520 research outputs found
BRST Quantization of Noncommutative Gauge Theories
In this paper, the BRST symmetry transformation is presented for the
noncommutative U(N) gauge theory. The nilpotency of the charge associated to
this symmetry is then proved. As a consequence for the space-like
non-commutativity parameter, the Hilbert space of physical states is determined
by the cohomology space of the BRST operator as in the commutative case.
Further, the unitarity of the S-matrix elements projected onto the subspace of
physical states is deduced.Comment: 20 pages, LaTeX, no figures, one reference added, to appear in Phys.
Rev.
Planar and Nonplanar Konishi Anomalies and Effective Superpotential for Noncommutative N=1 Supersymmetric U(1)
The Konishi anomalies for noncommutative N=1 supersymmetric U(1) gauge theory
arising from planar and nonplanar diagrams are calculated. Whereas planar
Konishi anomaly is the expected \star-deformation of the commutative anomaly,
nonplanar anomaly reflects the important features of nonplanar diagrams of
noncommutative gauge theories, such as UV/IR mixing and the appearance of
nonlocal open Wilson lines. We use the planar and nonplanar Konishi anomalies
to calculate the effective superpotential of the theory. In the limit of
vanishing |\Theta p|, with \Theta the noncommutativity parameter, the
noncommutative effective superpotential depends on a gauge invariant
superfield, which includes supersymmetric Wilson lines, and has nontrivial
dependence on the gauge field supermultiplet.Comment: LaTeX, 36 pages. Version 2: Typos Corrected. Version 3: Extensively
revised version, 42 pages, to be published in Int. J. Mod. Phys. A. (2005
Density assessment of muddy shore crabs in the eastern part of Bandar Abbas
Crabs of intertidal zone of a muddy shore in Bandar Abbas were studied using monthly examination of Goharshad and Terminal stations during August 2005 to July 2006. Sampling was done by Corer and 14 species from 6 families were identified. Crabs were from Ocypodidae, Pinnotheridae, Pilumnidae, Trapeziidae, Leucosiidae and Varunidae families. Results showed Ocypodidae, the most abundant and diverse with 1196 individuals/m^2, was more abundant but less diverse in Goharshad station compared to Terminal which could be attributed to the urban pollution in Terminal station. Pinnotheridae with 64 individuals/m 2 showed an adaptation to organic materials but was not resistant to being out of water. Pilumnidae and Trapeziidae were found in small numbers in the stattions. Genus Ebalia from Leucosiidae with 27.18 individuals/m^2 showed positive reaction to organic materials and was resistant to being out of water. Varunidae were present with a few specimens probably because of human disturbance or speed in burrowing and escaping from sampling. Because civic pollution enter Terminal station, The results of this research showed that crabs react to urban pollution and hence are suitable as environmental indicators
Noncommutativity relations in type IIB theory and their supersymmetry
In the present paper we investigate noncommutativity of and -brane
world-volumes embedded in space-time of type IIB superstring theory. Boundary
conditions, which preserve half of the initial supersymmetry, are treated as
canonical constraints. Solving the constraints we obtain original coordinates
in terms of the effective coordinates and momenta. Presence of momenta induces
noncommutativity of string endpoints. We show that noncommutativity relations
are connected by N=1 supersymmetry transformations and noncommutativity
parameters are components of N=1 supermultiplet
Type I background fields in terms of type IIB ones
We choose such boundary conditions for open IIB superstring theory which
preserve N=1 SUSY. The explicite solution of the boundary conditions yields
effective theory which is symmetric under world-sheet parity transformation
. We recognize effective theory as closed type I
superstring theory. Its background fields,beside known even fields of
the initial IIB theory, contain improvements quadratic in odd ones.Comment: 4 revtex pages, no figure
Metal concentrations in razor clam Solen dactylus (Von Cosel, 1989) (Bivalvia: Solenidae), sediments and water in Golshahr coast of Bandar Abbas, Persian Gulf
In a complementary field study, the concentrations of some metals (Cu, Ag, Pb, Zn, Ni, Co, Mn, Fe, As, Cd, Cr, Mg and Ba) were measured in clam Solen dactylus, sediments and water collected at two stations (Park-e-Qadir, 56° 20/ E, 27° 11/ and Nakhl-e-Nakhoda, 56° 23/ E, 27° 10/ N) of Bandar Abbas coastal waters of the Persian Gulf in November 2008 and February 2009 showing different contamination levels. Although there is little information on metal concentrations in macro-benthic animals in this area, this study, for the first time, reports the accumulation of some metals in S. dactylus in order to introduce this species as a bioindicator for this area. Results indicated that Mg and Fe were the two most abundant metals in clams and sediments. The maximum and minimum metal concentrations in clams belonged to Mg (3850-5040 µgg-1 dry wt) and Ag (0.30-0.40-0.58 µgg-1 dry wt), respectively. There was a significant relationship between the accumulation of metals in clams, sediment and water samples. A significant relationship between clam lengths and concentrations of Cu (positive) and Mg (negative) were observed. Our study also showed that variable metal concentrations were related to different sampling stations, seasons and their interactions as well. Bioaccumulation of metals in clams was significantly different for eight metal elements between start of the gametogenesis and ripeness stages. Our investigation indicated that the clam S. dactylus could be a useful bioindicator for Zinc
On the Anomalies and Schwinger Terms in Noncommutative Gauge Theories
Invariant (nonplanar) anomaly of noncommutative QED is reexamined. It is
found that just as in ordinary gauge theory UV regularization is needed to
discover anomalies, in noncommutative case, in addition, an IR regularization
is also required to exhibit existence of invariant anomaly. Thus resolving the
controversy in the value of invariant anomaly, an expression for the
unintergrated anomaly is found. Schwinger terms of the current algebra of the
theory are derived.Comment: LaTeX, axodraw.sty, 1 figure; v2: Typos corrected, References added,
Version to appear in Int. J. Mod. Phys. A (2006
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