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.

Estimation growth parameters of Parastromateus niger in the coastal waters of Sistan and Baluchestan, Oman Sea

Using length frequency information collected for Parastromateus niger catch in the coastal waters of Sistan and Baluchestan, Oman Sea, we estimated growth parameters of the fish. The data were collected of the fork length of around 887 fish each month during 2001. The length infinity (L∞), growth coefficient (K) and the length at age zero (t0) of the fish measured as 57.8 cm, 0.3 per year and -0.003 respectively. The relationship between the length and weight of the fish was estimated as 0.0469 for “a” , 2.829 for "b" and 0.914 for the correlation coefficient. The average length of the fish in different months of the year calculated and a Tukey test showed that this was significantly different

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

On gravitational couplings in D-brane action

We compute the two closed string graviton - two open string scalar scattering amplitude on the disc to show that there is no second-derivative curvature - scalar coupling term R X^2 in the low-energy effective action of a D-brane in curved space in type II superstring theory.Comment: 15 pages, 1 figure, LaTex JHEP style; v2: reference added, typos corrected; v3: section 2 rewritten due to an error in gauge fixing, appendix added, conclusions unchange

Acute pouchitis: the condition that time forgot about

The ileoanal pouch offers patients with medically refractory ulcerative colitis the opportunity to avoid a permanent ostomy and utilize their own bowel as a reservoir allowing a more ‘natural defaecation’. However, medical complications from inflammatory (pouchitis, pre-pouch ileitis and cuffitis) and non-inflammatory (irritable pouch syndrome) are common and negatively impact the quality of life (QoL)

Canonical Quantization of Open String and Noncommutative Geometry

We perform canonical quantization of open strings in the $D$-brane background with a $B$-field. Treating the mixed boundary condition as a primary constraint, we get a set of secondary constraints. Then these constraints are shown to be equivalent to orbifold conditions to be imposed on normal string modes. These orbifold conditions are a generalization of the familiar orbifold conditions which arise when we describe open strings in terms of closed strings. Solving the constraints explicitly, we obtain a simple Hamiltonian for the open string, which reveals the nature of noncommutativity transparently.Comment: 14 pages, RevTex, added reference

Stretched Strings in Noncommutative Field Theory

Motivated by recent discussions of IR/UV mixing in noncommutative field theories, we perform a detailed analysis of the non-planar amplitudes of the bosonic open string in the presence of an external B-field at the one-loop level. We carefully isolate, at the string theory level, the contribution which is responsible for the IR/UV behavior in the field theory limit. We show that it is a pure open string effect by deriving it from the factorization of the one-loop amplitude into the disk amplitudes of intermediate open string insertions. We suggest that it is natural to understand IR/UV mixing as the creation of intermediate ``stretched strings''.Comment: 20 pages AMSLaTeX using JHEP.cls, 6 eps figures. Typos corrected and references adde

Twisted Bundles on Noncommutative T4T^4 and D-brane Bound States

We construct twisted quantum bundles and adjoint sections on noncommutative $T^4$, and investigate relevant D-brane bound states with non-Abelian backgrounds. We also show that the noncommutative $T^4$ with non-Abelian backgrounds exhibits SO$(4,4|Z)$ duality and via this duality we get a Morita equivalent $T^4$ on which only D0-branes exist. For a reducible non-Abelian background, the moduli space of D-brane bound states in Type II string theory takes the form $\prod_a (T^4)^{q_a}/S_{q_a}$.Comment: 19 pages, Latex. v2: Title is changed. Minor corrections. A reference adde

Worldvolume Uncertainty Relations for D-Branes

By quantizing an open string ending on a D-brane in a nontrivial supergravity background, we argue that there is a new kind of uncertainty relation on a D-brane worldvolume. Furthermore, we fix the form of the uncertainty relations and their dependence on the string coupling constant by requiring them to be consistent with various string theory and M theory dualities. In this way we find a web of uncertainties of spacetime for all kinds of brane probes, including fundamental strings, D-branes of all dimensions as well as M theory membranes and fivebranes.Comment: 19 pages, minor modification on p.