5,372 research outputs found
On Exact Symmetries and Massless Vectors in Holographic Flows and other Flux Vacua
We analyze the isometries of Type IIB flux vacua based on the
Papadopolous-Tseytlin ansatz and identify the related massless bulk vector
fields. To this end we devise a general ansatz, valid in any flux
compactification, for the fluctuations of the metric and p-forms that
diagonalizes the coupled equations. We then illustrate the procedure in the
simple case of holographic flows driven by the RR 3-form flux only.
Specifically we study the fate of the isometries of the Maldacena-Nunez
solution associated to wrapped D5-branes.Comment: 23 page
From Correlators to Wilson Loops in Chern-Simons Matter Theories
We study n-point correlation functions for chiral primary operators in three
dimensional supersymmetric Chern-Simons matter theories. Our analysis is
carried on in N=2 superspace and covers N=2,3 supersymmetric CFT's, the N=6
ABJM and the N=8 BLG models. In the limit where the positions of adjacent
operators become light-like, we find that the one-loop n-point correlator
divided by its tree level expression coincides with a light-like n-polygon
Wilson loop. Remarkably, the result can be simply expressed as a linear
combination of five dimensional two-mass easy boxes. We manage to evaluate the
integrals analytically and find a vanishing result, in agreement with previous
findings for Wilson loops.Comment: 32 pages, 6 figures, JHEP
Precision Spectroscopy and Higher Spin symmetry in the ABJM model
We revisit Kaluza-Klein compactification of 11-d supergravity on S^7/Z_k
using group theory techniques that may find application in other flux vacua
with internal coset spaces. Among the SO(2) neutral states, we identify
marginal deformations and fields that couple to the recently discussed
world-sheet instanton of Type IIA on CP^3. We also discuss charged states, dual
to monopole operators, and the Z_k projection of the Osp(4|8) singleton and its
tensor products. In particular, we show that the doubleton spectrum may account
for N=6 higher spin symmetry enhancement in the limit of vanishing 't Hooft
coupling in the boundary Chern-Simons theory.Comment: 44 page
Consistency Conditions on S-Matrix of Spin 1 Massless Particles
Motivated by new techniques in the computation of scattering amplitudes of
massless particles in four dimensions, like BCFW recursion relations, the
question of how much structure of the S-matrix can be determined from purely
S-matrix arguments has received new attention. The BCFW recursion relations for
massless particles of spin 1 and 2 imply that the whole tree-level S-matrix can
be determined in terms of three-particle amplitudes (evaluated at complex
momenta). However, the known proofs of the validity of the relations rely on
the Lagrangian of the theory, either by using Feynman diagrams explicitly or by
studying the effective theory at large complex momenta. This means that a
purely S-matrix theoretic proof of the relations is still missing. The aim of
this paper is to provide such a proof for spin 1 particles by extending the
four-particle test introduced by P. Benincasa and F. Cachazo in
arXiv:0705.4305[hep-th] to all particles. We show how n-particle tests imply
that the rational function built from the BCFW recursion relations possesses
all the correct factorization channels including holomorphic and
anti-holomorphic collinear limits. This in turn implies that they give the
correct S-matrix of the theory.Comment: 24 pages, 4 figure
Pair Production of small Black Holes in Heterotic String Theories
We study pair production of small BPS BH's in heterotic strings compactified
on tori and in the FHSV model. After recalling the identification of small BH's
in the perturbative BPS spectrum, we compute the tree-level amplitudes for
processes initiated by massless vector bosons or gravitons. We then analyze the
resulting cross sections in terms of energy and angular distributions. Finally,
we briefly comment on scenari with large extra dimensions and on
generalizations of our results to non-BPS, non-extremal and rotating BH's.Comment: 33 page
From lightcone actions to maximally supersymmetric amplitudes
In this article actions for N=4 SYM and N=8 supergravity are formulated in
terms of a chiral superfield, which contains only the physical degrees of
freedom of either theory. In these new actions, which originate from the
lightcone superspace, the supergravity cubic vertex is the square of the gauge
theory one (omitting the color structures). Amplitude calculations using the
corresponding Feynman supergraph rules are tedious, but can be simplified by
choosing a preferred superframe. Recursive calculations of all MHV amplitudes
in N=4 SYM and the four-point N=8 supergravity amplitude are shown to agree
with the known results and connections to the BCFW recursion relations are
pointed out. Finally, the new path integrals are discussed in the context of
the double-copy property relating N=4 SYM theory to N=8 supergravity.Comment: 29 pages, 2 figures, v2: title modified, published versio
Self-duality of the D1-D5 near-horizon
We explore fermionic T-duality and self-duality in the geometry AdS3 x S3 x
T4 in type IIB supergravity. We explicitly construct the Killing spinors and
the fermionic T-duality isometries and show that the geometry is self-dual
under a combination of two bosonic AdS3 T-dualities, four fermionic T-dualities
and either two additional T-dualities along T4 or two T-dualities along S3. In
addition, we show that the presence of a B-field acts as an obstacle to
self-duality, a property attributable to S- duality and fermionic T-duality not
commuting. Finally, we argue that fermionic T-duality may be extended to CY2 =
K3, a setting where we cannot explicitly construct the Killing spinors.Comment: 24 pages, references added, changes made to reinforce the point that
S-duality and fermionic T-duality generically do not commute, version
accepted to JHE
Solution to the Ward Identities for Superamplitudes
Supersymmetry and R-symmetry Ward identities relate on-shell amplitudes in a
supersymmetric field theory. We solve these Ward identities for (Next-to)^K MHV
amplitudes of the maximally supersymmetric N=4 and N=8 theories. The resulting
superamplitude is written in a new, manifestly supersymmetric and R-invariant
form: it is expressed as a sum of very simple SUSY and SU(N)_R-invariant
Grassmann polynomials, each multiplied by a "basis amplitude". For (Next-to)^K
MHV n-point superamplitudes the number of basis amplitudes is equal to the
dimension of the irreducible representation of SU(n-4) corresponding to the
rectangular Young diagram with N columns and K rows. The linearly independent
amplitudes in this algebraic basis may still be functionally related by
permutation of momenta. We show how cyclic and reflection symmetries can be
used to obtain a smaller functional basis of color-ordered single-trace
amplitudes in N=4 gauge theory. We also analyze the more significant reduction
that occurs in N=8 supergravity because gravity amplitudes are not ordered. All
results are valid at both tree and loop level.Comment: 29 pages, published versio
Form factors of chiral primary operators at two loops in ABJ(M)
archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2013-34 slaccitation: %%CITATION = ARXIV:1305.2422;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2013-34 slaccitation: %%CITATION = ARXIV:1305.2422;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2013-34 slaccitation: %%CITATION = ARXIV:1305.2422;%
Running Scaling Dimensions in Holographic Renormalization Group Flows
Holographic renormalization group flows can be interpreted in terms of
effective field theory. Based on such an interpretation, a formula for the
running scaling dimensions of gauge-invariant operators along such flows is
proposed. The formula is checked for some simple examples from the AdS/CFT
correspondence, but can be applied also in non-AdS/non-CFT cases.Comment: 14 pages, 2 figure
- …