14 research outputs found
Twistor Strings with Flavour
We explore the tree-level description of a class of N=2 UV-finite SYM
theories with fundamental flavour within a topological B-model twistor string
framework. In particular, we identify the twistor dual of the Sp(N) gauge
theory with one antisymmetric and four fundamental hypermultiplets, as well as
that of the SU(N) theory with 2N hypermultiplets. This is achieved by suitably
orientifolding/orbifolding the original N=4 setup of Witten and adding a
certain number of new topological 'flavour'-branes at the orientifold/orbifold
fixed planes to provide the fundamental matter. We further comment on the
appearance of these objects in the B-model on CP(3|4). An interesting aspect of
our construction is that, unlike the IIB description of these theories in terms
of D3 and D7-branes, on the twistor side part of the global flavour symmetry is
realised geometrically. We provide evidence for this correspondence by
calculating and matching amplitudes on both sides.Comment: 38+12 pages; uses axodraw.sty. v2: References added, minor
clarification
Integrable Spin Chains on the Conformal Moose
We consider N=1, D=4 superconformal U(N)^{pq} Yang-Mills theories dual to
AdS_5xS^5/Z_pxZ_q orbifolds. We construct the dilatation operator of this
superconformal gauge theory at one-loop planar level. We demonstrate that a
specific sector of this dilatation operator can be thought of as the transfer
matrix for a two-dimensional statistical mechanical system, related to an
integrable SU(3) anti-ferromagnetic spin chain system, which in turn is
equivalent to a 2+1-dimensional string theory where the spatial slices are
discretized on a triangular lattice. This is an extension of the SO(6) spin
chain picture of N=4 super Yang-Mills theory. We comment on the integrability
of this N=1 gauge theory and hence the corresponding three-dimensional
statistical mechanical system, its connection to three-dimensional lattice
gauge theories, extensions to six-dimensional string theories, AdS/CFT type
dualities and finally their construction via orbifolds and brane-box models. In
the process we discover a new class of almost-BPS BMN type operators with large
engineering dimensions but controllably small anomalous corrections.Comment: 53 pages, 14 eps figures; Added reference
A Relation Between Approaches to Integrability in Superconformal Yang-Mills Theory
We make contact between the infinite-dimensional non-local symmetry of the
typeIIB superstring on AdS5xS5 worldsheet theory and a non-abelian
infinite-dimensional symmetry algebra for the weakly coupled superconformal
gauge theory. We explain why the planar limit of the one-loop dilatation
operator is the Hamiltonian of a spin chain, and show that it commutes with the
g*2 N = 0 limit of the non-abelian charges.Comment: 19 pages, harvma
Classical Open String Integrability
We present a simple procedure to construct non-local conserved charges for
classical open strings on coset spaces. This is done by including suitable
reflection matrices on the classical transfer matrix. The reflection matrices
must obey certain conditions for the charges to be conserved and in involution.
We then study bosonic open strings on . We consider boundary
conditions corresponding to Giant Gravitons on ,
D5-branes and D7-branes. We find that we can construct the
conserved charges for the full bosonic string on a Maximal Giant Graviton or a
D7-brane. For the D5-brane, we find that this is possible only in a SU(2)
sub-sector of the open string. Moreover, the charges can not be constructed at
all for non-maximal Giant Gravitons. We discuss the interpretation of these
results in terms of the dual gauge theory spin chains.Comment: 23 pages, JHEP styl
The Similarity Hypothesis in General Relativity
Self-similar models are important in general relativity and other fundamental
theories. In this paper we shall discuss the ``similarity hypothesis'', which
asserts that under a variety of physical circumstances solutions of these
theories will naturally evolve to a self-similar form. We will find there is
good evidence for this in the context of both spatially homogenous and
inhomogeneous cosmological models, although in some cases the self-similar
model is only an intermediate attractor. There are also a wide variety of
situations, including critical pheneomena, in which spherically symmetric
models tend towards self-similarity. However, this does not happen in all cases
and it is it is important to understand the prerequisites for the conjecture.Comment: to be submitted to Gen. Rel. Gra
The statistics of string/M theory vacua
We discuss systematic approaches to the classification of string/M theory
vacua, and physical questions this might help us resolve. To this end, we
initiate the study of ensembles of effective Lagrangians, which can be used to
precisely study the predictive power of string theory, and in simple examples
can lead to universality results. Using these ideas, we outline an approach to
estimating the number of vacua of string/M theory which can realize the
Standard Model.Comment: harvmac, 72pp (v4: fixed error in discussion of quiver ensembles