27 research outputs found
Revisit to Non-decoupling MSSM
Dipole operator requires the helicity
flip in the involving quark states thus the breaking of chiral . On the other hand, the -quark mass generation is also a
consequence of chiral symmetry breaking. Therefore,
in many models, there might be strong correlation between the
and quark Yukawa coupling. We use non-decoupling MSSM model to illustrate
this feature. The light Higgs boson may evade the direct search experiments at
LEPII or Tevatron while the 125 GeV Higgs-like boson is identified as the heavy
Higgs boson in the spectrum. A light charged Higgs is close to the heavy Higgs
boson which is of 125 GeV and its contribution to requires
large supersymmetric correction with large PQ and symmetry breaking. The
large supersymmetric contribution at the same time significantly modifies the
quark Yukawa co upling. With combined flavor constraints
and and direct constraints on Higgs properties, we
find best fit scenarios with light stop of (500 GeV), negative
around -750 GeV and large -term of 2-3 TeV. In addition, reduction in
partial width may also result in large enhancement of
decay branching fraction. Large parameter region in the survival space under
all bounds may be further constrained by if no excess of
is confirmed at LHC. We only identify a small parameter region with
significant decay that is consistent with all bounds and reduced
decay branching fraction.Comment: 18pages, 6 figure
Gamma-rays from Nearby Clusters: Constraints on Selected Decaying Dark Matter Models
Recently, the Fermi-LAT collaboration reported upper limits on the GeV
gamma-ray flux from nearby clusters of galaxies. Motivated by these limits, we
study corresponding constraints on gamma-ray emissions from two specific
decaying dark matter models, one via grand unification scale suppressed
operators and the other via R-parity violating operators. Both can account for
the PAMELA and Fermi-LAT excesses of e^\pm. For GUT decaying dark matter, the
gamma-rays from the M49 and Fornax clusters, with energy in the range of 1 to
10 GeV, lead to the most stringent constraints to date. As a result, this dark
matter is disfavored with conventional model of e^\pm background. In addition,
it is likely that some tension exists between the Fermi-LAT e^\pm excess and
the gamma ray constraints for any decaying dark matter model, provided
conventional model of e^\pm background is adopted. Nevertheless, the GUT
decaying dark matter can still solely account for the PAMELA positron fraction
excess without violating the gamma-ray constraints. For the gravitino dark
matter model with R-parity violation, cluster observations do not give tight
constraints. This is because a different e^\pm background has been adopted
which leads to relatively light dark matter mass around 200 GeV.Comment: 17 pages, 4 figures, version to appear in Phys. Lett.
Open World Classification with Adaptive Negative Samples
Open world classification is a task in natural language processing with key
practical relevance and impact. Since the open or {\em unknown} category data
only manifests in the inference phase, finding a model with a suitable decision
boundary accommodating for the identification of known classes and
discrimination of the open category is challenging. The performance of existing
models is limited by the lack of effective open category data during the
training stage or the lack of a good mechanism to learn appropriate decision
boundaries. We propose an approach based on \underline{a}daptive
\underline{n}egative \underline{s}amples (ANS) designed to generate effective
synthetic open category samples in the training stage and without requiring any
prior knowledge or external datasets. Empirically, we find a significant
advantage in using auxiliary one-versus-rest binary classifiers, which
effectively utilize the generated negative samples and avoid the complex
threshold-seeking stage in previous works. Extensive experiments on three
benchmark datasets show that ANS achieves significant improvements over
state-of-the-art methods.Comment: Accepted by EMNLP 2021 (Main Track, Long Paper
Reflection and transmission of Gaussian beam from a uniaxial crystal slab
We investigate the characteristics of Gaussian beams reflected and
transmitted from a uniaxial crystal slab with an arbitrary
orientation of its optical axis. The formulas of the total electric
and magnetic fields inside and outside the slab are derived by use
of Maxwell's equations and by matching the boundary conditions at
the interfaces. Numerical simulations are presented and the field
values as well as the power densities are computed. Negative
refractions are demonstrated when the beam is transmitted through a
uniaxial crystal slab. Beam splitting of the reflected beam is
observed and is explained by the resonant transmission for plane
waves. Dependences of the lateral shift on the incident angle and
beam width are discussed. Negative and positive lateral shifts are
observed due to the spatial anisotropic properties
Two-Step Adaptive Control for Planar Type Docking of Autonomous Underwater Vehicle
Planar type docking enables a convenient underwater energy supply for irregularly shaped autonomous underwater vehicles (AUVs), but the corresponding control method is still challenging. Conventional control methods for torpedo-shaped AUVs are not suitable for planar type docking due to the significant differences in system structures and motion characteristics. This paper proposes a two-step adaptive control method to solve the planar type docking problem. The method makes a seamless combination of horizontal dynamic positioning and visual servo docking considering ocean current disturbance. The current disturbance is estimated and canceled in the pre-docking step using a current observer, and the positioning error is further compensated for by the vertical visual servo technique in the docking step. Reduced order dynamic models are distinctively established for different docking steps according to the motion characteristics, based on which the dynamic controllers are designed considering the model parameter uncertainties. Simulation is conducted with an initial distance of 10 m in the horizontal direction and 3 m in depth. Stable and accurate dynamic positioning under up to 0.4 m/s of current disturbances with different directions is validated. A 0.5 m lateral positioning error is successfully compensated for by the visual servo docking step. The proposed control method provides a valuable reference for similar types of docking application
Downscaling of passive microwave soil moisture retrievals based on spectral analysis
The retrieval of soil moisture from passive microwave remotesensing data is presently one of the most effective methods for monitoring soil moisture. However, the spatial resolution of passive microwave soil moisture products is generally low; thus, existing soil moisture products should be downscaled in order to obtain more accurate soil moisture data. In this study, we explore the theoretical feasibility of applying the spectral downscaling method to the soil moisture in order to generate high spatial resolution soil moisture based on both Moderate Resolution Imaging Spectroradiometer and Fengyun-3B (FY3B) data. We analyse the spectral characteristics of soil moisture images covering the east-central of the Tibetan Plateau which have different spatial resolutions. The spectral analysis reveals that the spectral downscaling method is reliable in theory for downscaling soil moisture. So, we developed one spectral downscaling method for deriving the high spatial resolution (1 km) soil moister data from the FY3B data (25 km). Our results were compared with the ground truth measurements from 15 selected experimental days in 16 different sites. The average coefficient of determination (R2) of the spectral downscaling increased nearly doubled than that of the original FY3B soil moisture product. The spectral downscaled soil moister data were successfully applied to examine the water exchange between the land and atmosphere in the study regions. The spectral downscaling approach could be an efficient and effective method to improve the spatial resolution of current microwave soil moisture images.This work was supported by the National Natural Science Foundation of China (NSFC): [Grant
Number 41401426]
Composite of LiFePO \u3c inf\u3e 4 with titanium phosphate phases as lithium-ion battery electrode material
We report the synthesis of LiFePO4 (LFP) battery materials where during synthesis the iron has been substituted by up to 10 mol % with titanium. Analysis of the Ti-substituted materials revealed that at the substitution levels investigated, the Ti did not form a solid solution with the LFP, but rather minority phases containing Ti phosphates were formed and segregated at the nanoscopic scale. The minority phases were amorphous or not well-crystallized and accepted Li on first discharge in a lithium half cell, and solid state NMR spectra were consistent with one of the constituents being LiTi2(PO4)3. The Ti substituted materials had increased electrochemical capacities and discharge voltages relative to LFP prepared in an equivalent process, and the ability to accept Li on first discharge may find utility in using previously inaccessible capacity in battery cathode formulations and in balancing excess capacity from high energy cathode materials. © 2013 American Chemical Society