4,720 research outputs found
Implications of the dark axion portal for the muon g-2, B-factories, fixed target neutrino experiments and beam dumps
The dark axion portal is a recently introduced portal between the standard
model and the dark sector. It connects both the dark photon and the axion (or
axion-like particle) to the photon simultaneously through an anomaly triangle.
While the vector portal and the axion portal have been popular venues to search
for the dark photon and axion, respectively, the new portal provides new
detection channels if they coexist. The dark axion portal is not a result of
the simple combination of the two portals, and its value is not determined by
the other portal values; it should be tested independently. In this paper, we
discuss implications of the new portal for the leptonic g-2, B-factories, fixed
target neutrino experiments, and beam dumps. We provide the model-independent
constraints on the axion-photon-dark photon coupling and discuss the
sensitivities of the recently activated Belle-II experiment, which will play an
important role in testing the new portal.Comment: 14 pages, 12 figures. v2 - Additional discussion and references
added. v3 - Version accepted for publication by PRD. v4 - Correction to
equation following Eq. (15
On the origin of the hump structure in the in-plane optical conductivity of high Tc cuprates based on a SU(2) slave-boson theory
An improved version of SU(2) slave-boson approach is applied to study the
in-plane optical conductivity of the two dimensional systems of high Tc
cuprates. We investigate the role of fluctuations of both the phase and
amplitude of order parameters on the (Drude) peak-dip-hump structure in the
in-plane conductivity as a function of hole doping concentration and
temperature. The mid-infrared(MIR) hump in the in-plane optical conductivity is
shown to originate from the antiferromagnetic spin fluctuations of short
range(the amplitude fluctuations of spin singlet pairing order parameters),
which is consistent with our previous U(1) study. However the inclusion of both
the phase and amplitude fluctuations is shown to substantially improve the
qualitative feature of the optical conductivity by showing substantially
reduced Drude peak widths for entire doping range. Both the shift of the hump
position to lower frequency and the growth of the hump peak height with
increasing hole concentration is shown to be consistent with observations.Comment: 7 pages, 6 figure
GaIA: Graphical Information Gain based Attention Network for Weakly Supervised Point Cloud Semantic Segmentation
While point cloud semantic segmentation is a significant task in 3D scene
understanding, this task demands a time-consuming process of fully annotating
labels. To address this problem, recent studies adopt a weakly supervised
learning approach under the sparse annotation. Different from the existing
studies, this study aims to reduce the epistemic uncertainty measured by the
entropy for a precise semantic segmentation. We propose the graphical
information gain based attention network called GaIA, which alleviates the
entropy of each point based on the reliable information. The graphical
information gain discriminates the reliable point by employing relative entropy
between target point and its neighborhoods. We further introduce anchor-based
additive angular margin loss, ArcPoint. The ArcPoint optimizes the unlabeled
points containing high entropy towards semantically similar classes of the
labeled points on hypersphere space. Experimental results on S3DIS and
ScanNet-v2 datasets demonstrate our framework outperforms the existing weakly
supervised methods. We have released GaIA at https://github.com/Karel911/GaIA.Comment: WACV 2023 accepted pape
Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum
In many transition metal oxides (TMOs), oxygen stoichiometry is one of the
most critical parameters that plays a key role in determining the structural,
physical, optical, and electrochemical properties of the material. However,
controlling the growth to obtain high quality single crystal films having the
right oxygen stoichiometry, especially in a high vacuum environment, has been
viewed as a challenge. In this work, we show that through proper control of the
plume kinetic energy, stoichiometric crystalline films can be synthesized
without generating oxygen defects, even in high vacuum. We use a model
homoepitaxial system of SrTiO3 (STO) thin films on single crystal STO
substrates. Physical property measurements indicate that oxygen vacancy
generation in high vacuum is strongly influenced by the energetics of the laser
plume, and it can be controlled by proper laser beam delivery. Therefore, our
finding not only provides essential insight into oxygen stoichiometry control
in high vacuum for understanding the fundamental properties of STO-based thin
films and heterostructures, but expands the utility of pulsed laser epitaxy of
other materials as well
Strain-coupled ferroelectric polarization in BaTiO3-CaTiO3 superlattices
We report on growth and ferroelectric (FE) properties of superlattices (SLs)
composed of the FE BaTiO3 and the paraelectric (PE) CaTiO3. Previous theories
have predicted that the polarization in (BaTiO3)n/(CaTiO3)n SLs increases as
the sublayer thickness (n) increases when the same strain state is maintained.
However, our BaTiO3/CaTiO3 SLs show a varying lattice-strain state and
systematic reduction in polarization with increasing n while
coherently-strained SLs with n=1, 2 show a FE polarization of ca. 8.5 uC/cm^2.
We suggest that the strain coupling plays more important role in FE properties
than the electrostatic interlayer coupling based on constant dielectric
permittivities.Comment: 7 pages, 4 figure
Optical spectroscopic investigation on the coupling of electronic and magnetic structure in multiferroic hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films
We investigated the effects of temperature and magnetic field on the
electronic structure of hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films
using optical spectroscopy. As the magnetic ordering of the system was
disturbed, a systematic change in the electronic structure was commonly
identified in this series. The optical absorption peak near 1.7 eV showed an
unexpectedly large shift of more than 150 meV from 300 K to 15 K, accompanied
by an anomaly of the shift at the Neel temperature. The magnetic field
dependent measurement clearly revealed a sizable shift of the corresponding
peak when a high magnetic field was applied. Our findings indicated strong
coupling between the magnetic ordering and the electronic structure in the
multiferroic hexagonal RMnO3 compounds.Comment: 16 pages including 4 figure
- …