61,539 research outputs found
QCD Sum Rule for S_{11}(1535)
We propose a new interpolating field for S(1535) to determine its mass
from QCD sum rules. In the nonrelativistic limit, this interpolating field
dominantly reduces to two quarks in the s-wave state and one quark in the
p-wave state. An optimization procedure, which makes use of a duality relation,
yields the interpolating field which overlaps strongly with the negative-parity
baryon and at the same time does not couple at all to the low lying
positive-parity baryon. Using this interpolating field and applying the
conventional QCD sum rule analysis, we find that the mass of S is
reasonably close to the experimentally known value, even though the precise
determination depends on the poorly known quark-gluon condensate. Hence our
interpolating field can be used to investigate the spectral properties of
S(1535).Comment: 12 pages, Revtex, 1 ps figure available from author
symmetry restoration in QCD with flavors
Recently, there have been reports that the chirally restored phase of QCD is
effectively symmetric under rather than . We supplement their argument by including the contributions from
topologically nontrivial gauge field configurations and discuss how the
conclusions are modified. General statements are made concerning the particle
spectrum of QCD with light flavors in the high temperature chirally
restored phase.Comment: 6 pages, no figures, revte
Visual-hint Boundary to Segment Algorithm for Image Segmentation
Image segmentation has been a very active research topic in image analysis
area. Currently, most of the image segmentation algorithms are designed based
on the idea that images are partitioned into a set of regions preserving
homogeneous intra-regions and inhomogeneous inter-regions. However, human
visual intuition does not always follow this pattern. A new image segmentation
method named Visual-Hint Boundary to Segment (VHBS) is introduced, which is
more consistent with human perceptions. VHBS abides by two visual hint rules
based on human perceptions: (i) the global scale boundaries tend to be the real
boundaries of the objects; (ii) two adjacent regions with quite different
colors or textures tend to result in the real boundaries between them. It has
been demonstrated by experiments that, compared with traditional image
segmentation method, VHBS has better performance and also preserves higher
computational efficiency.Comment: 45 page
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