15 research outputs found
AdS and pp-wave D-particle superalgebras
We derive anticommutators of supercharges with a brane charge for a
D-particle in AdS(2) x S(2) and pp-wave backgrounds. A coset GL(2|2)/(GL(1))^4
and its Penrose limit are used with the supermatrix-valued coordinates for the
AdS and the pp-wave spaces respectively. The brane charges have position
dependence, and can be absorbed into bosonic generators by shift of momenta
which results in closure of the superalgebras.Comment: 15 page
On the spectrum of AdS/CFT beyond supergravity
We test the spectrum of string theory on AdS_5 x S^5 derived in
hep-th/0305052 against that of single-trace gauge invariant operators in free
N=4 super Yang-Mills theory. Masses of string excitations at critical tension
are derived by extrapolating plane-wave frequencies at g_{YM}=0 down to finite
J. On the SYM side, we present a systematic description of the spectrum of
single-trace operators and its reduction to PSU(2,2|4) superconformal primaries
via a refined Eratostenes' supersieve. We perform the comparison of the
resulting SYM/string spectra of charges and multiplicities order by order in
the conformal dimension \Delta up to \Delta=10 and find perfect agreement.
Interestingly, the SYM/string massive spectrum exhibits a hidden symmetry
structure larger than expected, with bosonic subgroup SO(10,2) and thirty-two
supercharges.Comment: 28 pages, LaTeX2
Loop Operators and the Kondo Problem
We analyse the renormalisation group flow for D-branes in WZW models from the
point of view of the boundary states. To this end we consider loop operators
that perturb the boundary states away from their ultraviolet fixed points, and
show how to regularise and renormalise them consistently with the global
symmetries of the problem. We pay particular attention to the chiral operators
that only depend on left-moving currents, and which are attractors of the
renormalisation group flow. We check (to lowest non-trivial order in the
coupling constant) that at their stable infrared fixed points these operators
measure quantum monodromies, in agreement with previous semiclassical studies.
Our results help clarify the general relationship between boundary transfer
matrices and defect lines, which parallels the relation between
(non-commutative) fields on (a stack of) D-branes and their push-forwards to
the target-space bulk.Comment: 22 pages, 2 figure
On T-Duality and Integrability for Strings on AdS Backgrounds
We discuss an interplay between T-duality and integrability for certain
classical non-linear sigma models. In particular, we consider strings on the
AdS_5 x S^5 background and perform T-duality along the four isometry directions
of AdS_5 in the Poincare patch. The T-dual of the AdS_5 sigma model is again a
sigma model on an AdS_5 space. This classical T-duality relation was used in
the recently uncovered connection between light-like Wilson loops and MHV gluon
scattering amplitudes in the strong coupling limit of the AdS/CFT duality. We
show that the explicit coordinate dependence along the T-duality directions of
the associated Lax connection (flat current) can be eliminated by means of a
field dependent gauge transformation. As a result, the gauge equivalent Lax
connection can easily be T-dualized, i.e. written in terms of the dual set of
isometric coordinates. The T-dual Lax connection can be used for the derivation
of infinitely many conserved charges in the T-dual model. Our construction
implies that local (Noether) charges of the original model are mapped to
non-local charges of the T-dual model and vice versa.Comment: 20 pages; v2: misprints corrected, references and minor
clarifications adde
Superstring in the plane-wave background with RR flux as a conformal field theory
We study the type IIB superstring in the plane-wave background with
Ramond-Ramond flux and formulate it as an exact conformal field theory in
operator formalism. One of the characteristic features of the superstring in a
consistent background with RR flux, such as the AdS5xS5 and its plane-wave
limit, is that the left- and the right-moving degrees of freedom on the
worldsheet are inherently coupled. In the plane-wave case, it is manifested in
the well-known fact that the Green-Schwarz formulation of the theory reduces to
that of free massive bosons and fermions in the light-cone gauge. This raises
the obvious question as to how this feature is reconciled with the underlying
conformal symmetry of the string theory. By adopting the semi-light-cone
conformal gauge, we will show that, despite the existence of such non-linear
left-right couplings, one can construct two independent sets of quantum
Virasoro operators in terms of fields obeying the free-field commutation
relations. Furthermore, we demonstrate that the BRST cohomology analysis
reproduces the physical spectrum obtained in the light-cone gauge.Comment: 37 pages, Latex, no figure; published versio