43,643 research outputs found
A proposal for (0,2) mirrors of toric varieties
In this paper we propose (0,2) mirrors for general Fano toric varieties with
special tangent bundle deformations, corresponding to subsets of toric
deformations. Our mirrors are of the form of (B/2-twisted) (0,2)
Landau-Ginzburg models, matching Hori-Vafa mirrors on the (2,2) locus. We
compare our predictions to (0,2) mirrors obtained by Chen et al for certain
examples of toric varieties, and find that they match. We also briefly outline
conjectures for analogous results for hypersurfaces in Fano toric varieties.
Our methods utilize results from supersymmetric localization, which allows us
to incidentally gain occasional further insights into GLSM-based (2,2) mirror
constructions. For example, we explicitly verify that closed-string correlation
functions of the original A-twisted GLSM match those of the mirror B-twisted
Landau-Ginzburg model, as well as (0,2) deformations thereof.Comment: 52 pages, LaTeX; v2: miscellaneous writing updates, typos fixe
Scattering on two Aharonov-Bohm vortices with opposite fluxes
The scattering of an incident plane wave on two Aharonov-Bohm vortices with
opposite fluxes is considered in detail. The presence of the vortices imposes
non-trivial boundary conditions for the partial waves on a cut joining the two
vortices. These conditions result in an infinite system of equations for
scattering amplitudes between incoming and outgoing partial waves, which can be
solved numerically. The main focus of the paper is the analytic determination
of the scattering amplitude in two limits, the small flux limit and the limit
of small vortex separation. In the latter limit the dominant contribution comes
from the S-wave amplitude. Calculating it, however, still requires solving an
infinite system of equations, which is achieved by the Riemann-Hilbert method.
The results agree well with the numerical calculations
Baryon Destruction by Asymmetric Dark Matter
We investigate new and unusual signals that arise in theories where dark
matter is asymmetric and carries a net antibaryon number, as may occur when the
dark matter abundance is linked to the baryon abundance. Antibaryonic dark
matter can cause {\it induced nucleon decay} by annihilating visible baryons
through inelastic scattering. These processes lead to an effective nucleon
lifetime of 10^{29}-10^{32} years in terrestrial nucleon decay experiments, if
baryon number transfer between visible and dark sectors arises through new
physics at the weak scale. The possibility of induced nucleon decay motivates a
novel approach for direct detection of cosmic dark matter in nucleon decay
experiments. Monojet searches (and related signatures) at hadron colliders also
provide a complementary probe of weak-scale dark-matter--induced baryon number
violation. Finally, we discuss the effects of baryon-destroying dark matter on
stellar systems and show that it can be consistent with existing observations.Comment: 26 pages, 6 figure
Breaking the paradigm: Dr Insight empowers signature-free, enhanced drug repurposing
Motivation: Transcriptome-based computational drug repurposing has attracted considerable interest by bringing about faster and more cost-effective drug discovery. Nevertheless, key limitations of the current drug connectivity-mapping paradigm have been long overlooked, including the lack of effective means to determine optimal query gene signatures. Results: The novel approach Dr Insight implements a frame-breaking statistical model for the ‘hand-shake’ between disease and drug data. The genome-wide screening of concordantly expressed genes (CEGs) eliminates the need for subjective selection of query signatures, added to eliciting better proxy for potential disease-specific drug targets. Extensive comparisons on simulated and real cancer datasets have validated the superior performance of Dr Insight over several popular drug-repurposing methods to detect known cancer drugs and drug–target interactions. A proof-of-concept trial using the TCGA breast cancer dataset demonstrates the application of Dr Insight for a comprehensive analysis, from redirection of drug therapies, to a systematic construction of disease-specific drug-target networks
Group Theory of Chiral Photonic Crystals with 4-fold Symmetry: Band Structure and S-Parameters of Eight-Fold Intergrown Gyroid Nets
The Single Gyroid, or srs, nanostructure has attracted interest as a
circular-polarisation sensitive photonic material. We develop a group
theoretical and scattering matrix method, applicable to any photonic crystal
with symmetry I432, to demonstrate the remarkable chiral-optical properties of
a generalised structure called 8-srs, obtained by intergrowth of eight
equal-handed srs nets. Exploiting the presence of four-fold rotations, Bloch
modes corresponding to the irreducible representations E- and E+ are identified
as the sole and non-interacting transmission channels for right- and
left-circularly polarised light, respectively. For plane waves incident on a
finite slab of the 8-srs, the reflection rates for both circular polarisations
are identical for all frequencies and transmission rates are identical up to a
critical frequency below which scattering in the far field is restricted to
zero grating order. Simulations show the optical activity of the lossless
dielectric 8-srs to be large, comparable to metallic metamaterials,
demonstrating its potential as a nanofabricated photonic material
Group Theory of Circular-Polarization Effects in Chiral Photonic Crystals with Four-Fold Rotation Axes, Applied to the Eight-Fold Intergrowth of Gyroid Nets
We use group or representation theory and scattering matrix calculations to
derive analytical results for the band structure topology and the scattering
parameters, applicable to any chiral photonic crystal with body-centered cubic
symmetry I432 for circularly-polarised incident light. We demonstrate in
particular that all bands along the cubic [100] direction can be identified
with the irreducible representations E+/-,A and B of the C4 point group. E+ and
E- modes represent the only transmission channels for plane waves with wave
vector along the ? line, and can be identified as non-interacting transmission
channels for right- (E-) and left-circularly polarised light (E+),
respectively. Scattering matrix calculations provide explicit relationships for
the transmission and reflectance amplitudes through a finite slab which
guarantee equal transmission rates for both polarisations and vanishing
ellipticity below a critical frequency, yet allowing for finite rotation of the
polarisation plane. All results are verified numerically for the so-called
8-srs geometry, consisting of eight interwoven equal-handed dielectric Gyroid
networks embedded in air. The combination of vanishing losses, vanishing
ellipticity, near-perfect transmission and optical activity comparable to that
of metallic meta-materials makes this geometry an attractive design for
nanofabricated photonic materials
Radiative Neutrino Mass, Dark Matter and Leptogenesis
We propose an extension of the standard model, in which neutrinos are Dirac
particles and their tiny masses originate from a one-loop radiative diagram.
The new fields required by the neutrino mass-generation also accommodate the
explanation for the matter-antimatter asymmetry and dark matter in the
universe.Comment: 4 pages, 3 figures. Revised version with improved model. Accepted by
PR
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