24,187 research outputs found
Multi-Trace Superpotentials vs. Matrix Models
We consider N = 1 supersymmetric U(N) field theories in four dimensions with
adjoint chiral matter and a multi-trace tree-level superpotential. We show that
the computation of the effective action as a function of the glueball
superfield localizes to computing matrix integrals. Unlike the single-trace
case, holomorphy and symmetries do not forbid non-planar contributions.
Nevertheless, only a special subset of the planar diagrams contributes to the
exact result. Some of the data of this subset can be computed from the large-N
limit of an associated multi-trace Matrix model. However, the prescription
differs in important respects from that of Dijkgraaf and Vafa for single-trace
superpotentials in that the field theory effective action is not the derivative
of a multi-trace matrix model free energy. The basic subtlety involves the
correct identification of the field theory glueball as a variable in the Matrix
model, as we show via an auxiliary construction involving a single-trace matrix
model with additional singlet fields which are integrated out to compute the
multi-trace results. Along the way we also describe a general technique for
computing the large-N limits of multi-trace Matrix models and raise the
challenge of finding the field theories whose effective actions they may
compute. Since our models can be treated as N = 1 deformations of pure N =2
gauge theory, we show that the effective superpotential that we compute also
follows from the N = 2 Seiberg-Witten solution. Finally, we observe an
interesting connection between multi-trace local theories and non-local field
theory.Comment: 35 pages, LaTeX, 6 EPS figures. v2: typos fixed, v3: typos fixed,
references added, Sec. 5 added explaining how multi-trace theories can be
linearized in traces by addition of singlet fields and the relation of this
approach to matrix model
Unsupervised Visible-Infrared Person ReID by Collaborative Learning with Neighbor-Guided Label Refinement
Unsupervised learning visible-infrared person re-identification (USL-VI-ReID)
aims at learning modality-invariant features from unlabeled cross-modality
dataset, which is crucial for practical applications in video surveillance
systems. The key to essentially address the USL-VI-ReID task is to solve the
cross-modality data association problem for further heterogeneous joint
learning. To address this issue, we propose a Dual Optimal Transport Label
Assignment (DOTLA) framework to simultaneously assign the generated labels from
one modality to its counterpart modality. The proposed DOTLA mechanism
formulates a mutual reinforcement and efficient solution to cross-modality data
association, which could effectively reduce the side-effects of some
insufficient and noisy label associations. Besides, we further propose a
cross-modality neighbor consistency guided label refinement and regularization
module, to eliminate the negative effects brought by the inaccurate supervised
signals, under the assumption that the prediction or label distribution of each
example should be similar to its nearest neighbors. Extensive experimental
results on the public SYSU-MM01 and RegDB datasets demonstrate the
effectiveness of the proposed method, surpassing existing state-of-the-art
approach by a large margin of 7.76% mAP on average, which even surpasses some
supervised VI-ReID methods
Poly[μ-5-ammonioisophthalato-aqua-μ-oxalato-dysprosium(III)]
The title complex, [Dy(C8H6NO4)(C2O4)(H2O)]n, is a dysprosium coordination polymer with mixed anions and was obtained under hydrothermal conditions. In the structure, the oxalate and 5-aminoisophthalate ligands link the dysprosium ions, building up a two-dimensional metal–organic framework parallel to the (10) plane. These sheets are further connected through O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, forming a three-dimensional supramolecular structure
Polyaniline coated micro-capillaries for continuous flow analysis of aqueous solutions
The inner walls of fused silica micro-capillaries were successfully coated with polyaniline nanofibres using the “grafting” approach. The optical response of polyaniline coatings was evaluated during the subsequent redoping–dedoping processes with hydrochloric acid and ammonia solutions, respectively, that were passed inside the micro-capillary in continuous flow. The optical absorbance of the polyaniline coatings was measured and analysed in the wavelength interval of [300–850 nm] to determine its optical sensitivity to different concentrations of ammonia. It was found that the optical properties of polyaniline coatings change in response toammonia solutions in a wide concentration range from 0.2 ppm to 2000 ppm. The polyaniline coatings employed as a sensing material for the optical detection of aqueous ammonia have a fast response time and a fast regeneration time of less than 5 seconds at room temperature. The coating was fully characterised by Scanning Electron Microscopy, Raman Spectroscopy, absorbance measurements and kinetic studies. The response of the coatings showed very good reproducibility, demonstrating that this platform can be used for the development of micro-capillary integrated sensors based on the inherited sensing properties of polyaniline
Collective modes in asymmetric ultracold Fermi systems
We derive the low energy effective action for the collective modes in systems
of fermions interacting via a short-range s-wave attraction, featuring unequal
chemical potentials for the two fermionic species (asymmetric systems). As a
consequence of the attractive interaction, fermions form a condensate that
spontaneously breaks the U(1) symmetry associated with total number
conservation. Therefore at sufficiently small temperatures and asymmetries, the
system is a superfluid. We reproduce previous results for the stability
conditions of the system as a function of the four-fermion coupling and
asymmetry. We obtain these results analyzing the coefficients of the low energy
effective Lagrangian of the modes describing fluctuations in the magnitude
(Higgs mode) and in the phase (Goldstone mode) of the difermion condensate. We
find that for certain values of parameters, the mass of the Higgs mode
decreases with increasing mismatch between the chemical potentials of the two
populations, if we keep the scattering length and the gap parameter constant.
Furthermore, we find that the energy cost for creating a position dependent
fluctuation of the condensate is constant in the gapped region and increases in
the gapless region. These two features may lead to experimentally detectable
effects. As an example, we argue that if the superfluid is put in rotation, the
square of the radius of the outer core of a vortex should sharply increase on
increasing the asymmetry, when we pass through the relevant region in the
gapless superfluid phase. Finally, by gauging the global U(1) symmetry, we
relate the coefficients of the effective Lagrangian of the Goldstone mode with
the screening masses of the gauge field.Comment: 41 pages, 6 figures. Expanded introduction, improved figures,
conclusions unchanged. Version to match the published versio
On the Sum Secrecy Rate of Multi-User Holographic MIMO Networks
The emerging concept of extremely-large holographic multiple-input
multiple-output (HMIMO), beneficial from compactly and densely packed
cost-efficient radiating meta-atoms, has been demonstrated for enhanced degrees
of freedom even in pure line-of-sight conditions, enabling tremendous
multiplexing gain for the next-generation communication systems. Most of the
reported works focus on energy and spectrum efficiency, path loss analyses, and
channel modeling. The extension to secure communications remains unexplored. In
this paper, we theoretically characterize the secrecy capacity of the HMIMO
network with multiple legitimate users and one eavesdropper while taking into
consideration artificial noise and max-min fairness. We formulate the power
allocation (PA) problem and address it by following successive convex
approximation and Taylor expansion. We further study the effect of fixed PA
coefficients, imperfect channel state information, inter-element spacing, and
the number of Eve's antennas on the sum secrecy rate. Simulation results show
that significant performance gain with more than 100\% increment in the high
signal-to-noise ratio (SNR) regime for the two-user case is obtained by
exploiting adaptive/flexible PA compared to the case with fixed PA
coefficients.Comment: 7 pages, 7 figures, submitted to IEEE ICC 202
2-[(4,6-Dimethoxypyrimidin-2-yl)oxy]benzaldehyde
In the title compound, C13H12N2O4, the dihedral angle between the benzene and pyrimidine rings is 55.57 (13)°. The carbonyl group and the two methoxyl groups are approximately coplanar with the benzene ring and pyrimidine ring; the C—C—C—O, C—O—C—N and C—O—C—C torsion angles being −6.1 (5), −4.8 (4) and 179.9 (3)°, respectively. In the crystal, molecules are linked via C—H⋯O interactions, forming chains propagating along [110]
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