382 research outputs found
The Large N Harmonic Oscillator as a String Theory
We propose a duality between the large-N gauged harmonic oscillator and a
novel string theory in two dimensions.Comment: 31 pages, 2 figures; v2: fixed typo
A toy model for the AdS/CFT correspondence
We study the large N gauged quantum mechanics for a single Hermitian matrix
in the Harmonic oscillator potential well as a toy model for the AdS/CFT
correspondence. We argue that the dual geometry should be a string in two
dimensions with a curvature of stringy size. Even though the dual geometry is
not weakly curved, one can still gain knowledge of the system from a detailed
study of the open-closed string duality. We give a mapping between the basis of
states made of traces (closed strings) and the eigenvalues of the matrix
(D-brane picture) in terms of Schur polynomials. We connect this model with the
study of giant gravitons in AdS_5 x S^5. We show that the two giant gravitons
that expand along AdS_5 and S^5 can be interpreted in the matrix model as
taking an eigenvalue from the Fermi sea and exciting it very much, or as making
a hole in the Fermi sea respectively. This is similar to recent studies of the
c=1 string. This connection gives new insight on how to perform calculations
for giant gravitons.Comment: 19 pages JHEP, 4 figures. v2: comments added, typos fixed, additional
refs. v3: The paper has been largely revised, to make the relation as a limit
of N=4 SYM clear, also some proofs have been written in full rather than
sketched. This updated version reflects the changes that were made in the
published versio
A Holographic View on Matrix Model of Black Hole
We investigate a deformed matrix model proposed by Kazakov et.al. in relation
to Witten's two-dimensional black hole. The existing conjectures assert the
equivalence of the two by mapping each to a deformed c=1 theory called the
sine-Liouville theory. We point out that the matrix theory in question may be
naturally interpreted as a gauged quantum mechanics deformed by insertion of an
exponentiated Wilson loop operator, which gives us more direct and holographic
map between the two sides. The matrix model in the usual scaling limit must
correspond to the bosonic SL(2,R)/U(1) theory in genus expansion but exact in
\alpha'. We successfully test this by computing the Wilson loop expectation
value and comparing it against the bulk computation. For the latter, we employ
the \alpha'-exact geometry proposed by Dijkgraaf, Verlinde, and Verlinde, which
was further advocated by Tseytlin. We close with comments on open problems.Comment: LaTeX, 19 page
On the S-matrix of Type 0 String Theory
The recent discovery of non-perturbatively stable two-dimensional string
backgrounds and their dual matrix models allows the study of complete
scattering matrices in string theory. In this note we adapt work of Moore,
Plesser, and Ramgoolam on the bosonic string to compute the exact S-matrices of
0A and 0B string theory in two dimensions. Unitarity of the 0B theory requires
the inclusion of massless soliton sectors carrying RR scalar charge as
asymptotic states. We propose a regularization of IR divergences and find
transition probabilities that distinguish the otherwise energetically
degenerate soliton sectors. Unstable D-branes can decay into distinct soliton
sectors.Comment: 30 pages, 6 figures, harvma
Tadpole Cancellation in Unoriented Liouville Theory
The tadpole cancellation in the unoriented Liouville theory is discussed.
Using two different methods -- the free field method and the boundary-crosscap
state method, we derive one-loop divergences. Both methods require two
D1-branes with the symplectic gauge group to cancel the orientifold tadpole
divergence. However, the finite part left is different in each method and this
difference is studied. We also discuss the validity of the free field method
and the possible applications of our result.Comment: 12 pages; v2: sign error in the crosscap state is corrected, some
related argumets are modified and clarified; v3: minor corrections;
v4:reference adde
The Cap in the Hat: Unoriented 2D Strings and Matrix(-Vector) Models
We classify the possible bosonic and Type 0 unoriented string theories in two
dimensions, and find their dual matrix(-vector) models. There are no RP^2 R-R
tadpoles in any of the models, but many of them possess a massless tachyon
tadpole. Thus all the models we find are consistent two-dimensional string
vacua, but some get quantum corrections to their classical tachyon background.
Where possible, we solve the tadpole cancellation condition, and find all the
tachyon tadpole-free theories.Comment: 34 pages, LaTeX; Errors corrected in some of the open string
representations in tables 1, 2 and 3. References and acknowledgments adde
Squashed Giants: Bound States of Giant Gravitons
We consider giant gravitons in the maximally supersymmetric type IIB
plane-wave, in the presence of a constant NSNS B-field background. We show that
in response to the background B-field the giant graviton would take the shape
of a deformed three-sphere, the size and shape of which depend on the B-field,
and that the giant becomes classically unstable once the B-field is larger than
a critical value B_{cr}. In particular, for the B-field which is
(anti-)self-dual under the SO(4) isometry of the original giant S^3, the closed
string metric is that of a round S^3, while the open string metric is a
squashed three-sphere. The squashed giant can be interpreted as a bound state
of a spherical three-brane and circular D-strings. We work out the spectrum of
geometric fluctuations of the squashed giant and study its stability. We also
comment on the gauge theory which lives on the brane (which is generically a
noncommutative theory) and a possible dual gauge theory description of the
deformed giant.Comment: Latex file, 32 pages, 6 .eps figures; v3: typos correcte
UV Finite Brane Decay
The decay of an unstable D-brane via closed string emission and open string
pair production is considered in subcritical string theory with a spacelike
linear dilaton. The decay rate is given by the imaginary part of the annulus,
which has ambiguities corresponding to the choices of incoming closed and open
string vacua. An exact expression for the full annulus diagram is computed with
a natural choice of incoming vacua. It is found that the ultraviolet
divergences present in critical string theory in both of these processes are
absent for any nonzero spacelike dilaton. Implications for the vexing issue of
the tachyon dust are discussed.Comment: 21 pages, 3 figures, minor changes, changed to JHEP styl
Non-Perturbative Effects in Matrix Models and D-branes
The large order growth of string perturbation theory in conformal
field theory coupled to world sheet gravity implies the presence of
non-perturbative effects, whose leading behavior can be
calculated in the matrix model approach. Recently it was proposed that the same
effects should be reproduced by studying certain localized D-branes in
Liouville Field Theory, which were constructed by A. and Al. Zamolodchikov. We
discuss this correspondence in a number of different cases: unitary minimal
models coupled to Liouville, where we compare the continuum analysis to the
matrix model results of Eynard and Zinn-Justin, and compact c=1 CFT coupled to
Liouville in the presence of a condensate of winding modes, where we derive the
matrix model prediction and compare it to Liouville theory. In both cases we
find agreement between the two approaches. The c=1 analysis also leads to
predictions about properties of D-branes localized in the vicinity of the tip
of the cigar in SL(2)/U(1) CFT with c=26.Comment: 27 pages, lanlmac; minor change
Evolution of Holographic Entanglement Entropy after Thermal and Electromagnetic Quenches
We study the evolution and scaling of the entanglement entropy after two
types of quenches for a 2+1 field theory, using holographic techniques. We
study a thermal quench, dual to the addition of a shell of uncharged matter to
four dimensional Anti-de Sitter (AdS_4) spacetime, and study the subsequent
formation of a Schwarzschild black hole. We also study an electromagnetic
quench, dual to the addition of a shell of charged sources to AdS_4, following
the subsequent formation of an extremal dyonic black hole. In these backgrounds
we consider the entanglement entropy of two types of geometries, the infinite
strip and the round disc, and find distinct behavior for each. Some of our
findings naturally supply results analogous to observations made in the
literature for lower dimensions, but we also uncover several new phenomena,
such as (in some cases) a discontinuity in the time derivative of the
entanglement entropy as it nears saturation, and for the electromagnetic
quench, a logarithmic growth in the entanglement entropy with time for both the
disc and strip, before settling to saturation.Comment: 30 pages, 19 figures. Corrected typos and added some discussion. To
appear in New J. Phy
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