1,961 research outputs found
Multi-phases in gauge theories on non-simply connected spaces
It is pointed out that phase structures of gauge theories compactified on
non-simply connected spaces are not trivial. As a demonstration, an SU(2) gauge
model on is studied and is shown to possess three phases:
Hosotani, Higgs and coexisting phases. The critical radius and the order of the
phase transitions are explicitly determined. A general discussion about phase
structures for small and large scales of compactified spaces is given. The
appearance of phase transitions suggests a GUT scenario in which the gauge
hierarchy problem is replaced by a dynamical problem of how to stabilize a
radius of a compactified space in close vicinity to a critical radius.Comment: 12 pages, 1 figur
Multi-phases in gauge theories of non-simply connected spaces
It is pointed out that phase structures of gauge theories compactified on non-simply connected spaces are not trivial. As a demonstration, an SU(2) gauge model on M^3 ⊗ S^1 is studied, and it is shown to possess three phases: Hosotani, Higgs and coexisting phases. The critical radius and the order of the phase transitions are determined explicitly. A general discussion about phase structures for small and large scales of compactified spaces is given. The appearance of phase transitions suggests a GUT scenario in which the gauge hierarchy problem is replaced by the dynamical problem of the stabilization of the radius of a compactified space in the vicinity of a critical radius
Finite Higgs mass without Supersymmetry
We identify a class of chiral models where the one-loop effective potential
for Higgs scalar fields is finite without any requirement of supersymmetry. It
corresponds to the case where the Higgs fields are identified with the
components of a gauge field along compactified extra dimensions. We present a
six dimensional model with gauge group U(3)xU(3) and quarks and leptons
accomodated in fundamental and bi-fundamental representations. The model can be
embedded in a D-brane configuration of type I string theory and, upon
compactification on a T^2/Z_2 orbifold, it gives rise to the standard model
with two Higgs doublets.Comment: 28 pages, 4 figures, uses axodraw. Some typos corrected and
references rearrange
Five steps in leukocyte extravasation in the microcirculation by chemoattractants
For in vivo study of the phenomena observed in vitro, PMN (polymorphonuclear leukocyte) extravasation was analysed quantitatively in the microcirculation of the hamster cheek pouch using a video system. Topical application of leukotriene B4 or N-formyl-methionylleucyl- phenylalanine increased dose dependently the number of PMNs adhering to the venules. Eighty to 90% of the adhering PMNs disappeared from the vascular lumen into the venular wall within 10-12 rain after the adhesion. After PMNs had passed through the endothelial cell layer, they remained in the venular wall for more than 30 min after application of the chemoattractants and appeared in the extravascular space. Thus, the process could be divided into five steps: (1) rolling and (2) adhesion to the endothelium, (3) passage through the endothelial layer (4) remaining in the venular wall, and (5) passage through the basement membrane
Inhibition of neutrophil migration by a selective inhibitor of matrix metalloproteinase: analysis by intravital microscopy
Observation of the microcirculation of the hamster cheek pouch by intravital microscopy revealed five steps of neutrophil migration from the venules after topical application of leukotriene B4 to the microvasculature: rolling along the venular wall (Step 1), adhesion to it (Step 2), disappearance from the vascular lumen (Step 3), presence between the endothelial cells and the subendothelial basement membrane (Step 4) and passage through the basement membrane (Step 5). The present study was performed to examine whether a metalloproteinase inhibitor inhibits neutrophil migration at any of the above five steps. Chymostatin and leupeptin did not inhibit any of these five steps. In contrast, FN-439, a selective inhibitor of matrix metalloproteinase, reduced the number of neutrophils in the perivascular space without affecting Steps 1 to 3. It was concluded that neutrophils may use metalloproteinase (collagenase/gelatinase) to penetrate the subendothelial basement membrane
Asymmetry Parameter of the by Analyzing the Transition Form Factors within QCD
Separating the mixture of the and states, the
transition form factors are calculated in
the three-point QCD sum rules approach. The longitudinal, transverse and total
decay widths as well as the asymmetry parameter, characterizing the
polarization of the axial and the branching ratio for these
decays are evaluated.Comment: 25 pages, 3 figures, 3 table
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