79,769 research outputs found
Fully Localized Brane Intersections - The Plot Thickens
We study fully localized BPS brane solutions in classical supergravity using
a perturbative approach to the coupled Born-Infeld/bulk supergravity system. We
derive first order bulk supergravity fields for world-volume solitons
corresponding to intersecting M2-branes and to a fundamental string ending on a
D3-brane. One interesting feature is the appearance of certain off-diagonal
metric components and corresponding components of the gauge potentials. Making
use of a supersymmetric ansatz for the exact fields, we formulate a
perturbative expansion which applies to and
intersections. We find that perturbation theory
qualitatively distinguishes between certain of these cases: perturbation theory
breaks down at second order for intersecting M2-branes and D-branes with
while it is well behaved, at least to this order, for the remaining
cases. This indicates that the behavior of the full non-linear intersecting
Dp-brane solutions may be qualitatively different for than for , and that fully localized asymptotically flat solutions for may
not exist. We discuss the consistency of these results with world-volume field
theory properties.Comment: 27 pages, Plain Tex, 1 figure, added references, numerical factors
correcte
A Heterotic Multimonopole Solution
An exact multimonopole solution of heterotic string theory is presented. The
solution is constructed by a modification of the 't Hooft ansatz for a
four-dimensional instanton. An analogous solution in Yang-Mills field theory
saturates a Bogomoln'yi bound and possesses the topology and far field limit of
a multimonopole configuration, but has divergent action near each source. In
the string solution, however, the divergences from the Yang-Mills sector are
precisely cancelled by those from the gravity sector. The resultant action is
finite and easily computed. The Manton metric on moduli space for the
scattering of two string monopoles is found to be flat to leading order in the
impact parameter, in agreement with the trivial scattering predicted by a test
monopole calculation.Comment: 19 page
Pure spinors in AdS and Lie algebra cohomology
We show that the BRST cohomology of the massless sector of the Type IIB
superstring on AdS5xS5 can be described as the relative cohomology of an
infinite-dimensional Lie superalgebra. We explain how the vertex operators of
ghost number 1, which correspond to conserved currents, are described in this
language. We also give some algebraic description of the ghost number 2
vertices, which appears to be new. We use this algebraic description to clarify
the structure of the zero mode sector of the ghost number two states in flat
space, and initiate the study of the vertices of the higher ghost number.Comment: 39pp. LaTeX; v2: corrections in Section 4; v3: expanded Section 4.10,
added reference; v4: added example of a vertex at the ghost number 3 in
Section 5.3, removed Section 4.9, added explanations; v5: corrections in
Sections 3.3 and 4.
Algebras from Slightly Broken Higher Spin Symmetries
We define a class of -algebras that are obtained by deformations of
higher spin symmetries. While higher spin symmetries of a free CFT form an
associative algebra, the slightly broken higher spin symmetries give rise to a
minimal -algebra extending the associative one. These
-algebras are related to non-commutative deformation quantization
much as the unbroken higher spin symmetries result from the conventional
deformation quantization. In the case of three dimensions there is an
additional parameter that the -structure depends on, which is to be
related to the Chern-Simons level. The deformations corresponding to the
bosonic and fermionic matter lead to the same -algebra, thus
manifesting the three-dimensional bosonization conjecture. In all other cases
we consider, the -deformation is determined by a generalized free
field in one dimension lower.Comment: 48 pages, some pictures; typos fixed, presentation improve
Duality orbits of non-geometric fluxes
Compactifications in duality covariant constructions such as generalised
geometry and double field theory have proven to be suitable frameworks to
reproduce gauged supergravities containing non-geometric fluxes. However, it is
a priori unclear whether these approaches only provide a reformulation of old
results, or also contain new physics. To address this question, we classify the
T- and U-duality orbits of gaugings of (half-)maximal supergravities in
dimensions seven and higher. It turns out that all orbits have a geometric
supergravity origin in the maximal case, while there are non-geometric orbits
in the half-maximal case. We show how the latter are obtained from
compactifications of double field theory.Comment: 39 pages, 1 figure, 6 tables; v2: refs added, published versio
Fokker-Planck description of the transfer matrix limiting distribution in the scattering approach to quantum transport
The scattering approach to quantum transport through a disordered
quasi-one-dimensional conductor in the insulating regime is discussed in terms
of its transfer matrix \bbox{T}. A model of one-dimensional wires which
are coupled by random hopping matrix elements is compared with the transfer
matrix model of Mello and Tomsovic. We derive and discuss the complete
Fokker-Planck equation which describes the evolution of the probability
distribution of \bbox{TT}^{\dagger} with system length in the insulating
regime. It is demonstrated that the eigenvalues of \ln\bbox{TT}^{\dagger}
have a multivariate Gaussian limiting probability distribution. The parameters
of the distribution are expressed in terms of averages over the stationary
distribution of the eigenvectors of \bbox{TT}^{\dagger}. We compare the
general form of the limiting distribution with results of random matrix theory
and the Dorokhov-Mello-Pereyra-Kumar equation.Comment: 25 pages, revtex, no figure
Deep inelastic scattering structure functions of holographic spin-1 hadrons with
Two-point current correlation functions of the large limit of
supersymmetric and non-supersymmetric Yang-Mills theories at strong coupling
are investigated in terms of their string theory dual models with quenched
flavors. We consider non-Abelian global symmetry currents, which allow one to
investigate vector mesons with . From the correlation functions we
construct the deep inelastic scattering hadronic tensor of spin-one mesons,
obtaining the corresponding eight structure functions for polarized vector
mesons. We obtain several relations among the structure functions. Relations
among some of their moments are also derived. Aspects of the sub-leading
contributions in the and expansions are discussed. At leading
order we find a universal behavior of the hadronic structure functions.Comment: 48 pages, 8 figure
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