37,485 research outputs found
Dark matter for excess of AMS-02 positrons and antiprotons
We propose a dark matter explanation to simultaneously account for the excess
of antiproton-to-proton and positron power spectra observed in the AMS-02
experiment while having the right dark matter relic abundance and satisfying
the current direct search bounds. We extend the Higgs triplet model with a
hidden gauge symmetry of that is broken to by a quadruplet
scalar field, rendering the associated gauge bosons stable weakly-interacting
massive particle dark matter candidates. By coupling the complex Higgs triplet
and the quadruplet, the dark matter candidates can annihilate into
triplet Higgs bosons each of which in turn decays into lepton or gauge boson
final states. Such a mechanism gives rise to correct excess of positrons and
antiprotons with an appropriate choice of the triplet vacuum expectation value.
Besides, the model provides a link between neutrino mass and dark matter
phenomenology.Comment: 12 pages, 3 figures, references and comments added, version to appear
in Phys. Lett.
A Proximity-Aware Hierarchical Clustering of Faces
In this paper, we propose an unsupervised face clustering algorithm called
"Proximity-Aware Hierarchical Clustering" (PAHC) that exploits the local
structure of deep representations. In the proposed method, a similarity measure
between deep features is computed by evaluating linear SVM margins. SVMs are
trained using nearest neighbors of sample data, and thus do not require any
external training data. Clusters are then formed by thresholding the similarity
scores. We evaluate the clustering performance using three challenging
unconstrained face datasets, including Celebrity in Frontal-Profile (CFP),
IARPA JANUS Benchmark A (IJB-A), and JANUS Challenge Set 3 (JANUS CS3)
datasets. Experimental results demonstrate that the proposed approach can
achieve significant improvements over state-of-the-art methods. Moreover, we
also show that the proposed clustering algorithm can be applied to curate a set
of large-scale and noisy training dataset while maintaining sufficient amount
of images and their variations due to nuisance factors. The face verification
performance on JANUS CS3 improves significantly by finetuning a DCNN model with
the curated MS-Celeb-1M dataset which contains over three million face images
Advantages of the multinucleon transfer reactions based on 238U target for producing neutron-rich isotopes around N = 126
The mechanism of multinucleon transfer (MNT) reactions for producing
neutron-rich heavy nuclei around N = 126 is investigated within two different
theoretical frameworks: dinuclear system (DNS) model and isospin-dependent
quantum molecular dynamics (IQMD) model. The effects of mass asymmetry
relaxation, N=Z equilibration, and shell closures on production cross sections
of neutron-rich heavy nuclei are investigated. For the first time, the
advantages for producing neutron-rich heavy nuclei around N = 126 is found in
MNT reactions based on 238U target. We propose the reactions with 238U target
for producing unknown neutron-rich heavy nuclei around N = 126 in the future.Comment: 6 pages, 6 figure
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