3,490 research outputs found
The Design of Fail-Safe Logic
This paper examines the behavior of digital logic families, specifically identifying the properties and characteristics of digital fail-safe logic. Fail-safe digital design is examined utilizing classical logic and semiconductor theory. The effects of failures internal to the structure of digital integrated circuits are analyzed and a discussion of pertinent logic design is presented. The techniques to detect all types of multiple failure modes are examined. With these results, a method of design for fail-safe logic is presented and analyzed
Mirror Symmetry is T-Duality
It is argued that every Calabi-Yau manifold with a mirror admits a
family of supersymmetric toroidal 3-cycles. Moreover the moduli space of such
cycles together with their flat connections is precisely the space . The
mirror transformation is equivalent to T-duality on the 3-cycles. The geometry
of moduli space is addressed in a general framework. Several examples are
discussed.Comment: 20 pages, harvmac -- some references added, typos correcte
D-Branes and Spin^c Structures
It was recently pointed out by E. Witten that for a D-brane to consistently
wrap a submanifold of some manifold, the normal bundle must admit a Spin^c
structure. We examine this constraint in the case of type II string
compactifications with vanishing cosmological constant, and argue that in all
such cases, the normal bundle to a supersymmetric cycle is automatically
Spin^c.Comment: 9 pages, LaTe
Equations of Motion and Galilei Invariance in D-Particle Dynamics
As a continuation of our previous work on the multi-body forces of
D-particles in supergravity and Matrix theory, we investigate the problem of
motion. We show that the scattering of D-particles including recoil derived in
Matrix theory is precisely reproduced by supergravity with the discrete
light-cone prescription up to the second order in 11 dimensional Newton
constant. An intimate connection of recoil and Galilei invariance in
supergravity is pointed out and elucidated.Comment: 19 pages, no figures, LaTe
D-branes in Kazama-Suzuki Models
We investigate boundary states of D-branes wrapped around supersymmetric
cycles in Kazama--Suzuki models. We show that the geometry of the D-branes
corresponds to a generalisation of calibrated geometry. We comment on the link
with the geometry of the coset space and discuss how T-duality maps between
these boundary states.Comment: 17 pages, final version to appear in Nucl. Phys.
Supersymmetric Three-cycles and (Super)symmetry Breaking
We describe physical phenomena associated with a class of transitions that
occur in the study of supersymmetric three-cycles in Calabi-Yau threefolds. The
transitions in question occur at real codimension one in the complex structure
moduli space of the Calabi-Yau manifold. In type IIB string theory, these
transitions can be used to describe the evolution of a BPS state as one moves
through a locus of marginal stability: at the transition point the BPS particle
becomes degenerate with a supersymmetric two particle state, and after the
transition the lowest energy state carrying the same charges is a
non-supersymmetric two particle state. In the IIA theory, wrapping the cycles
in question with D6-branes leads to a simple realization of the Fayet model:
for some values of the CY modulus gauge symmetry is spontaneously broken, while
for other values supersymmetry is spontaneously broken.Comment: 10 pages, harvmac big; v2, minor change
Short Distance Contributions to Graviton-Graviton Scattering: Matrix Theory versus Supergravity
We study graviton scattering in the presence of higher dimensional operators
- particularly, R^4 - arising from loop effects. We find that the results do
not correspond to any known terms in the effective action of Matrix Theory,
thus lending support to the idea that the finite N Matrix Theory has no simple
relation to supergravity with large compactification radii.Comment: 13 pages, LaTeX file with 3 Postscript figures. Uses epsf.tex and
fps.sty macros. Revisions of v2: some comments in the end of section 3 have
been remove
Nonsupersymmetric String Solitons
We begin a search for nonsupersymmetric/supersymmetric dual string pairs by
constructing candidate critical nonsupersymmetric strings as solitons in
supersymmetric string theories. Using orbifold techniques, one can construct
cosmic string solutions which lie in supersymmetric vacua but which do not fall
in supermultiplets. We discuss two three-dimensional examples in detail. The
effective worldsheet actions for the soliton strings have (0,2) and (1,1)
supersymmetry and the correct numbers of massless bosons and fermions to be
critical heterotic and type II strings, respectively.Comment: 14 pages, harvmac bi
Euclidean D-branes and higher-dimensional gauge theory
We consider euclidean D-branes wrapping around manifolds of exceptional
holonomy in dimensions seven and eight. The resulting theory on the
D-brane---that is, the dimensional reduction of 10-dimensional supersymmetric
Yang-Mills theory---is a cohomological field theory which describes the
topology of the moduli space of instantons. The 7-dimensional theory is an N_T
= 2 (or balanced) cohomological theory given by an action potential of
Chern-Simons type. As a by-product of this method, we construct a related
cohomological field theory which describes the monopole moduli space on a
7-manifold of G_2 holonomy.Comment: 23 pages (some changes in section 4.5 -- equations 27 and 28 change
slightly) (missing bibliography added!
Supersymmetric completion of supersymmetric quantum mechanics
Via supersymmetry argument, we determine the effective action of the SU(2)
supersymmetric Yang-Mills quantum mechanics up to two constants, which results
from the full supersymmetric completion of the F^4 term. The effective action,
consisting of zero, two, four, six and eight fermion terms, agrees with the
known perturbative one-loop calculations from the type II string theory and the
matrix theory. Our derivation thus demonstrates its non-renormalization
properties, namely, the one-loop exactness of the aforementioned action and the
absence of the non-perturbative corrections. We briefly discuss generalizations
to other branes and the comparison to the DLCQ supergravity analysis. In
particular, our results show that the stringent constraints from the
supersymmetry are responsible for the agreement between the matrix theory and
supergravity with sixteen supercharges.Comment: 26 pages, LaTeX, no figure
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