968 research outputs found
Simplifying and Extending the AdS_5xS^5 Pure Spinor Formalism
Although the AdS_5xS^5 worldsheet action is not quadratic, some features of
the pure spinor formalism are simpler in an AdS_5xS^5 background than in a flat
background. The BRST operator acts geometrically, the left and right-moving
pure spinor ghosts can be treated as complex conjugates, the zero mode measure
factor is trivial, and the b ghost does not require non-minimal fields.
Furthermore, a topological version of the AdS_5xS^5 action with the same
worldsheet variables and BRST operator can be constructed by gauge-fixing a G/G
principal chiral model where G=PSU(2,2|4). This topological model is argued to
describe the zero radius limit that is dual to free N=4 super-Yang-Mills and
can also be interpreted as an "unbroken phase" of superstring theory.Comment: 39 pages harvma
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
One Loop Conformal Invariance of the Superstring in an AdS_5 x S^5 Background
It is proven that the pure spinor superstring in an AdS_5 x S^5 background
remains conformally invariant at one loop level in the sigma model perturbation
theory.Comment: 14 pages harvma
Flat Currents in the Classical AdS_5 x S^5 Pure Spinor Superstring
It is proven that the classical pure spinor superstring in an AdS_5 x S^5
background has a flat current depending on a continuous parameter. This
generalizes the recent result of Bena, et al. for the classical Green-Schwarz
superstring.Comment: 10 pages, 1 figure, harvma
Yang-Mills Action from Open Superstring Field Theory
We calculate the effective action for nonabelian gauge bosons up to quartic
order using WZW-like open superstring field theory. After including level zero
and level one contributions, we obtain with 75% accuracy the Yang-Mills quartic
term. We then prove that the complete effective action reproduces the exact
Yang-Mills quartic term by analytically performing a summation over the
intermediate massive states.Comment: 10 page
Relating Green-Schwarz and Extended Pure Spinor Formalisms by Similarity Transformation
In order to gain deeper understanding of pure-spinor-based formalisms of
superstring, an explicit similarity transformation is constructed which
provides operator mapping between the light-cone Green-Schwarz (LCGS) formalism
and the extended pure spinor (EPS) formalism, a recently proposed
generalization of the Berkovits' formalism in an enlarged space. By applying a
systematic procedure developed in our previous work, we first construct an
analogous mapping in the bosonic string relating the BRST and the light-cone
formulations. This provides sufficient insights and allows us to construct the
desired mapping in the more intricate case of superstring as well. The success
of the construction owes much to the enlarged field space where pure spinor
constraints are removed and to the existence of the ``B-ghost'' in the EPS
formalism.Comment: 37pages, no figur
A New First Class Algebra, Homological Perturbation and Extension of Pure Spinor Formalism for Superstring
Based on a novel first class algebra, we develop an extension of the pure
spinor (PS) formalism of Berkovits, in which the PS constraints are removed. By
using the homological perturbation theory in an essential way, the BRST-like
charge of the conventional PS formalism is promoted to a bona fide
nilpotent charge , the cohomology of which is equivalent to the
constrained cohomology of . This construction requires only a minimum number
(five) of additional fermionic ghost-antighost pairs and the vertex operators
for the massless modes of open string are obtained in a systematic way.
Furthermore, we present a simple composite "-ghost" field which
realizes the important relation , with the
Virasoro operator, and apply it to facilitate the construction of the
integrated vertex. The present formalism utilizes U(5) parametrization and the
manifest Lorentz covariance is yet to be achieved.Comment: 38 pages, no figure. Proof of triviality of delta-homology improved
and a reference adde
BRST quantization of the pure spinor superstring
We present a derivation of the scattering amplitude prescription for the pure
spinor superstring from first principles, both in the minimal and non-minimal
formulations, and show that they are equivalent. This is achieved by first
coupling the worldsheet action to topological gravity and then proceeding to
BRST quantize this system. Our analysis includes the introduction of constant
ghosts and associated auxiliary fields needed to gauge fix symmetries
associated with zero modes. All fields introduced in the process of
quantization can be integrated out explicitly, resulting in the prescriptions
for computing scattering amplitudes that have appeared previously in the
literature. The zero mode insertions in the path integral follow from the
integration over the constant auxiliary fields.Comment: 31 page
N=2 Sigma Models for Ramond-Ramond Backgrounds
Using the U(4) hybrid formalism, manifestly N=(2,2) worldsheet supersymmetric
sigma models are constructed for the Type IIB superstring in Ramond-Ramond
backgrounds. The Kahler potential in these N=2 sigma models depends on four
chiral and antichiral bosonic superfields and two chiral and antichiral
fermionic superfields. When the Kahler potential is quadratic, the model is a
free conformal field theory which describes a flat ten-dimensional target space
with Ramond-Ramond flux and non-constant dilaton. For more general Kahler
potentials, the model describes curved target spaces with Ramond-Ramond flux
that are not plane-wave backgrounds. Ricci-flatness of the Kahler metric
implies the on-shell conditions for the background up to the usual four-loop
conformal anomaly.Comment: 19 pages harvma
Ghost constraints and the covariant quantization of the superparticle in ten dimensions
We present a modification of the Berkovits superparticle. This is firstly in
order to covariantly quantize the pure spinor ghosts, and secondly to
covariantly calculate matrix elements of a generic operator between two states.
We proceed by lifting the pure spinor ghost constraints and regaining them
through a BRST cohomology. We are then able to perform a BRST quantization of
the system in the usual way, except for some interesting subtleties. Since the
pure spinor constraints are reducible, ghosts for ghosts terms are needed,
which have so far been calculated up to level 4. Even without a completion of
these terms, we are still able to calculate arbitrary matrix elements of a
physical operator between two physical states.Comment: 38 pages, Latex, no figures. Published versio
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