395 research outputs found
Matrix Black Holes
Four and five dimensional extremal black holes with nonzero entropy have
simple presentations in M-theory as gravitational waves bound to configurations
of intersecting M-branes. We discuss realizations of these objects in matrix
models of M-theory, investigate the properties of zero-brane probes, and
propose a measure of their internal density. A scenario for black hole dynamics
is presented.Comment: 26 pages, harvmac; a few more references and additional comment
Annulus Amplitudes in the Minimal Superstring
We study the annulus amplitudes in the (2,4) minimal superstring theory using
the continuum worldsheet approach. Our results reproduce the semiclassical
behavior of the wavefunctions of FZZT-branes recently studied in hep-th/0412315
using the dual matrix model. We also study the multi-point functions of neutral
FZZT-branes and find the agreement between their semiclassical limit and the
worldsheet annulus calculation.Comment: 15 pages, lanlma
On the Boundary Dynamics of Chern-Simons Gravity
We study Chern-Simons theory with a complex G_C or a real G x G gauge group
on a manifold with boundary - this includes Lorentzian and Euclidean (anti-) de
Sitter (E/A)dS gravity for G=SU(2) or G=SL(2,R). We show that there is a
canonical choice of boundary conditions that leads to an unambiguous, fully
covariant and gauge invariant, off-shell derivation of the boundary action - a
G_C/G or G WZW model, coupled in a gauge invariant way to the boundary value of
the gauge field. In particular, for (E/A)dS gravity, the boundary action is a
WZW model with target space (E/A)dS_3, reminiscent of a worldsheet for
worldsheet mechanism. We discuss in some detail the properties of the boundary
theories that arise and we confront our results with various related
constructions in the literature.Comment: 22 pages, LaTeX2e, v2: JHEP3.cls, references and a footnote adde
Rolling Tachyons from Liouville theory
In this work we propose an exact solution of the c=1 Liouville model, i.e. of
the world-sheet theory that describes the homogeneous decay of a closed string
tachyon. Our expressions are obtained through careful extrapolation from the
correlators of Liouville theory with c > 25. In the c=1 limit, we find two
different theories which differ by the signature of Liouville field. The
Euclidean limit coincides with the interacting c=1 theory that was constructed
by Runkel and Watts as a limit of unitary minimal models. The couplings for the
Lorentzian limit are new. In contrast to the behavior at c > 1, amplitudes in
both c=1 models are non-analytic in the momenta and consequently they are not
related by Wick rotation.Comment: 22 page
A Note on c=1 Virasoro Boundary States and Asymmetric Shift Orbifolds
We comment on the conformal boundary states of the c=1 free boson theory on a
circle which do not preserve the U(1) symmetry. We construct these Virasoro
boundary states at a generic radius by a simple asymmetric shift orbifold
acting on the fundamental boundary states at the self-dual radius. We further
calculate the boundary entropy and find that the Virasoro boundary states at
irrational radius have infinite boundary entropy. The corresponding open string
description of the asymmetric orbifold is given using the quotient algebra
construction. Moreover, we find that the quotient algebra associated with a
non-fundamental boundary state contains the noncommutative Weyl algebra.Comment: 21 pages, harvmac; v2: minor clarification in section 3.4; v3: a
discussion on cocycles added in section 2, and low energy limit mistake
removed and clarifications added in section 4.
Noncritical String Correlators, Finite-N Matrix Models and the Vortex Condensate
We carry out a systematic study of correlation functions of momentum modes in
the Euclidean c=1 string, as a function of the radius and to all orders in
perturbation theory. We obtain simple explicit expressions for several classes
of correlators in terms of special functions. The Normal Matrix Model is found
to be a powerful calculational tool that computes c=1 string correlators even
at finite N. This enables us to obtain a simple combinatoric formula for the
2n-point function of unit momentum modes, which after T-duality determines the
vortex condensate. We comment on possible applications of our results to
T-duality at c=1 and to the 2d black hole/vortex condensate problem.Comment: 38 pages, LaTe
c=1 Matrix Models: Equivalences and Open-Closed String Duality
We give an explicit demonstration of the equivalence between the Normal
Matrix Model (NMM) of c=1 string theory at selfdual radius and the
Kontsevich-Penner (KP) model for the same string theory. We relate macroscopic
loop expectation values in the NMM to condensates of the closed string tachyon,
and discuss the implications for open-closed duality. As in c<1, the
Kontsevich-Miwa transform between the parameters of the two theories appears to
encode open-closed string duality, though our results also exhibit some
interesting differences with the c<1 case. We also briefly comment on two
different ways in which the Kontsevich model originates.Comment: 27 pages, latex, 1 figure, typos, discussion added, acknowledgements
update
Localized Tachyons and the g_cl conjecture
We consider C/Z_N and C^2/Z_N orbifolds of heterotic string theories and Z_N
orbifolds of AdS_3. We study theories with N=2 worldsheet superconformal
invariance and construct RG flows. Following Harvey, Kutasov, Martinec and
Moore, we compute g_cl and show that it decreases monotonically along RG flows-
as conjectured by them. For the heterotic string theories, the gauge degrees of
freedom do not contribute to the computation of g_cl.Comment: Corrections and clarifications made, 19 page
Semi-Classical Mechanics in Phase Space: The Quantum Target of Minimal Strings
The target space of minimal strings is embedded into the
phase space of an associated integrable classical mechanical model. This map is
derived from the matrix model representation of minimal strings. Quantum
effects on the target space are obtained from the semiclassical mechanics in
phase space as described by the Wigner function. In the classical limit the
target space is a fold catastrophe of the Wigner function that is smoothed out
by quantum effects. Double scaling limit is obtained by resolving the
singularity of the Wigner function. The quantization rules for backgrounds with
ZZ branes are also derived.Comment: 16 pages, 6 figure
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