67 research outputs found
Small Black Holes and Superconformal Quantum Mechanics
Recently, Gaiotto, Strominger and Yin have proposed a holographic
representation of the microstates of certain N=2 black holes as chiral
primaries of a superconformal quantum mechanics living on D0-branes in the
attractor geometry. We show that their proposal can be succesfully applied to
`small' black holes which are dual to Dabholkar-Harvey states and have
vanishing horizon area in the leading supergravity approximation. This note is
a summary of hep-th/0505176 with S. Kim.Comment: 4 pages, to appear in the proceeding of PASCOS 2005, Gyeongju, Korea,
May 30-June 4, 200
Ghost Sector of Vacuum String Field Theory and the Projection Equation
We study the ghost sector of vacuum string field theory where the BRST
operator Q is given by the midpoint insertion proposed by Gaiotto, Rastelli,
Sen and Zwiebach. We introduce a convenient basis of half-string modes in terms
of which Q takes a particularly simple form. We show that there exists a field
redefinition which reduces the ghost sector field equation to a pure projection
equation for string fields satisfying the constraint that the ghost number is
equally divided over the left- and right halves of the string. When this
constraint is imposed, vacuum string field theory can be reformulated as a
cubic matrix model. Ghost sector solutions can be constructed from
projection operators on half-string Hilbert space just as in the matter sector.
We construct the ghost sector equivalent of various well-known matter sector
projectors such as the sliver, butterfly and nothing states.Comment: 25 pages, no figures. Typos corrected, published versio
The large N limit of C/Z_N and supergravity
The C/Z_N orbifold of type II string theory has localized tachyons with m^2
ranging from -1+1/N to -2/N in units of 2/\alpha'. We show that by restricting
attention to the lightest tachyons it is possible to take a zero-slope limit
where N is taken to infinity while N\alpha' is held fixed. This is done by
applying Buscher duality in the angular direction of the cone to obtain a
supergravity solution on which the tachyons are gravitational instabilities. In
this picture, supergravity provides a natural off-shell description of the
tachyonic interactions. For example, the three-point couplings can be read off
easily (to leading order in 1/N) from the supergravity action, and are in
agreement with the on-shell couplings computed using CFT techniques.Comment: 17 pages, 1 figure; v2: reference adde
Quantization of conical spaces in 3D gravity
We discuss the quantization and holographic aspects of a class of conical
spaces in 2+1 dimensional pure AdS gravity. These appear as topological
solitons in the Chern-Simons formulation of the theory and are closely related
to the recently studied conical solutions in higher spin gravity. We discuss
the classical fluctuations around these solutions, which form exceptional
coadjoint orbits of the asymptotic Virasoro group. We argue that the
quantization of these solutions leads to nonunitary representations of the
Virasoro algebra, on account of their having boundary graviton fluctuations
which lower the energy. We propose a framework to quantize them in a
semiclassical expansion in the inverse central charge, which we use to compute
their one-loop corrected energies. Interestingly, the resulting Virasoro
representations contain a null vector, thus providing an appearance of Kac's
degenerate representations, which are nonunitary at large central charge, in
the context of gravity. We match the computed quantum corrections in the bulk
with the properties of a class of primaries in Kac's classification.Comment: 26 pages. V2: minor changes; references and calculational details
adde
Level Four Approximation to the Tachyon Potential in Superstring Field Theory
We compute the tachyon potential to level 4 in NS superstring field theory.
We obtain 89% of the conjectured vacuum energy.Comment: Latex, 8 pages, 1 figure, published version, references change
The Tachyon Potential in Witten's Superstring Field Theory
We study the tachyon potential in the NS sector of Witten's cubic superstring
field theory. In this theory, the pure tachyon contribution to the potential
has no minimum. We find that this remains the case when higher modes up to
level two are included.Comment: Latex, 10 pages, 1 figure, published version, comments added
regarding the absence of the twist-invariance and the singular behaviour of
the potentia
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