319 research outputs found
The Power of M Theory
A proposed duality between type IIB superstring theory on R^9 X S^1 and a
conjectured 11D fundamental theory (``M theory'') on R^9 X T^2 is investigated.
Simple heuristic reasoning leads to a consistent picture relating the various
p-branes and their tensions in each theory. Identifying the M theory on R^{10}
X S^1 with type IIA superstring theory on R^{10}, in a similar fashion, leads
to various relations among the p-branes of the IIA theory.Comment: 13 pages; late
Duality Symmetries of 4D Heterotic Strings
Target space duality (T duality), which interchanges Kaluza--Klein and
winding-mode excitations of the compactified heterotic string, is realized as a
symmetry of a world-sheet action. Axion-dilaton duality (S duality), a
conjectured nonperturbative SL(2,Z) symmetry of the same theory, plays an
analogous role for five-branes. We describe a soliton spectrum possessing both
duality symmetries and argue that the theory has an infinite number of dual
string descriptions.Comment: 16 pages, NSF-ITP-93-6
Superstring Dualities
This talk is divided into two parts. The first part reviews some of the
duality relationships between superstring theories. These relationships are
interpreted as providing evidence for the existence of a unique underlying
fundamental theory. The second part describes my recent work on the SL(2,Z)
duality group of the type IIB superstring theory in ten dimensions and its
interpretation in terms of a possible theory of supermembranes in eleven
dimensions.Comment: 14 pages; latex; an error has been correcte
Classical Symmetries of Some Two-Dimensional Models Coupled to Gravity
This paper is a sequel to one in which we examined the affine symmetry
algebras of arbitrary classical principal chiral models and symmetric space
models in two dimensions. It examines the extension of those results in the
presence of gravity. The main result is that even though the symmetry
transformations of the fields depend on the gravitational background, the
symmetry algebras of these classical theories are completely unchanged by the
presence of arbitrary gravitational backgrounds. On the other hand, we are
unable to generalize the Virasoro symmetries of the flat-space theories to
theories with gravity.Comment: 22 pages, late
Interacting Chiral Gauge Fields in Six Dimensions and Born-Infeld Theory
Dimensional reduction of a self-dual tensor gauge field in 6d gives an
Abelian vector gauge field in 5d. We derive the conditions under which an
interacting 5d theory of an Abelian vector gauge field is the dimensional
reduction of a 6d Lorentz invariant interacting theory of a self-dual tensor.
Then we specialize to the particular 6d theory that gives 5d Born-Infeld
theory. The field equation and Lagrangian of this 6d theory are formulated with
manifest 5d Lorentz invariance, while the remaining Lorentz symmetries are
realized nontrivially. A string soliton with finite tension and self-dual
charge is constructed.Comment: 22 pages, latex, no figure
Lectures on Superstring and M Theory Dualities
These lectures begin by reviewing the evidence for S duality of the
toroidally compactified heterotic string in 4d that was obtained in the period
1992--94. Next they review recently discovered dualities that relate all five
of the 10d superstring theories and a quantum extension of 11d supergravity
called M theory. The study of p-branes of various dimensions (some of which are
D-branes) plays a central role. The final sections survey supersymmetric string
vacua in 6d and some of the dual constructions by which they can be obtained.
Special emphasis is given to a class of N=1 models that exhibit
``heterotic-heterotic duality.''Comment: 67 pages, latex, 1 figure; Lectures given at the ICTP Spring School
(March 1996) and the TASI Summer School (June 1996), TASI9
Anomaly-Free Supersymmetric Models in Six Dimensions
The conditions for the cancellation of all gauge, gravitational, and mixed
anomalies of supersymmetric models in six dimensions are reviewed and
illustrated by a number of examples. Of particular interest are models that
cannot be realized perturbatively in string theory. An example of this type,
which we verify satisfies the anomaly cancellation conditions, is the K3
compactification of the theory with small instantons recently proposed
by Witten. When the instantons coincide it has gauge group . Two new classes of models, for which non-perturbative string
constructions are not yet known, are also presented. They have gauge groups
and , where is an arbitrary
positive integer.Comment: 14 pages, latex; A paragraph in section 4 has been replace
Gauge-Invariant and Gauge-Fixed D-Brane Actions
The first part of this paper presents actions for Dirichlet p-branes embedded
in a flat 10-dimensional space-time. The fields of the (p+1)-dimensional
world-volume theories are the 10d space-time coordinates , a pair of
Majorana-Weyl spinors and , and a U(1) gauge field
. The N = 2A or 2B super-Poincare group in ten dimensions is realized
as a global symmetry. In addition, the theories have local symmetries
consisting of general coordinate invariance of the world volume, a local
fermionic symmetry (called ``kappa''), and U(1) gauge invariance. A detailed
proof of the kappa symmetry is given that applies to all cases (p = 0,1, . . .,
9). The second part of the paper presents gauge-fixed versions of these
theories. The fields of the 10d (p = 9) gauge-fixed theory are a single
Majorana-Weyl spinor and the U(1) gauge field . This theory,
whose action turns out to be surprisingly simple, is a supersymmetric extension
of 10d Born-Infeld theory. It has two global supersymmetries: one represents an
unbroken symmetry, and the second corresponds to a broken symmetry for which
is the Goldstone fermion. The gauge-fixed supersymmetric D-brane
theories with can be obtained from the 10d one by dimensional reduction.Comment: 33 pages, latex, no figures; revised as requested by refere
Wrapping the M Theory Five-Brane on K3
Using a recently constructed M5-brane world-volume action, we demonstrate
that wrapping the M5-brane on K3 gives the heterotic string in seven
dimensions. To facilitate the comparison, a new version of the world-sheet
action for the Narain-compactified heterotic string, with manifest T duality
invariance, is formulated.Comment: 14 pages, latex, no figures; an error has been correcte
Anomalies, Dualities, and Topology of D=6 N=1 Superstring Vacua
We consider various aspects of compactifications of the Type I/heterotic
theory on K3. One family of such compactifications includes the
standard embedding of the spin connection in the gauge group, and is on the
same moduli space as the compactification of the heterotic
theory on K3 with instanton numbers (8,16). Another class, which includes an
orbifold of the Type I theory recently constructed by Gimon and Polchinski and
whose field theory limit involves some topological novelties, is on the moduli
space of the heterotic theory on K3 with instanton numbers
(12,12). These connections between and models
can be demonstrated by T duality, and permit a better understanding of
non-perturbative gauge fields in the (12,12) model. In the transformation
between and models, the strong/weak coupling
duality of the (12,12) model is mapped to T duality in the Type
I theory. The gauge and gravitational anomalies in the Type I theory are
canceled by an extension of the Green-Schwarz mechanism.Comment: 48 page
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