8,811 research outputs found
The supermembrane revisited
The M2-brane is studied from the perspective of superembeddings. We review
the derivation of the M2-brane dynamics and the supergravity constraints from
the standard superembedding constraint and we discuss explicitly the induced
d=3, N=8 superconformal geometry on the worldvolume. We show that the gauged
supermembrane, for a target space with a U(1) isometry, is the standard
D2-brane in a type IIA supergravity background. In particular, the D2-brane
action, complete with the Dirac-Born-Infeld term, arises from the gauged
Wess-Zumino worldvolume 4-form via the brane action principle. The discussion
is extended to the massive D2-brane considered as a gauged supermembrane in a
massive D=11 superspace background. Type IIA supergeometry is derived using
Kaluza-Klein techniques in superspace.Comment: Latex, 46 pages, clarifying remarks and references adde
Strings and D-Branes with Boundaries
The covariant field equations of ten-dimensional super D-branes are obtained
by considering fundamental strings whose ends lie in the superworldsurface of
the D-brane. By considering in a similar fashion Dp-branes ending on
D(p+2)-branes we derive equations describing D-branes with dual potentials, as
well as the vector potentials.Comment: 12 pages, Late
On Brane Actions and Superembeddings
Actions for branes, with or without worldsurface gauge fields, are discussed
in a unified framework. A simple algorithm is given for constructing the
component Green-Schwarz actions. Superspace actions are also discussed. Three
examples are given to illustrate the general procedure: the membrane in D=11
and the D2-brane, which both have on-shell worldsurface supermultiplets, and
the membrane in D=4, which has an off-shell multiplet.Comment: 19 pages, late
L-branes
The superembedding approach to -branes is used to study a class of
-branes which have linear multiplets on the worldvolume. We refer to these
branes as L-branes. Although linear multiplets are related to scalar multiplets
(with 4 or 8 supersymmetries) by dualising one of the scalars of the latter to
a -form field strength, in many geometrical situations it is the linear
multiplet version which arises naturally. Furthermore, in the case of 8
supersymmetries, the linear multiplet is off-shell in contrast to the scalar
multiplet. The dynamics of the L-branes are obtained by using a systematic
procedure for constructing the Green-Schwarz action from the superembedding
formalism. This action has a Dirac-Born-Infeld type structure for the -form.
In addition, a set of equations of motion is postulated directly in superspace,
and is shown to agree with the Green-Schwarz equations of motion.Comment: revised version, minor changes, references added, 22 pages, no
figures, LaTe
Codimension One Branes
We study codimension one branes, i.e. p-branes in (p+2)-dimensions, in the
superembedding approach for the cases where the worldvolume superspace is
embedded in a minimal target superspace with half supersymmetry breaking. This
singles out the cases p=1,2,3,5,9. For p=3,5,9 the superembedding geometry
naturally involves a fundamental super 2-form potential on the worldvolume
whose generalised field strength obeys a constraint deducible from considering
an open supermembrane ending on the p-brane. This constraint, together with the
embedding constraint, puts the system on-shell for p=5 but overconstrains the
9-brane in D=11 such that the Goldstone superfield is frozen. For p=3 these two
constraints give rise to an off-shell linear multiplet on the worldvolume. An
alternative formulation of this case is given in which the linear multiplet is
dualised to an off-shell scalar multiplet. Actions are constructed for both
cases and are shown to give equivalent equations of motion. After gauge fixing
a local Sp(1) symmetry associated with shifts in the Sp(1)_R Goldstone modes,
we find that the auxiliary fields in the scalar multiplet parametrise a
two-sphere. For completeness we also discuss briefly the cases p=1,2 where the
equations of motion (for off-shell multiplets) are obtained from an action
principle.Comment: 38 pages, latex, cover page correcte
AdS/SCFT in Superspace
A discussion of the AdS/CFT correspondence in IIB is given in a superspace
context. The main emphasis is on the properties of SCFT correlators on the
boundary which are studied using harmonic superspace techniques. These
techniques provide the easiest way of implementing the superconformal Ward
identities. The Ward identities, together with analyticity, can be used to give
a compelling argument in support of the non-renormalisation theorems for two-
and three-point functions, and to establish the triviality of extremal and
next-to-extremal correlation functions. The OPE in is also briefly discussed.Comment: 10 pages; talk given by PSH at 2nd Gursey Memorial Conference, June
200
Volkov-Akulov theory and D-branes
The action of supersymmetric Born-Infeld theory (D-9-brane in a Lorentz
covariant static gauge) has a geometric form of the Volkov-Akulov-type. The
first non-linearly realized supersymmetry can be made manifest, the second
world-volume supersymmetry is not manifest. We also study the analogous 2
supersymmetries of the quadratic action of the covariantly quantized D-0-brane.
We show that the Hamiltonian and the BRST operator are build from these two
supersymmetry generators.Comment: 10 pages, Latex, Contribution to Supersymmetry and Quantum Field
Theory, International Seminar dedicated to the memory of D. V. Volkov
(Kharkov, 1997
On superembedding approach to type IIB 7-branes
In search for a dynamical description of Q7-branes, which were known as
solutions of supergravity equations and then conjectured to be dynamical
objects of type IIB string theory, we study the superembedding description of
7-branes in curved type IIB supergravity superspace. With quite minimal and
natural assumptions we have found that there is no place for Q7-branes as
dynamical branes in superembedding approach. Our study might give implications
for the old-standing problem of the covariant and supersymmetric description of
multiple Dp-brane systems.Comment: LaTeX, 40 pages, no figures. V2: 44 pages, misprints corrected, minor
cosmetic changes, improvements and extensions of discussion, in particular in
the parts devoted to derivation of D7-brane equations of motion (Sec. 3) and
in Secs. 4.2; appendices E,F added, footnote on page 30 extended, conclusions
remain the same. V3. More misprints correcte
Anomaly-Free Tensor-Yang-Mills System and Its Dual Formulation
We consider the (1,0) supersymmetric Yang-Mills multiplet coupled to a self-dual tensor multiplet in six dimensions. It is shown that the counterterm required to cancel the one-loop gauge anomaly modifies the classical equations of motion previously obtained by Bergshoeff, Sezgin and Sokatchev (BSS). We discuss the supermultiplet structure of the anomalies exhibited in the resulting equations of motion. The anomaly corrected field equations agree with the global limit, recently obtained by Duff, Liu, Lu and Pope, of a matter coupled supergravity theory in six dimensions. We also obtain the dual formulation of the BSS model in which the tensor multiplet is free while the field equations of the Yang-Mills multiplet contain the fields of the tensor multiplet at the classical level
Fibre Bundles and Generalised Dimensional Reduction
We study some geometrical and topological aspects of the generalised
dimensional reduction of supergravities in D=11 and D=10 dimensions, which give
rise to massive theories in lower dimensions. In these reductions, a global
symmetry is used in order to allow some of the fields to have a non-trivial
dependence on the compactifying coordinates. Global consistency in the internal
space imposes topological restrictions on the parameters of the
compactification as well as the structure of the space itself. Examples that we
consider include the generalised reduction of the type IIA and type IIB
theories on a circle, and also the massive ten-dimensional theory obtained by
the generalised reduction of D=11 supergravity.Comment: 23 pages, Late
- …