39,515 research outputs found
The wavefunction reconstruction effects in calculation of DM-induced electronic transition in semiconductor targets
The physics of the electronic excitation in semiconductors induced by sub-GeV
dark matter (DM) have been extensively discussed in literature, under the
framework of the standard plane wave (PW) and pseudopotential calculation
scheme. In this paper, we investigate the implication of the all-electron (AE)
reconstruction on estimation of the DM-induced electronic transition event
rates. As a benchmark study, we first calculate the wavefunctions in silicon
and germanium bulk crystals based on both the AE and pseudo (PS) schemes within
the projector augmented wave (PAW) framework, and then make comparisons between
the calculated excitation event rates obtained from these two approaches. It
turns out that in process where large momentum transfer is kinetically allowed,
the two calculated event rates can differ by a factor of a few. Such
discrepancies are found to stem from the high-momentum components neglected in
the PS scheme. It is thus implied that the correction from the AE wavefunction
in the core region is necessary for an accurate estimate of the DM-induced
transition event rate in semiconductors.Comment: A missing factor associated with the Fourier
transformation is added to both the AE and PS event rates in this version.
The ratio between the AE and PS event rates is not affecte
A Discriminatively Learned CNN Embedding for Person Re-identification
We revisit two popular convolutional neural networks (CNN) in person
re-identification (re-ID), i.e, verification and classification models. The two
models have their respective advantages and limitations due to different loss
functions. In this paper, we shed light on how to combine the two models to
learn more discriminative pedestrian descriptors. Specifically, we propose a
new siamese network that simultaneously computes identification loss and
verification loss. Given a pair of training images, the network predicts the
identities of the two images and whether they belong to the same identity. Our
network learns a discriminative embedding and a similarity measurement at the
same time, thus making full usage of the annotations. Albeit simple, the
learned embedding improves the state-of-the-art performance on two public
person re-ID benchmarks. Further, we show our architecture can also be applied
in image retrieval
Direct detection and solar capture of dark matter with momentum and velocity dependent elastic scattering
We explore the momentum and velocity dependent elastic scattering between the
dark matter (DM) particles and the nuclei in detectors and the Sun. In terms of
the non-relativistic effective theory, we phenomenologically discuss ten kinds
of momentum and velocity dependent DM-nucleus interactions and recalculate the
corresponding upper limits on the spin-independent DM-nucleon scattering cross
section from the current direct detection experiments. The DM solar capture
rate is calculated for each interaction. Our numerical results show that the
momentum and velocity dependent cases can give larger solar capture rate than
the usual contact interaction case for almost the whole parameter space. On the
other hand, we deduce the Super-Kamiokande's constraints on the solar capture
rate for eight typical DM annihilation channels. In contrast to the usual
contact interaction, the Super-Kamiokande and IceCube experiments can give more
stringent limits on the DM-nucleon elastic scattering cross section than the
current direct detection experiments for several momentum and velocity
dependent DM-nucleus interactions. In addition, we investigate the mediator
mass's effect on the DM elastic scattering cross section and solar capture
rate.Comment: 18 pages, 4 figures, 2 tables. minor changes and a reference added,
published in Nuclear Physics
A systematic study of the initial state in heavy ion collisions based on the quark participant assumption
We investigate the initial state geometric quantities of heavy ion collisions
based on the quark participant assumption in the Glauber multiple scattering
approach. A systematic comparison to the nucleon participant assumption has
been presented and confronted with the charged multiplicity measurements in
various collision systems. It is found that the quark participant based
assumption can be important to understand the data in multiplicity production
and the initial spatial eccentricity in small systems.Comment: 7 pages, 10 figure
Gapless edges of 2d topological orders and enriched monoidal categories
In this work, we give a precise mathematical description of a fully chiral
gapless edge of a 2d topological order (without symmetry). We show that the
observables on the 1+1D world sheet of such an edge consist of a family of
topological edge excitations, boundary CFT's and walls between boundary CFT's.
These observables can be described by a chiral algebra and an enriched monoidal
category. This mathematical description automatically includes that of gapped
edges as special cases. Therefore, it gives a unified framework to study both
gapped and gapless edges. Moreover, the boundary-bulk duality also holds for
gapless edges. More precisely, the unitary modular tensor category that
describes the 2d bulk phase is exactly the Drinfeld center of the enriched
monoidal category that describes the gapless/gapped edge. We propose a
classification of all gapped and fully chiral gapless edges of a given bulk
phase. In the end, we explain how modular-invariant bulk conformal field
theories naturally emerge on certain gapless walls between two trivial phases.Comment: 26 pages, 8 figures, An explanation of the appearance of boundary
CFT's on a chiral gapless edge, which is based on a generalized "no-go
theorem", is added. Final versio
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