631 research outputs found
Holography in 4D (Super) Higher Spin Theories and a Test via Cubic Scalar Couplings
The correspondences proposed previously between higher spin gauge theories
and free singleton field theories were recently extended into a more complete
picture by Klebanov and Polyakov in the case of the minimal bosonic theory in
D=4 to include the strongly coupled fixed point of the 3d O(N) vector model.
Here we propose an N=1 supersymmetric version of this picture. We also
elaborate on the role of parity in constraining the bulk interactions, and in
distinguishing two minimal bosonic models obtained as two different consistent
truncations of the minimal N=1 model that retain the scalar or the
pseudo-scalar field. We refer to these models as the Type A and Type B models,
respectively, and conjecture that the latter is holographically dual to the 3d
Gross-Neveu model. In the case of the Type A model, we show the vanishing of
the three-scalar amplitude with regular boundary conditions. This agrees with
the O(N) vector model computation of Petkou, thereby providing a non-trivial
test of the Klebanov-Polyakov conjecture.Comment: 30p
Analysis of Higher Spin Field Equations in Four Dimensions
The minimal bosonic higher spin gauge theory in four dimensions contains
massless particles of spin s=0,2,4,.. that arise in the symmetric product of
two spin 0 singletons. It is based on an infinite dimensional extension of the
AdS_4 algebra a la Vasiliev. We derive an expansion scheme in which the
gravitational gauge fields are treated exactly and the gravitational curvatures
and the higher spin gauge fields as weak perturbations. We also give the
details of an explicit iteration procedure for obtaining the field equations to
arbitrary order in curvatures. In particular, we highlight the structure of all
the quadratic terms in the field equations.Comment: Latex, 30 pages, several clarifications and few references adde
On Critical Massive (Super)Gravity in adS3
We review the status of three-dimensional "general massive gravity" (GMG) in
its linearization about an anti-de Sitter (adS) vacuum, focusing on critical
points in parameter space that yield generalizations of "chiral gravity". We
then show how these results extend to N=1 super-GMG, expanded about a
supersymmetric adS vacuum, and also to the most general `curvature-squared' N=1
supergravity model.Comment: 10 pages, Proceedings of ERE 2010, Granada, 6-10 september 2010;
reference adde
Times Square in the Era of Post-truth Politics
In the era of ‘Post-truth politics’, political and activist
statements related to administration issues of different
regions on the Earth started to appear on the big digital
screens of Times Square, New York City. In this paper, we
investigate this phenomenon and focus in particular on the
role of the screens content (semantics) and the screens
material property (ie light) in conveying the message and
the construction of the notion of ‘reality’. Examples such as
‘Midnight moment’ and campaigns such as ‘Free
Balochistan’, ‘Call for Trump’s Impeachment’, ‘3
Billboards are explored and outline how billboards could be
used rather than an advertisement. Based on our
preliminary data collection and analysis of light
measurements in the Times Square, we found out that
during nighttime the square is occasionally brighter than
daytime and it seems that the intensity of light during
nighttime, contributes to the change of time perception
materially.
We suggest that the amount of nighttime illumination in
Times Square may contribute to the reconstructing the
notion of reality
Kundt spacetimes as solutions of topologically massive gravity
We obtain new solutions of topologically massive gravity. We find the general
Kundt solutions, which in three dimensions are spacetimes admitting an
expansion-free null geodesic congruence. The solutions are generically of
algebraic type II, but special cases are types III, N or D. Those of type D are
the known spacelike-squashed AdS_3 solutions, and of type N are the known AdS
pp-waves or new solutions. Those of types II and III are the first known
solutions of these algebraic types. We present explicitly the Kundt solutions
that are CSI spacetimes, for which all scalar polynomial curvature invariants
are constant, whereas for the general case we reduce the field equations to a
series of ordinary differential equations. The CSI solutions of types II and
III are deformations of spacelike-squashed AdS_3 and the round AdS_3,
respectively.Comment: 30 pages. This material has come from splitting v1 of arXiv:0906.3559
into 2 separate papers. v2: minor changes
Supersymmetric Higher Spin Theories
We revisit the higher spin extensions of the anti de Sitter algebra in four
dimensions that incorporate internal symmetries and admit representations that
contain fermions, classified long ago by Konstein and Vasiliev. We construct
the , Euclidean and Kleinian version of these algebras, as well as the
corresponding fully nonlinear Vasiliev type higher spin theories, in which the
reality conditions we impose on the master fields play a crucial role. The
supersymmetric higher spin theory in , on which we elaborate
further, is included in this class of models. A subset of Konstein-Vasiliev
algebras are the higher spin extensions of the superalgebras
for mod 4 and can be realized using
fermionic oscillators. We tensor the higher superalgebras of the latter kind
with appropriate internal symmetry groups and show that the mod 4
higher spin algebras are isomorphic to those with mod 4. We
describe the fully nonlinear higher spin theories based on these algebras as
well, and we elaborate further on the supersymmetric theory,
providing two equivalent descriptions one of which exhibits manifestly its
relation to the supersymmetric higher spin theory.Comment: 30 pages. Contribution to J. Phys. A special volume on "Higher Spin
Theories and AdS/CFT" edited by M. R. Gaberdiel and M. Vasilie
Structure and propertties of ball milled utrahigh-molecular weight Polyethylene - clay composite
In this work the composite material based on polymer matrix filled with clay is studied. The preparation of powder composition consists of mechanical activation of substances and further common ball milling of polymer and clay in a high energy planetary ball mill. The process is divided into two stages; the first stage involves crushing of clay to obtain a nanosized powder, and in the second stage preparation of powdered nanocomposite is carried out. New clay-polymer composite shows considerable increase in modulus of elasticity and a decrease in coefficient of friction
Higher Derivative Extension of 6D Chiral Gauged Supergravity
Six-dimensional (1,0) supersymmetric gauged Einstein-Maxwell supergravity is
extended by the inclusion of a supersymmetric Riemann tensor squared invariant.
Both the original model as well as the Riemann tensor squared invariant are
formulated off-shell and consequently the total action is off-shell invariant
without modification of the supersymmetry transformation rules. In this
formulation, superconformal techniques, in which the dilaton Weyl multiplet
plays a crucial role, are used. It is found that the gauging of the U(1)
R-symmetry in the presence of the higher-order derivative terms does not modify
the positive exponential in the dilaton potential. Moreover, the supersymmetric
Minkowski(4) x S^2 compactification of the original model, without the
higher-order derivatives, is remarkably left intact. It is shown that the model
also admits non-supersymmetric vacuum solutions that are direct product spaces
involving de Sitter spacetimes and negative curvature internal spaces.Comment: 32 pages; typos corrected, footnote in conclusions section adde
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