409 research outputs found
Chiral Symmetry Breaking in Brane Models
We discuss the chiral symmetry breaking in general intersecting Dq/Dp brane
models consisting of N_c Dq-branes and a single Dp-brane with an s-dimensional
intersection. There exists a QCD-like theory localized at the intersection and
the Dq/Dp model gives a holographic description of it. The rotational symmetry
of directions transverse to both of the Dq and Dp-branes can be identified with
a chiral symmetry, which is non-Abelian for certain cases. The asymptotic
distance between the Dq-branes and the Dp-brane corresponds to a quark mass. By
studying the probe Dp-brane dynamics in a Dq-brane background in the near
horizon and large N_c limit we find that the chiral symmetry is spontaneously
broken and there appear (pseudo-)Nambu-Goldstone bosons. We also discuss the
models at finite temperature.Comment: 29pages, 14figures. v2: a reference added. v3: 27pages, 12figures,
two references added, discussions on s=q configurations are corrected. v4:
minor change in Sec.
Super Weyl Anomalies in the AdS/CFT Correspondence
Anomalies of N = (4,4) superconformal field theories coupled to a conformal
supergravity background in two dimensions are computed by using the AdS/CFT
correspondence. We find that Weyl, axial gauge and super Weyl transformations
are anomalous, while general coordinate, local Lorentz, vector gauge and local
super transformations are not. The coefficients of the anomalies show that the
superconformal field theories have the central charge expected in the AdS/CFT
correspondence.Comment: 16 pages, LaTeX, references added and typos correcte
Supersymmetry in the AdS/CFT Correspondence
We study how local symmetry transformations of (p, q) anti de Sitter
supergravities in three dimensions act on fields on the two-dimensional
boundary. The boundary transformation laws are shown to be the same as those of
two-dimensional (p, q) conformal supergravities for p, q \leq 2. Weyl and super
Weyl transformations are generated from three-dimensional general coordinate
and super transformations.Comment: 11 pages, LaTe
Perturbations and Supersymmetries in AdS_3/CFT_2
Symmetry breaking by perturbations in the AdS/CFT correspondence is
discussed. Perturbations of vector fields to the AdS_3 x S^3 solution of the
six-dimensional N=(4,4) supergravity are considered. These perturbations are
identified as descendents of chiral primary operators of a two-dimensional
N=(4,4) CFT with conformal weight (2,2) or (1,1). We examine unbroken
symmetries by the perturbations in the CFT side as well as in the supergravity
side and find the same result: the N=(4,2) or N=(2,4) Poincare supersymmetry
for the (2,2) perturbation and the N=(0,4) or N=(4,0) superconformal symmetry
for the (1,1) perturbation.Comment: 23 pages, LaTeX, Minor change
One-dimensional Compression Tests of Sludge Cake from Dredged Sludge
One-dimensional compression tests were performed to investigate compression characteristics of sludge cake used as a construction material. The sludge cake is dewatering product of dredged sludge from the bottom of a lake. The test results show following compression characteristics. (1) For the undisturbed samples, e-log p curves show compressibility of overconsolidated clay ordinatily observed. (2) For the disturbed samples, there observed compressibility close to that of ordinary normally consolidated clay. (3) For the recompressed samples, there observed two turning points on e-log p curve. The compression presures(p(c1) and p(c2)) at those points for the unsubmerged tests have a linear correlation with the recompression pressure(p(s)). The submerged tests give very small values of p(c1) and p(c2) compared with the case of unsubmerged test. (4) For the recompressed samples, the first compression index(C(c1)) after p(c) has a linear correlation with the initial void ratio(e(0)), and the second compression index(C(c2)) shows almost constant value
Three-Form Flux with N=2 Supersymmetry on AdS_5 x S^5
In the context of the AdS/CFT correspondence the general form of a three-form
flux perturbation to the AdS_5 x S^5 solution in the type IIB supergravity
which preserves N=2 supersymmetry is obtained. The arbitrary holomorphic
function appearing in the N=1 case studied by Grana and Polchinski is
restricted to a quadratic function of the coordinates transverse to the
D3-branes.Comment: 11 pages, LaTe
The Simian Immunodeficiency Virus Targets Central Cell Cycle Functions through Transcriptional Repression In vivo
A massive and selective loss of CD4+ memory T cells occurs during the acute phase of immunodeficiency virus infections. The mechanism of this depletion is poorly understood but constitutes a key event with implications for progression. We assessed gene expression of purified T cells in Rhesus Macaques during acute SIVmac239 infection in order to define mechanisms of pathogenesis. We observe a general transcriptional program of over 1,600 interferon-stimulated genes induced in all T cells by the infection. Furthermore, we identify 113 transcriptional changes that are specific to virally infected cells. A striking downregulation of several key cell cycle regulator genes was observed and shared promotor-region E2F binding sites in downregulated genes suggested a targeted transcriptional control of an E2F regulated cell cycle program. In addition, the upregulation of the gene for the fundamental regulator of RNA polymerase II, TAF7, demonstrates that viral interference with the cell cycle and transcriptional regulation programs may be critical components during the establishment of a pathogenic infection in vivo
Chin-sternum-heart syndrome type of injury observed in a pedestrian victim of car traffic accident
Dominance of a single topological sector in gauge theory on non-commutative geometry
We demonstrate a striking effect of non-commutative (NC) geometry on
topological properties of gauge theory by Monte Carlo simulations. We study 2d
U(1) NC gauge theory for various boundary conditions using a new finite-matrix
formulation proposed recently. We find that a single topological sector
dictated by the boundary condition dominates in the continuum limit. This is in
sharp contrast to the results in commutative space-time based on lattice gauge
theory, where all topological sectors appear with certain weights in the
continuum limit. We discuss possible implications of this effect in the context
of string theory compactifications and in field theory contexts.Comment: 16 pages, 27 figures, typos correcte
- …