858 research outputs found
Branes at Generalized Conifolds and Toric Geometry
We use toric geometry to investigate the recently proposed relation between a
set of D3 branes at a generalized conifold singularity and type IIA
configurations of D4 branes stretched between a number of relatively rotated
NS5 branes. In particular we investigate how various resolutions of the
singularity corresponds to moving the NS branes and how Seiberg's duality is
realized when two relatively rotated NS-branes are interchanged.Comment: 19 pages, 8 figures; v2: references added, clarifying footnote on
Seiberg's duality adde
Naturalness and Chaotic Inflation in Supergravity from Massive Vector Multiplets
We study the embedding of the quadratic model of chaotic inflation into the
4D, N=1 minimal theories of supergravity by the use of massive vector
multiplets and investigate its robustness against higher order corrections. In
particular, we investigate the criterion of technical naturalness for the
inflaton potential. In the framework of the new-minimal formulation the massive
vector multiplet is built in terms of a real linear multiplet coupled to a
vector multiplet via the 4D analog of the Green-Schwarz term. This theory gives
rise to a single-field quadratic model of chaotic inflation, which is protected
by an shift symmetry which naturally suppresses the higher order corrections.
The embedding in the old-minimal formulation is again achieved in terms of a
massive vector multiplet and also gives rise to single-field inflation.
Nevertheless in this case there is no obvious symmetry to protect the model
from higher order corrections.Comment: 15 pages, version accepted in JHE
Constraints on Higher Derivative Operators in Maximally Supersymmetric Gauge Theory
Following the work of Dine and Seiberg for SU(2), we study the leading
irrelevant operators on the moduli space of N=4 supersymmetric SU(N) gauge
theory. These operators are argued to be one-loop exact, and are explicitly
computed.Comment: 6 pages, harvmac. Note added. (Only a subset of the leading
irrelevant operators have been shown to be one-loop exact.
Charged black holes in compactified spacetimes
We construct and investigate a compactified version of the four-dimensional
Reissner-Nordstrom-NUT solution, generalizing the compactified Schwarzschild
black hole that has been previously studied by several workers. Our approach to
compactification is based on dimensional reduction with respect to the
stationary Killing vector, resulting in three-dimensional gravity coupled to a
nonlinear sigma model. Using that the original non-compactified solution
corresponds to a target space geodesic, the problem can be linearized much in
the same way as in the case of no electric nor NUT charge. An interesting
feature of the solution family is that for nonzero electric charge but
vanishing NUT charge, the solution has a curvature singularity on a torus that
surrounds the event horizon, but this singularity is removed when the NUT
charge is switched on. We also treat the Schwarzschild case in a more complete
way than has been done previously. In particular, the asymptotic solution (the
Levi-Civita solution with the height coordinate made periodic) has to our
knowledge only been calculated up to a determination of the mass parameter. The
periodic Levi-Civita solution contains three essential parameters, however, and
the remaining two are explicitly calculated here.Comment: 20 pages, 3 figures. v2: Typo corrected, reference adde
Hyperkahler quotients and algebraic curves
We develop a graphical representation of polynomial invariants of unitary
gauge groups, and use it to find the algebraic curve corresponding to a
hyperkahler quotient of a linear space. We apply this method to four
dimensional ALE spaces, and for the A_k, D_k, and E_6 cases, derive the
explicit relation between the deformations of the curves away from the orbifold
limit and the Fayet-Iliopoulos parameters in the corresponding quotient
construction. We work out the orbifold limit of E_7, E_8, and some higher
dimensional examples.Comment: Two typos corrected--Journal version; 23 pages, 13 figures, harvma
Superspace Higher Derivative Terms in Two Dimensions
We study and supersymmetric theories with superspace higher
derivatives in two dimensions. A characteristic feature of these models is that
they have several different vacua, some of which break supersymmetry. Depending
on the vacuum, the equations of motion describe different propagating degrees
of freedom. Various examples are presented which illustrate their generic
properties. As a by-product we see that these new vacua give a dynamical way of
generating non-linear realizations. In particular, our 2D example is
the dimensional reduction of a 4D model, and gives a new way for the
spontaneous breaking of extended supersymmetry.Comment: 23 pages, v3: comments added, published versio
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