262 research outputs found
Two-Point Functions of Four-Dimensional Simplicial Quantum Gravity
We investigate the interaction mechanism of pure quantum gravity in Regge
discretization. We compute volume-volume and link-link correlation functions.
In a preliminary analysis the forces turn out to be of Yukawa type, at least on
our finite lattice being away from the continuum limit.Comment: 3 pages, uuencoded postscript file; Proceedings of the XI
International Symposion on Lattice Field Theory, Dallas, Oct. 199
Relating the Komargodski-Seiberg and Akulov-Volkov actions: Exact nonlinear field redefinition
This paper constructs an exact field redefinition that maps the Akulov-Volkov
action to that recently studied by Komargodski and Seiberg in arXiv:0907.2441.
It is also shown that the approach advocated in arXiv:1003.4143v2 and
arXiv:1009.2166 for deriving such a relationship is inconsistent.Comment: 8 pages; V2: a reference added, minor changes mad
The Quantum Geometry of N=(2,2) Non-Linear Sigma-Models
We consider a general N=(2,2) non-linear sigma-model in (2,2) superspace.
Depending on the details of the complex structures involved, an off-shell
description can be given in terms of chiral, twisted chiral and semi-chiral
superfields. Using superspace techniques, we derive the conditions the
potential has to satisfy in order to be ultra-violet finite at one loop. We pay
particular attention to the effects due to the presence of semi-chiral
superfields. A complete description of N=(2,2) strings follows from this.Comment: 9 pages, Late
The Semi-Chiral Quotient, Hyperkahler Manifolds and T-duality
We study the construction of generalized Kahler manifolds, described purely
in terms of N=(2,2) semichiral superfields, by a quotient using the semichiral
vector multiplet. Despite the presence of a b-field in these models, we show
that the quotient of a hyperkahler manifold is hyperkahler, as in the usual
hyperkahler quotient. Thus, quotient manifolds with torsion cannot be
constructed by this method. Nonetheless, this method does give a new
description of hyperkahler manifolds in terms of two-dimensional N=(2,2) gauged
non-linear sigma models involving semichiral superfields and the semichiral
vector multiplet. We give two examples: Eguchi-Hanson and Taub-NUT. By
T-duality, this gives new gauged linear sigma models describing the T-dual of
Eguchi-Hanson and NS5-branes. We also clarify some aspects of T-duality
relating these models to N=(4,4) models for chiral/twisted-chiral fields and
comment briefly on more general quotients that can give rise to torsion and
give an example.Comment: 31 page
On the Topology and Flux of T-Dual Manifolds
We present a general formula for the topology and H-flux of the T-dual of a
type two compactification. Our results apply to T-dualities with respect to any
free circle action. In particular we find that the manifolds on each side of
the duality are circle bundles whose curvatures are given by the integral of
the dual H-flux over the dual circle. As a corollary we conjecture an
obstruction to multiple T-dualities, generalizing an obstruction known to exist
on the twisted torus. Examples include SU(2) WZW models, Lens spaces and the
supersymmetric string theory on the non-spin AdS^5xCP^2xS^1 compactification.Comment: 4 Pages, No Figure
Space-Time Symmetries of Quantized Tensionless Strings
The tensionless limit of the free bosonic string is space-time conformally
symmetric classically. Requiring invariance of the quantum theory in the light
cone gauge tests the reparametrization symmetry needed to fix this gauge. The
full conformal symmetry gives stronger constraints than the Poincar\'e
subalgebra. We find that the symmetry may be preserved in any space-time
dimension, but only if the spectrum is drastically reduced (part of this
reduction is natural in a zero tension limit of the ordinary string spectrum).
The quantum states are required to be symmetric ({\it i.e.} singlets) under
space-time diffeomorphisms, except for the centre of mass wave function.Comment: 15pp, plain latex, USITP-92-
Nonlinear Supersymmetry, Brane-bulk Interactions and Super-Higgs without Gravity
We derive the coupling of a hypermultiplet of N=2 global supersymmetry to the
Dirac-Born-Infeld Maxwell theory with linear N=1 and a second nonlinear
supersymmetry. At the level of global supersymmetry, this construction
corresponds to the interaction with Maxwell brane fields of bulk
hypermultiplets, such as the universal dilaton of type IIB strings compactified
on a Calabi-Yau manifold. It displays in particular the active role of a
four-form field. Constrained N=1 and N=2 superfields and the formulation of the
hypermultiplet in its single-tensor version are used to derive the nonlinear
realization, allowing a fully off-shell description. Exact results with
explicit symmetries and supersymmetries are then obtained. The
electric-magnetic dual version of the theory is also derived and the gauge
structure of the interaction is exemplified with N=2 nonlinear QED of a charged
hypermultiplet. Its Higgs phase describes a novel super-Higgs mechanism without
gravity, where the goldstino is combined with half of the hypermultiplet into
an N=1 massive vector multiplet.Comment: 42 page
Dilaton transformation under abelian and non-abelian T-duality in the path integral approach
We present a convenient method for deriving the transformation of the dilaton
under T-duality in the path-integral approach. Subtleties arising in performing
the integral over the gauge fields are carefully analysed using Pauli-Villars
regularization, thereby clarifying existing ambiguities in the literature. The
formalism can not only be applied to the abelian case, but, and this for the
first time, to the non-abelian case as well. Furthermore, by choosing a
particular gauge, we directly obtain the target-space covariant expression for
the dual geometry in the abelian case. Finally it is shown that the conditions
for gauging non-abelian isometries are weaker than those generally found in the
literature.Comment: latex, 20 pages, no figure
Properties of Semi-Chiral Superfields
Whenever the N=(2,2) supersymmetry algebra of non-linear sigma-models in two
dimensions does not close off-shell, a holomorphic two-form can be defined. The
only known superfields providing candidate auxiliary fields to achieve an
off-shell formulation are semi-chiral fields. Such a semi-chiral description is
only possible when the two-form is constant. Using an explicit example,
hyper-Kahler manifolds, we show that this is not always the case. Finally, we
give a concrete construction of semi-chiral potentials for a class of
hyper-Kahler manifolds using the duality exchanging a pair consisting of a
chiral and a twisted-chiral superfield for one semi-chiral multiplet.Comment: LaTeX, 17 page
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