8,756 research outputs found
The Covariant Quantum Superstring and Superparticle from their Classical Actions
We develop an approach based on the Noether method to construct nilpotent
BRST charges and BRST-invariant actions. We apply this approach first to the
holomorphic part of the flat-space covariant superstring, and we find that the
ghosts b, c_z which we introduced by hand in our earlier work, are needed to
fix gauge symmetries of the ghost action. Then we apply this technique to the
superparticle and determine its cohomology. Finally, we extend our results to
the combined left- and right-moving sectors of the superstring.Comment: 14 pages, harmva
Harmonic Superspaces from Superstrings
We derive harmonic superspaces for N=2,3,4 SYM theory in four dimensions from
superstring theory. The pure spinors in ten dimensions are dimensionally
reduced and yield the harmonic coordinates. Two anticommuting BRST charges
implement Grassmann analyticity and harmonic analyticity. The string field
theory action produces the action and field equations for N=3 SYM theory in
harmonic superspace.Comment: 14 pp. Harvma
N=4 Superconformal Symmetry for the Covariant Quantum Superstring
We extend our formulation of the covariant quantum superstring as a WZNW
model with N=2 superconformal symmetry to N=4. The two anticommuting BRST
charges in the N=4 multiplet of charges are the usual BRST charge Q_S and a
charge Q_V proposed by Dijkgraaf, Verlinde and Verlinde for topological models.
Using our recent work on "gauging cosets", we then construct a further charge
Q_C which anticommutes with Q_S + Q_V and which is intended for the definition
of the physical spectrum.Comment: LaTeX, 18 pages, no figure
Non-Critical Covariant Superstrings
We construct a covariant description of non-critical superstrings in even
dimensions. We construct explicitly supersymmetric hybrid type variables in a
linear dilaton background, and study an underlying N=2 twisted superconformal
algebra structure. We find similarities between non-critical superstrings in
2n+2 dimensions and critical superstrings compactified on CY_(4-n) manifolds.
We study the spectrum of the non-critical strings, and in particular the
Ramond-Ramond massless fields. We use the supersymmetric variables to construct
the non-critical superstrings sigma-model action in curved target space
backgrounds with coupling to the Ramond-Ramond fields. We consider as an
example non-critical type IIA strings on AdS_2 background with Ramond-Ramond
2-form flux.Comment: harvmac, amssym, 46 p
Aspects of Quantum Fermionic T-duality
We study two aspects of fermionic T-duality: the duality in purely fermionic
sigma models exploring the possible obstructions and the extension of the
T-duality beyond classical approximation. We consider fermionic sigma models as
coset models of supergroups divided by their maximally bosonic subgroup
OSp(m|n)/SO(m) x Sp(n). Using the non-abelian T-duality and a non-conventional
gauge fixing we derive their fermionic T-duals. In the second part of the
paper, we prove the conformal invariance of these models at one and two loops
using the Background Field Method and we check the Ward Identities.Comment: 65 pages, 5 figure
The Background Field Method and the Linearization Problem for Poisson Manifolds
The background field method (BFM) for the Poisson Sigma Model (PSM) is
studied as an example of the application of the BFM technique to open gauge
algebras. The relationship with Seiberg-Witten maps arising in non-commutative
gauge theories is clarified. It is shown that the implementation of the BFM for
the PSM in the Batalin-Vilkovisky formalism is equivalent to the solution of a
generalized linearization problem (in the formal sense) for Poisson structures
in the presence of gauge fields. Sufficient conditions for the existence of a
solution and a constructive method to derive it are presented.Comment: 33 pp. LaTex, references and comments adde
Curved Beta-Gamma Systems and Quantum Koszul Resolution
We consider the partition function of beta-gamma systems in curved space of
the type discussed by Nekrasov and Witten. We show how the Koszul resolution
theorem can be applied to the computation of the partition functions and to
characters of these systems and find a prescription to enforce the hypotheses
of the theorem at the path integral level. We illustrate the technique in a few
examples: a simple 2-dimensional target space, the N-dimensional conifold, and
a superconifold. Our method can also be applied to the Pure Spinor constraints
of superstrings.Comment: harvmac, 17 page
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