23,562 research outputs found
Spontaneous surface magnetization and chiral Majorana modes
Majorana fermions are often proposed to be realized by first singling out a
single non-degenerate Fermi surface in spin-orbit coupled systems, and then
imposing boundaries or defects. In this work, we take a different route
starting with two degenerate Fermi surfaces without spin-orbit coupling, and
show that by the method of "kink on boundary", the dispersive chiral Majorana
fermions can be realized in superconducting systems with pairings.
The surfaces of these systems develop spontaneous magnetizations whose
directions are determined by the boundary orientations and the phase difference
between the and -component gap functions. Along the magnetic domain
walls on the surface, there exist chiral Majorana fermions propagating
unidirectionally, which can be conveniently dragged and controlled by external
magnetic fields. Furthermore, the surface magnetization is shown to be a
magnetoelectric effect based on a Ginzburg-Landau free energy analysis. We also
discuss how to use the proximity effects to realize chiral Majorana fermions by
performing the "kink on boundary" method
Low-rank SIFT: An Affine Invariant Feature for Place Recognition
In this paper, we present a novel affine-invariant feature based on SIFT,
leveraging the regular appearance of man-made objects. The feature achieves
full affine invariance without needing to simulate over affine parameter space.
Low-rank SIFT, as we name the feature, is based on our observation that local
tilt, which are caused by changes of camera axis orientation, could be
normalized by converting local patches to standard low-rank forms. Rotation,
translation and scaling invariance could be achieved in ways similar to SIFT.
As an extension of SIFT, our method seeks to add prior to solve the ill-posed
affine parameter estimation problem and normalizes them directly, and is
applicable to objects with regular structures. Furthermore, owing to recent
breakthrough in convex optimization, such parameter could be computed
efficiently. We will demonstrate its effectiveness in place recognition as our
major application. As extra contributions, we also describe our pipeline of
constructing geotagged building database from the ground up, as well as an
efficient scheme for automatic feature selection
Localized direct CP violation in
We study the localized direct CP violation in the hadronic decays
,
including the effect caused by an interesting mechanism involving the charge
symmetry violating mixing between and . We calculate the
localized integrated direct CP violation when the low invariant mass of
[] is near . For five models of
form factors investigated, we find that the localized integrated direct CP
violation varies from -0.0170 to -0.0860 in the ranges of parameters in our
model when \,GeV. This result, especially the
sign, agrees with the experimental data and is independent of form factor
models. The new experimental data shows that the signs of the localized
integrated CP asymmetries in the regions \,GeV
and \,GeV are positive and negative,
respectively. We find that - mixing makes the localized
integrated CP asymmetry move towards the negative direction, and therefore
contributes to the sign change in those two regions. This behavior is also
model independent. We also calculate the localized integrated direct CP
violating asymmetries in the regions \,GeV and
\,GeV and find that they agree with the
experimental data in some models of form factors.Comment: 22 pages, 2 figures. arXiv admin note: text overlap with
arXiv:hep-ph/0602043, arXiv:hep-ph/0302156 by other author
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