483 research outputs found
A note on W_{2,s} strings
BRST operators for two-dimensional theories with spin-2 and spin-
currents, generalising the BRST operator of Thierry-Mieg, have previously
been obtained. The construction was based on demanding nilpotence of the BRST
operators, making no reference to whether or not an underlying algebra
exists. In this paper, we analyse the known cases (, 4, 5 and 6), showing
that the two BRST operators are associated with the algebra, and
that two of the four BRST operators are associated with the
algebra. We discuss the cohomology of all the known higher-spin BRST operators,
the Weyl symmetry of their physical states, and their relation with certain
minimal models. We also obtain the BRST operator for the case .Comment: 12 pages, CTP TAMU-8/94, LZU-TH-94/0
N=2 Superstrings with (1,2m) Spacetime Signature
We show that the superstring in 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 real spacetime signature. Norm
calculations for low-lying physical states suggest that the theory is ghost
free.Comment: 8 page
Anomaly Freedom and Realisations for Super- Strings
We construct new multi-field realisations of the super- algebra,
which are important for building super- 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- string theory.Comment: 22 page
The Complete Spectrum of the String
We obtain the complete physical spectrum of the string, for arbitrary
. The constraints freeze 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 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 strings are unitary.Comment: 28 page
The Interacting String
We present a procedure for computing gauge-invariant scattering amplitudes in
the 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
string, with different sets of intermediate states being exchanged in different
channels. We also exhibit a relation between the scattering amplitudes of the
string and the fusion rules of the Ising model.Comment: (Revised version), 26 pages, Plain Tex, CTP TAMU-86/92, KUL-TF-92/4
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
Supergravities with Minkowski x Sphere Vacua
Recently the authors have introduced a new gauged supergravity theory with a
positive definite potential in D=6, obtained through a generalised Kaluza-Klein
reduction from D=7. Of particular interest is the fact that this theory admits
certain Minkowski x Sphere vacua. In this paper we extend the previous results
by constructing gauged supergravities with positive definitive potentials in
diverse dimensions, together with their vacuum solutions. In addition, we prove
the supersymmetry of the generalised reduction ansatz. We obtain a
supersymmetric solution with no form-field fluxes in the new gauged theory in
D=9. This solution may be lifted to D=10, where it acquires an interpretation
as a time-dependent supersymmetric cosmological solution supported purely by
the dilaton. A further uplift to D=11 yields a solution describing a pp-wave.Comment: Latex, 26 pages, typos correcte
On Sibling and Exceptional W Strings
We discuss the physical spectrum for strings based on the algebras ,
, , and . For a simply-laced string, we find a
connection with the unitary Virasoro minimal model, where is the
dual Coxeter number of the underlying Lie algebra. For the string based on
, we find a connection with the unitary super-Virasoro
minimal model.Comment: 16 page
Yang-Mills Interactions and Gravity in Terms of Clifford Algebra
A model of Yang-Mills interactions and gravity in terms of the Clifford
algebra Cl(0,6) is presented. The gravity and Yang-Mills actions are formulated
as different order terms in a generalized action. The feebleness of gravity as
well as the smallness of the cosmological constant and theta terms are
discussed at the classical level. The invariance groups, including the de
Sitter and the Pati-Salam SU(4) subgroups, consist of gauge transformations
from either side of an algebraic spinor. Upon symmetry breaking via the Higgs
fields, the remaining symmetries are the Lorentz SO(1,3), color SU(3),
electromagnetic U(1)_EM, and an additional U(1). The first generation leptons
and quarks are identified with even and odd parts of spinor idempotent
projections. There are still several shortcomings with the current model.
Further research is needed to fully recover the standard model results.Comment: 20 pages, to appear in Advances in Applied Clifford Algebra
Domain Walls in Massive Supergravities
We show how toroidally-compactified eleven-dimensional supergravity can be
consistently truncated to yield a variety of maximally-supersymmetric
``massive'' supergravities in spacetime dimensions . The mass terms
arise as a consequence of making a more general ansatz than that in usual
Kaluza-Klein dimensional reduction, in which one or more axions are given an
additional linear dependence on one of the compactification coordinates. The
lower-dimensional theories are nevertheless consistent truncations of
eleven-dimensional supergravity. Owing to the fact that the generalised
reduction commutes neither with U-duality nor with ordinary dimensional
reduction, many different massive theories can result. The simplest examples
arise when just a single axion has the additional linear coordinate dependence.
We find five inequivalent such theories in D=7, and 71 inequivalent ones in
D=4. The massive theories admit no maximally-symmetric vacuum solution, but
they do admit -brane solutions, i.e. domain walls, which preserve half
the supersymmetry. We present examples of these solutions, and their oxidations
to D=11. Some of the latter are new solutions of D=11 supergravity.Comment: latex, 32 papes, no figures, further comments and references adde
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