12,801 research outputs found
Lower-dimensional pure-spinor superstrings
We study to what extent it is possible to generalise Berkovits' pure-spinor
construction in d=10 to lower dimensions. Using a suitable definition of a
``pure'' spinor in d=4,6, we propose models analogous to the d=10 pure-spinor
superstring in these dimensions. Similar models in d=2,3 are also briefly
discussed.Comment: 17 page
An Introduction to the Covariant Quantization of Superstrings
We give an introduction to a new approach to the covariant quantization of
superstrings. After a brief review of the classical Green--Schwarz superstring
and Berkovits' approach to its quantization based on pure spinors, we discuss
our covariant formulation without pure spinor constraints. We discuss the
relation between the concept of grading, which we introduced to define vertex
operators, and homological perturbation theory, and we compare our work with
recent work by others. In the appendices, we include some background material
for the Green-Schwarz and Berkovits formulations, in order that this
presentation be self contained.Comment: LaTex, 23 pp. Contribution to the Proceedings of the Workshop in
String Theory, Leuven 2002, some references added and a comment on ref. [16
The Algebraic Method
Combining the effect of an intermediate renormalization prescription (zero
momentum subtraction) and the background field method (BFM), we show that the
algebraic renormalization procedure needed for the computation of radiative
corrections within non-invariant regularization schemes is drastically
simplified. The present technique is suitable for gauge models and, here, is
applied to the Standard Model. The use of the BFM allows a powerful
organization of the counterterms and avoids complicated Slavnov-Taylor
identities. Furthermore, the Becchi-Rouet-Stora-Tyutin (BRST) variation of
background fields plays a special role in disentangling Ward-Takahashi
identities (WTI) and Slavnov-Taylor identities (STI). Finally, the strategy to
be applied to physical processes is exemplified for the process .Comment: Latex, 38 page
BFT embedding of the Green-Schwarz superstring and the pure spinor formalism
We worked out the Batalin-Fradkin-Tyutin (BFT) conversion program of second
class constraints to first class constraints in the GS superstring using light
cone coordinates. By applying this systematic procedure we were able to obtain
a gauge system that is equivalent to the recent model proposed by Berkovits and
Marchioro to relate the GS superstring to the pure spinor formalism.Comment: 12 pages latex2e, v2 typos fixed, v3 published in JHE
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
Minimal Supergravity and the supersymmetry of Arnold-Beltrami Flux branes
In this paper we study some properties of the newly found Arnold-Beltrami
flux-brane solutions to the minimal supergravity. To this end we first
single out the appropriate Free Differential Algebra containing both a gauge
-form and a gauge -form : then we
present the complete rheonomic parametrization of all the generalized
curvatures. This allows us to identify two-brane configurations with
Arnold-Beltrami fluxes in the transverse space with exact solutions of
supergravity and to analyze the Killing spinor equation in their background. We
find that there is no preserved supersymmetry if there are no additional
translational Killing vectors. Guided by this principle we explicitly construct
Arnold-Beltrami flux two-branes that preserve , and of the
original supersymmetry. Two-branes without fluxes are instead BPS states and
preserve supersymmetry. For each two-brane solution we carefully study
its discrete symmetry that is always given by some appropriate crystallographic
group . Such symmetry groups are transmitted to the
gauge theories on the brane world--volume that occur in the gauge/gravity
correspondence. Furthermore we illustrate the intriguing relation between gauge
fluxes in two-brane solutions and hyperinstantons in topological
sigma-models.Comment: 56 pages, LaTeX source, 8 jpg figures, typos correcte
Pure Spinor Superstrings on Generic type IIA Supergravity Backgrounds
We derive the Free Differential Algebra for type IIA supergravity in 10
dimensions in the string frame. We provide all fermionic terms for all
curvatures. We derive the Green-Schwarz sigma model for type IIA superstring
based on the FDA construction and we check its invariance under kappa-symmetry.
Finally, we derive the pure spinor sigma model and we check the BRST
invariance. The present derivation has the advantage that the resulting sigma
model is constructed in terms of the superfields appearing in the FDA and
therefore one can directly relate a supergravity background with the
corresponding sigma model. The complete explicit form of the BRST
transformations is given and some new pure spinor constraints are obtained.
Finally, the explicit form of the action is given.Comment: 31 pp. no figures, latex, some modifications at pag 21, a missing
term in 4.51 corrected. Discussion on BRST symmetry improve
Towards Pure Spinor Type Covariant Description of Supermembrane -- An Approach from the Double Spinor Formalism --
In a previous work, we have constructed a reparametrization invariant
worldsheet action from which one can derive the super-Poincare covariant pure
spinor formalism for the superstring at the fully quantum level. The main idea
was the doubling of the spinor degrees of freedom in the Green-Schwarz
formulation together with the introduction of a new compensating local
fermionic symmetry. In this paper, we extend this "double spinor" formalism to
the case of the supermembrane in 11 dimensions at the classical level. The
basic scheme works in parallel with the string case and we are able to
construct the closed algebra of first class constraints which governs the
entire dynamics of the system. A notable difference from the string case is
that this algebra is first order reducible and the associated BRST operator
must be constructed accordingly. The remaining problems which need to be solved
for the quantization will also be discussed.Comment: 40 pages, no figure, uses wick.sty; v2: a reference added, published
versio
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