393 research outputs found

### The $W_3$-string spectrum

We study the spectrum of $W_3$ strings. In particular, we show that for
appropriately chosen space-time signature, one of the scalar fields is singled
out by the spin-3 constraint and is ``frozen'': no creation operators from it
can appear in physical states and the corresponding momentum must assume a
specific fixed value. The remaining theory is unitary and resembles an ordinary
string theory in $d\ne26$ with anomalies cancelled by appropriate background
charges. In the case of the $W_3$ string, however, the spin-two ``graviton'' is
massive.Comment: 14 Page

### Anomaly Freedom and Realisations for Super-$W_3$ Strings

We construct new multi-field realisations of the $N=2$ super-$W_3$ algebra,
which are important for building super-$W_3$ string theories. We derive the
structure of the ghost vacuum for such theories, and use the result to
calculate the intercepts. These results determine the conditions for physical
states in the super-$W_3$ string theory.Comment: 22 page

### The Complete Spectrum of the $W_N$ String

We obtain the complete physical spectrum of the $W_N$ string, for arbitrary
$N$. The $W_N$ constraints freeze $N-2$ coordinates, while the remaining
coordinates appear in the currents only {\it via} their energy-momentum tensor.
The spectrum is then effectively described by a set of ordinary Virasoro-like
string theories, but with a non-critical value for the central charge and a
discrete set of non-standard values for the spin-2 intercepts. In particular,
the physical spectrum of the $W_N$ string includes the usual massless states of
the Virasoro string. By looking at the norms of low-lying states, we find
strong indications that all the $W_N$ strings are unitary.Comment: 28 page

### A Dielectric Flow Solution with Maximal Supersymmetry

We obtain a solution to eleven-dimensional supergravity that consists of
M2-branes embedded in a dielectric distribution of M5-branes. Contrary to
normal expectations, this solution has maximal supersymmetry for a brane
solution (i.e. sixteen supercharges). While the solution is constructed using
gauged supergravity in four dimensions, the complete eleven-dimensional
solution is given. In particular, we obtain the Killing spinors explicitly, and
we find that they are characterised by a duality rotation of the standard
Dirichlet projection matrix for M2-branes.Comment: 17 pages; harvma

### The Interacting $W_3$ String

We present a procedure for computing gauge-invariant scattering amplitudes in
the $W_3$ string, and use it to calculate three-point and four-point functions.
We show that non-vanishing scattering amplitudes necessarily involve external
physical states with excitations of ghosts as well as matter fields. The
crossing properties of the four-point functions are studied, and it is shown
that the duality of the Virasoro string amplitudes generalises in the $W_3$
string, with different sets of intermediate states being exchanged in different
channels. We also exhibit a relation between the scattering amplitudes of the
$W_3$ string and the fusion rules of the Ising model.Comment: (Revised version), 26 pages, Plain Tex, CTP TAMU-86/92, KUL-TF-92/4

### BRST Quantisation of the N=2 String in a Real Spacetime Structure

We study the $N=2$ string with a real structure on the $(2,2)$ spacetime,
using BRST methods. Several new features emerge. In the diagonal basis, the
operator $\exp(\lambda \int^z J^{\rm tot})$, which is associated with the
moduli for the $U(1)$ gauge field on the world-sheet, is local and it relates
the physical operators in the NS and R sectors. However, the picture-changing
operators are non-invertible in this case, and physical operators in different
pictures cannot be identified. The three-point interactions of all physical
operators leads to three different types of amplitudes, which can be
effectively described by the interactions of a scalar NS operator and a bosonic
spinorial R operator. In the off-diagonal bases for the fermionic currents, the
picture-changing operators are invertible, and hence physical operators in
different pictures can be identified. However, now there is no local operator
$\exp(\lambda \int^z J^{\rm tot})$ that relates the physical operators in
different sectors. The physical spectrum is thus described by one scalar NS
operator and one spinorial R operator. The NS and R operators give rise to
different types of three-point amplitudes, and thus cannot be identified.Comment: 17 pages, latex, no figures. Significant revisions, with extended
discussion of cohomology in different bases for fermionic current

### On Sibling and Exceptional W Strings

We discuss the physical spectrum for $W$ strings based on the algebras $B_n$,
$D_n$, $E_6$, $E_7$ and $E_8$. For a simply-laced $W$ string, we find a
connection with the $(h,h+1)$ unitary Virasoro minimal model, where $h$ is the
dual Coxeter number of the underlying Lie algebra. For the $W$ string based on
$B_n$, we find a connection with the $(2h,2h+2)$ unitary $N=1$ super-Virasoro
minimal model.Comment: 16 page

### N=2 Superstrings with (1,2m) Spacetime Signature

We show that the $N=2$ superstring in $d=2D\ge6$ real dimensions, with
criticality achieved by including background charges in the two real time
directions, exhibits a ``coordinate-freezing'' phenomenon, whereby the momentum
in one of the two time directions is constrained to take a specific value for
each physical state. This effectively removes this time direction as a physical
coordinate, leaving the theory with $(1,d-2)$ real spacetime signature. Norm
calculations for low-lying physical states suggest that the theory is ghost
free.Comment: 8 page

### Brane Resolution Through Transgression

Modifications to the singularity structure of D3-branes that result from
turning on a flux for the R-R and NS-NS 3-forms (fractional D3-branes) provide
important gravity duals of four-dimensional N=1 super-Yang-Mills theories. We
construct generalisations of these modified p-brane solutions in a variety of
other cases, including heterotic 5-branes, dyonic strings, M2-branes,
D2-branes, D4-branes and type IIA and type IIB strings, by replacing the flat
transverse space with a Ricci-flat manifold M_n that admits covariantly
constant spinors, and turning on a flux built from a harmonic form in M_n, thus
deforming the original solution and introducing fractional branes. The
construction makes essential use of the Chern-Simons or ``transgression'' terms
in the Bianchi-identity or equation of motion of the field strength that
supports the original undeformed solution. If the harmonic form is L^2
normalisable, this can result in a deformation of the brane solution that is
free of singularities, thus providing viable gravity duals of field theories in
diverse dimensions that have less than maximal supersymmetry. We obtain
examples of non-singular heterotic 5-branes, dyonic strings, M2-branes, type
IIA strings, and D2-branes.Comment: Latex 3 times, 35 page

### Five-dimensional N=4, SU(2) X U(1) Gauged Supergravity from Type IIB

We construct the complete and explicit non-linear Kaluza-Klein ansatz for
deriving the bosonic sector of N=4 SU(2)\times U(1) gauged five-dimensional
supergravity from the reduction of type IIB supergravity on S^5. This provides
the first complete example of such an S^5 reduction that includes non-abelian
gauge fields, and it allows any bosonic solution of the five-dimensional N=4
gauged theory to be embedded in D=10.Comment: latex, 12 page

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