70,545 research outputs found
From UV/IR mixing to closed strings
It was shown in hep-th/0301099 that the leading UV/IR mixing effects in
noncommutative gauge theories on D-branes are able to capture information about
the closed string spectrum of the parent string theory. The analysis was
carried out for D-branes on nonsupersymmetric C^3/Z_N orbifolds of Type IIB. In
this paper we consider D-branes on twisted circles compactifications of Type II
string theory. We find that the signs of the leading UV/IR mixing effects know
about the mass gap between the lowest modes in NSNS and RR closed string
towers. Moreover, the relevant piece of the field theory effective action can
be reproduced purely in the language of closed strings. Remarkably this
approach unifies in a single structure, that of a closed string exchange
between D-branes, both the leading planar and nonplanar effects associated to
the absence of supersymmetry.Comment: 28 pages, 4 figures, LaTex; v2 references added, misprints correcte
A Family of N=1 SU(N)^k Theories from Branes at Singularities
We obtain N=1 SU(N)^k gauge theories with bifundamental matter and a quartic
superpotential as the low energy theory on D3-branes at singular points. These
theories generalize that on D3-branes at a conifold point, studied recently by
Klebanov and Witten. For k=3 the defining equation of the singular point is
that of an isolated D_4 singularity. For k>3 we obtain a family of multimodular
singularities. The considered SU(N)^k theories flow in the infrared to a
non-trivial fixed point. We analyze the AdS/CFT correspondence for our
examples.Comment: 18 pages, 1 figure, TeX; v2 minor change
Argon ion pollution of the magnetosphere
Construction of a Solar Power Satellite (SPS) would require the injection of large quantities of propellant to transport material from Low Earth Orbit (LEO) to the construction site at Geostationary Earth Orbit (GEO). This injection, in the form of approx 10 to the 32nd power, 2 KeV argon ions (and associated electrons) per SPS, is comparable to the content of the plasmasphere (approx 10 to the 31st power ions). In addition to the mass deposited, this represents a considerable injection of energy. The injection is examined in terms of a simple model for the expansion of the beam plasma. General features of the subsequent magnetospheric convection of the argon are also examined
Topology and Strings: Topics in
A review on topological strings and the geometry of the space of two
dimensional theories. (Lectures given by C. Gomez at the Enrico Fermi Summer
School, Varenna, July 1994)Comment: 61 pages, late
A Note on the String Analog of Super-Symmetric Yang-Mills
A connection between the conifold locus of the type II string on the
Calabi-Yau manifold and the geometry of the quantum moduli of
super Yang-Mills is presented. This relation is obtained from
the anomalous behaviour of the super Yang-Mills special coordinates
under -duality transformation in .Comment: 7 pages, Late
APPLICATIONS OF DUALITY THEORY TO AGRICULTURE
Research Methods/ Statistical Methods,
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