3,183 research outputs found
Classification of IIB backgrounds with 28 supersymmetries
We show that all IIB backgrounds with strictly 28 supersymmetries are locally
isometric to the plane wave solution of arXiv:hep-th/0206195. Moreover, we
demonstrate that all solutions with more than 26 supersymmetries and only
5-form flux are maximally supersymmetric. The N=28 plane wave solution is a
superposition of the maximally supersymmetric IIB plane wave with a heterotic
string solution. We investigate the propagation of strings in this background,
find the spectrum and give the string light-cone Hamiltonian.Comment: 30 pages, typos correcte
Type IIB tensionless superstrings in a pp-wave background
We solve the tensionless string in a constant plane wave background and
obtain a hugely degenerate spectrum. This is the case for a large class of
plane wave backgrounds. We show that the solution can also be derived as a
consistent limit of the quantized tensile theory of IIB strings in a pp-wave.
This is in contrast to the situation for several other backgrounds.Comment: 1+17 pages, LaTeX, minor corrections, added new reference
Penrose Limits and RG Flows
The Penrose-Gueven limit simplifies a given supergravity solution into a
pp-wave background. Aiming at clarifying its relation to renormalization group
flow we study the Penrose-Guven limit of supergravity backgrounds that are dual
to non-conformal gauge theories. The resulting backgrounds fall in a class
simple enough that the quantum particle is exactly solvable. We propose a map
between the effective time-dependent quantum mechanical problem and the RG flow
in the gauge theory. As a testing ground we consider explicitly two Penrose
limits of the infrared fixed point of the Pilch-Warner solution. We analyze the
corresponding gauge theory picture and write down the operators which are the
duals of the low lying string states. We also address RG flows of a different
nature by considering the Penrose-Gueven limit of a stack of N D_p branes. We
note that in the far IR (for p<3)the limit generically has negative
mass-squared. This phenomenon signals, in the world sheet picture, the
necessity to transform to another description. In this regard, we consider
explicitly the cases of M2 from D2 and F1 from D1 .Comment: 35 pp, 6 figure
IIB solutions with N>28 Killing spinors are maximally supersymmetric
We show that all IIB supergravity backgrounds which admit more than 28
Killing spinors are maximally supersymmetric. In particular, we find that for
all N>28 backgrounds the supercovariant curvature vanishes, and that the
quotients of maximally supersymmetric backgrounds either preserve all 32 or
N<29 supersymmetries.Comment: 27 page
pp-waves in 11-dimensions with extra supersymmetry
The Killing spinor equations for pp-wave solutions of eleven dimensional
supergravity are analysed and it is shown that there are solutions that
preserve 18,20,22 and 24 supersymmetries, in addition to the generic solution
preserving 16 supersymmetries and the Kowalski-Glikman solution preserving 32
supersymmetries.Comment: 13 pages. Reference added, typos corrected, new examples of
7-parameter case presente
Penrose Limits, the Colliding Plane Wave Problem and the Classical String Backgrounds
We show how the Szekeres form of the line element is naturally adapted to
study Penrose limits in classical string backgrounds. Relating the "old"
colliding wave problem to the Penrose limiting procedure as employed in string
theory we discuss how two orthogonal Penrose limits uniquely determine the
underlying target space when certain symmetry is imposed. We construct a
conformally deformed background with two distinct, yet exactly solvable in
terms of the string theory on R-R backgrounds, Penrose limits. Exploiting
further the similarities between the two problems we find that the Penrose
limit of the gauged WZW Nappi-Witten universe is itself a gauged WZW plane wave
solution of Sfetsos and Tseytlin. Finally, we discuss some issues related to
singularity, show the existence of a large class of non-Hausdorff solutions
with Killing Cauchy Horizons and indicate a possible resolution of the problem
of the definition of quantum vacuum in string theory on these time-dependent
backgrounds.Comment: Some misprints corrected. Matches the version in print. To appear in
Classical & Quantum Gravit
Marginal deformation of N=4 SYM and Penrose limits with continuum spectrum
We study the Penrose limit about a null geodesic with 3 equal angular momenta
in the recently obtained type IIB solution dual to an exactly marginal
-deformation of N=4 SYM. The resulting background has non-trivial NS
3-form flux as well as RR 5- and 3-form fluxes. We quantise the light-cone
Green-Schwarz action and show that it exhibits a continuum spectrum. We show
that this is related to the dynamics of a charged particle moving in a Landau
plane with an extra interaction induced by the deformation. We interpret the
results in the dual N=1 SCFT.Comment: 26 pages, 2 figures; v2: typos corrected, field theory interpretation
extende
Decay Modes of Unstable Strings in Plane-Wave String Field Theory
The cubic interaction vertex of light-cone string field theory in the
plane-wave background has a simple effective form when considering states with
only bosonic excitations. This simple effective interaction vertex is used in
this paper to calculate the three string interaction matrix elements for states
of arbitrary bosonic excitation and these results are used to examine certain
decay modes on the mass-shell. It is shown that the matrix elements of one
string to two string decays involving only bosonic excitations will vanish to
all orders in 1/mu on the mass-shell when the number of excitations on the
initial string is less than or equal to two, but in general will not vanish
when the number of excitations is greater than two. Also, a truncated
calculation of the mass-shell matrix elements for one string to three string
decays of two excitation states is performed and suggests that these matrix
elements do not vanish on the mass-shell. There is, however, a quantitative
discrepancy between this last result and its (also non-vanishing) gauge theory
prediction from the BMN correspondence.Comment: 11 pages; v2: references added; v3: normalization of interaction
vertex and corresponding amplitudes changed by a factor of mu to reflect SFT
normalization (must now divide by mu to compare with BMN dual gauge theory),
and minor errors correcte
The Penrose limit of AdS*S space and holography
In the Penrose limit, AdS*S space turns into a Cahen-Wallach (CW) space whose
Killing vectors satisfy a Heisenberg algebra. This algebra is mapped onto the
holographic screen on the boundary of AdS. I show that the Heisenberg algebra
on the boundary of AdS may be obtained directly from the CW space by
appropriately constraining the states defined on it. The transformations
generated by the constraint are similar to gauge transformations. The
``holographic screen'' on the CW space is thus obtained as a ``gauge-fixing''
condition.Comment: 12 pages, improved discussion, to appear in Mod. Phys. Lett.
D-branes in PP-Waves and Massive Theories on Worldsheet with Boundary
We investigate the supersymmetric D-brane configurations in the pp-wave
backgrounds proposed by Maldacena and Maoz. We study the surviving
supersymmetry in a D-brane configuration from the worldvolume point of view.
When we restrict ourselves to the background with N=(2,2) supersymmetry and no
holomorphic Killing vector term, there are two types of supersymmetric
D-branes: A-type and B-type. An A-type brane is wrapped on a special Lagrangian
submanifold, and the imaginary part of the superpotential should be constant on
its worldvolume. On the other hand, a B-type brane is wrapped on a complex
submanifold, and the superpotential should be constant on its worldvolume. The
results are almost consistent with the worldsheet theory in the lightcone
gauge. The inclusion of gauge fields is also discussed and found BPS D-branes
with the gauge field excitations. Furthermore, we consider the backgrounds with
holomorphic Killing vector terms and N=(1,1) supersymmetric backgrounds.Comment: 27 pages, LaTeX, no figure. v2: typos corrected, comments added,
references added. v3: typos corrected, comments added, references added.
v4:typos correcte
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