a teleportation experiment with a Fidelity larger than the cloning
limit of F=5/6.Comment: 11 pages, 14 figure
Can one see entanglement ?
The human eye can detect optical signals containing only a few photons. We
investigate the possibility to demonstrate entanglement with such biological
detectors. While one person could not detect entanglement by simply observing
photons, we discuss the possibility for several observers to demonstrate
entanglement in a Bell-type experiment, in which standard detectors are
replaced by human eyes. Using a toy model for biological detectors that
captures their main characteristic, namely a detection threshold, we show that
Bell inequalities can be violated, thus demonstrating entanglement. Remarkably,
when the response function of the detector is close to a step function, quantum
non-locality can be demonstrated without any further assumptions. For smoother
response functions, as for the human eye, post-selection is required.Comment: 5 pages, 5 figure
The National Virtual Observatory
As a scientific discipline, Astronomy is rather unique. We only have one
laboratory, the Universe, and we cannot, of course, change the initial
conditions and study the resulting effects. On top of this, acquiring
Astronomical data has historically been a very labor-intensive effort. As a
result, data has traditionally been preserved for posterity. With recent
technological advances, however, the rate at which we acquire new data has
grown exponentially, which has generated a Data Tsunami, whose wave train
threatens to overwhelm the field. In this conference proceedings, we present
and define the concept of virtual observatories, which we feel is the only
logical answer to this dilemma.Comment: 5 pages, uses newpasp.sty (included), to appear in "Extragalactic Gas
at Low Redshfit", ASP Conf. Series, J. S. Mulchaey and J. T. Stocke (eds.
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