60 research outputs found
A Note on T-dualities in the Pure Spinor Heterotic String
In this note we study the preservation of the classical pure spinor BRST
constraints under super T-duality transformations. We also determine the
invariance of the one-loop conformal invariance and of the local gauge and
Lorentz anomalies under the super T-dualities.Comment: References adde
Reply to the comment by D. Kreimer and E. Mielke
We respond to the comment by Kreimer et. al. about the torsional contribution
to the chiral anomaly in curved spacetimes. We discuss their claims and refute
its main conclusion.Comment: 9 pages, revte
BRST Anomaly and Superspace Constraints of the Pure Spinor Heterotic String in a Curved Background
The pure spinor heterotic string in a generic super Yang-Mills and
supergravity background is considered. We determine the one-loop BRST anomaly
at the cohomological level. We prove that it can be absorbed by consistent
corrections of the classical constraints due to Berkovits and Howe, in
agreement with the Green-Schwarz cancelation mechanism.Comment: harvmac-big, 18 pages; references added; minor correction
A Note on the Classical BRST Symmetry of the Pure Spinor String in a Curved Background
The classical pure spinor version of the heterotic superstring in a
supergravity and super Yang-Mills background is considered. We obtain the BRST
transformations of the world-sheet fields. They are consistent with the
constraints obtained from the nilpotence of the BSRT charge and the
holomorphicity of the BRST current.Comment: References adde
Superspace formulations of ten-dimensional supergravity
We present a new formulation for N=1, D=10 supergravity in superspace, in
presence of a Lorentz Chern-Simons-form. This formulation entails the following
properties: it furnishes a solution of the Bianchi identities that is
algebraically consistent to all orders in alpha'; at first order it is the
simplest formulation proposed so far, and it is therefore most suitable for an
explicit higher order analysis; it allows a well defined perturbative expansion
in alpha', in which no poltergeist fields appear; it reconciles the two
different classes of first order solutions available in the literature, that
until now appeared physically inequivalent.Comment: 22 pages, no figures, references and comments adde
Geometry and stability of spinning branes in AdS gravity
The geometry of spinning codimension-two branes in AdS spacetime is analyzed
in three and higher dimensions. The construction of non-extremal solutions is
based on identifications in the covering of AdS space by isometries that have
fixed points. The discussion focuses on the cases where the parameters of
spinning states can be related to the velocity of a boosted static
codimension-two brane. The resulting configuration describes a single spinning
brane, or a set of intersecting branes, each one produced by an independent
identification. The nature of the singularity is also examined, establishing
that the AdS curvature acquires one in the form of a Dirac delta distribution.
The stability of the branes is studied in the framework of Chern-Simons AdS
supergravity. A class of branes, characterized by one free parameter, are shown
to be stable when the BPS conditions are satisfied. In 3D, these stable branes
are extremal, while in higher dimensions, the BPS branes are not the extremal
ones.Comment: 40 pages, 6 figure
Higher Dimensional Gravity, Propagating Torsion and AdS Gauge Invariance
The most general theory of gravity in d-dimensions which leads to second
order field equations for the metric has [(d-1)/2] free parameters. It is shown
that requiring the theory to have the maximum possible number of degrees of
freedom, fixes these parameters in terms of the gravitational and the
cosmological constants. In odd dimensions, the Lagrangian is a Chern-Simons
form for the (A)dS or Poincare groups. In even dimensions, the action has a
Born-Infeld-like form. Torsion may occur explicitly in the Lagrangian in the
parity-odd sector and the torsional pieces respect local (A)dS symmetry for
d=4k-1 only. These torsional Lagrangians are related to the Chern-Pontryagin
characters for the (A)dS group. The additional coefficients in front of these
new terms in the Lagrangian are shown to be quantized.Comment: 10 pages, two columns, no figures, title changed in journal, final
version to appear in Class. Quant. Gra
Torsion and the Gravity Dual of Parity Symmetry Breaking in AdS4/CFT3 Holography
We study four dimensional gravity with a negative cosmological constant
deformed by the Nieh-Yan torsional topological invariant with a
spacetime-dependent coefficient. We find an exact solution of the Euclidean
system, which we call the torsion vortex, having two asymptotic AdS4 regimes
supported by a pseudoscalar with a kink profile. We propose that the torsion
vortex is the holographic dual of a three dimensional system that exhibits
distinct parity breaking vacua. The torsion vortex represents a (holographic)
transition between these distinct vacua. We expect that from the boundary point
of view, the torsion vortex represents a `domain wall' between the two distinct
vacua.
From a bulk point of view, we point out an intriguing identification of the
parameters of the torsion vortex with those of an Abrikosov vortex in a Type I
superconductor. Following the analogy, we find that external Kalb-Ramond flux
then appears to support bubbles of flat spacetime within an asymptotically AdS
geometry.Comment: 26 pages, 4 figures; v2: minor improvements, references adde
Symmetries and observables in topological gravity
After a brief review of topological gravity, we present a superspace approach
to this theory. This formulation allows us to recover in a natural manner
various known results and to gain some insight into the precise relationship
between different approaches to topological gravity. Though the main focus of
our work is on the vielbein formalism, we also discuss the metric approach and
its relationship with the former formalism.Comment: 34 pages; a few explanations added in subsection 2.2.1, published
version of pape
Pure Spinor Formalism as an N=2 Topological String
Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are
added to the pure spinor formalism for the superstring. Twisted =3 N=2
generators are then constructed where the pure spinor BRST operator is the
fermionic spin-one generator, and the formalism is interpreted as a critical
topological string. Three applications of this topological string theory
include the super-Poincare covariant computation of multiloop superstring
amplitudes without picture-changing operators, the construction of a cubic open
superstring field theory without contact-term problems, and a new
four-dimensional version of the pure spinor formalism which computes F-terms in
the spacetime action.Comment: 34 pages harvmac te
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