1,050 research outputs found

### Q-instantons

We construct the half-supersymmetric instanton solutions that are
electric-magnetically dual to the recently discussed half-supersymmetric
Q7-branes. We call these instantons `Q-instantons'. Whereas the D-instanton is
most conveniently described using the RR axion \chi and the dilaton \phi, the
Q-instanton is most conveniently described using a different set of fields
\chi' and T, where \chi' is an axionic scalar. The real part of the Q-instanton
on-shell action is a function of T and the imaginary part is linear in \chi'.
Discrete shifts of the axion \chi' correspond to PSL(2,Z) transformations that
are of finite order. These are e.g. pure S-duality transformations relating
weak and strongly coupled regimes. We argue that near each orbifold point of
the quantum axion-dilaton moduli space PSL(2,Z)\PSL(2,R)/SO(2) the higher order
R^4 terms in the string effective action contain contributions from an infinite
sum of single multiply-charged instantons with the Q-instantons corresponding
to the orbifold points \tau=i,\rho where \tau is the complex axion-dilaton
field.Comment: 29 pages, 1 figur

### p-Branes, D-Branes and M-Branes

We consider solutions to the string effective action corresponding to
p-Branes, D-Branes and M-Branes and discuss some of their properties.Comment: 8 pages, latex, uses sprocl.sty; talk given at the Workshop on Gauge
Theories, Applied Supersymmetry and Quantum Gravity (London, July 1996) and
the Strings '96 conference, ``Current Trends in String Theory'' (Santa
Barbara, July 1996

### Domain Walls on the Brane

We show that all branes admit worldvolume domain wall solutions. We find one
class of solutions for which the tension of the brane changes discontinuously
along the domain wall. These solutions are not supersymmetric. We argue that
there is another class of domain wall solutions which is supersymmetric. A
particular case concerns supersymmetric domain wall solutions on IIB D-5- and
NS-5-branes.Comment: 18 pages, Tex, uses phyzz

### Massive IIA supergravity from the topologically massive D-2-brane

The superfield equations of massive IIA supergravity, in the form of
constraints on the superspace geometry, are shown to be implied by
$\kappa$-symmetry of the topologically massive D-2-brane.Comment: 19 pp. Minor corrections. To appear in PL

### IIA/IIB Supergravity and Ten-forms

We perform a careful investigation of which p-form fields can be introduced
consistently with the supersymmetry algebra of IIA and/or IIB ten-dimensional
supergravity. In particular the ten-forms, also known as "top-forms", require a
careful analysis since in this case, as we will show, closure of the
supersymmetry algebra at the linear level does not imply closure at the
non-linear level. Consequently, some of the (IIA and IIB) ten-form potentials
introduced in earlier work of some of us are discarded. At the same time we
show that new ten-form potentials, consistent with the full non-linear
supersymmetry algebra can be introduced. We give a superspace explanation of
our work. All of our results are precisely in line with the predictions of the
E(11) algebra.Comment: 17 page

### Spectrum of Higher Derivative 6D Chiral Supergravity

Gauged off-shell Maxwell-Einstein supergravity in six dimensions with N=(1,0)
supersymmetry has a higher derivative extension afforded by a supersymmetrized
Riemann squared term. This theory admits a supersymmetric Minkowski x S^2
compactification with a U(1) monopole of unit charge on S^2. We determine the
full spectrum of the theory on this background. We also determine the spectrum
on a non-supersymmetric version of this compactification in which the monopole
charge is different from unity, and we find the peculiar feature that there are
massless gravitini in a representation of the S^2 isometry group determined by
the monopole charge.Comment: typos correcte

### Solitons on the Supermembrane

Energy bounds are derived for planar and compactified M2-branes in a
hyper-K\"ahler background. These bounds are saturated, respectively, by lump
and Q-kink solitons, which are shown to preserve a half of the worldvolume
supersymmetry. The Q-kinks have a dual IIB interpretation as strings that
migrate between fivebranes.Comment: 18 pp. Latex; v2: minor corrections, version as published in JHE

### N=2\ $W$-supergravity

We quantise the classical gauge theory of $N=2\ w_\infty$-supergravity and
show how the underlying $N=2$ super-$w_\infty$ algebra gets deformed into an
$N=2$ super-$W_\infty$ algebra. Both algebras contain the $N=2$ super-Virasoro
algebra as a subalgebra. We discuss how one can extract from these results
information about quantum $N=2\ W_N$-supergravity theories containing a finite
number of higher-spin symmetries with superspin $s\le N$. As an example we
discuss the case of quantum $N=2\ W_3$-supergravity.Comment: 44 page

### Type II Duality Symmetries in Six Dimensions

We discuss the different discrete duality symmetries in six dimensions that
act within and between (i) the 10-dimensional heterotic string compactified on
$T^4$, (ii) the 10-dimensional Type IIA string compactified on $K3$ and (iii)
the 10-dimensional Type IIB string compactified on $K3$. In particular we show
that the underlying group-theoretical structure of these discrete duality
symmetries is determined by the proper cubic group ${\cal C}/\Z_2$. Our group
theoretical interpretation leads to simple rules for constructing the explicit
form of the different discrete Type II duality symmetries in an arbitrary
background. The explicit duality rules we obtain are applied to construct dual
versions of the 6-dimensional chiral null model.Comment: 31 pages, 6 figures, epsfig.sty, late

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