1,472 research outputs found
Supersymmetry Breakdown at a Hidden Wall
We consider hidden sector supersymmetry breakdown in the strongly coupled
heterotic theory of Ho\v{r}ava and Witten. Using effective
field theory methods in four dimensions, we can show that gravitational
interactions induce soft breaking terms in the observable sector that are of
order of the gravitiono mass. We apply these methods to the mechanism of
gaugino condensation at the hidden wall. Although the situation is very similar
to the weakly coupled case, there is a decisive difference concerning the
observable sector gaugino mass; with desirable phenomenological as well as
cosmological consequences.Comment: 29 pages, latex, no figures, To appear in Nuclear Physics B. Minor
change
Thermal and electrical contact conductance studies
Prediction of electrical and thermal contact resistance for pressed, nominally flat contacts is complicated by the large number of variables which influence contact formation. This is reflected in experimental results as a wide variation in contact resistances, spanning up to six orders of magnitude. A series of experiments were performed to observe the effects of oxidation and surface roughness on contact resistance. Electrical contact resistance and thermal contact conductance from 4 to 290 K on OFHC Cu contacts are reported. Electrical contact resistance was measured with a 4-wire DC technique. Thermal contact conductance was determined by steady-state longitudinal heat flow. Corrections for the bulk contribution ot the overall measured resistance were made, with the remaining resistance due solely to the presence of the contact
Multiple anomalous U(1)s in heterotic blow-ups
The existence of multiple anomalous U(1)s is demonstrated explicitly in a
blow-up version of a heterotic Z_3 orbifold. Another blow-up of the same
orbifold supports further evidence for the type-I/heterotic duality in four
dimensions. It has a single anomalous U(1) which does not factorize
universally. As multiple anomalous U(1)s as well as non-universal factorization
have never been established on heterotic orbifolds explicitely, these findings
might appear contradictory at first sight. Possible inconsistencies are avoided
by reinterpreting a charged twisted state as a second non-universal localized
axion. The mismatch between the charges of the orbifold and blow-up spectra is
resolved by suitable field redefinitions. The anomaly of the field
redefinitions corresponds to the difference of blow-up and heterotic orbifold
anomalies.Comment: 7 pages LaTe
Effect on the electron EDM due to abelian gauginos in SUSY extra U(1) models
The electric dipole moment of an electron (EDME) is investigated in the
supersymmetric extra U(1) models. Neutralino sector is generally extended in
these models and then the neutralino contribution will be important for the
analysis of the EDME. Kinetic term mixings of abelian gauginos are taken into
account in our analysis. Numerical results for the extra U(1) models show that
the EDME can be affected by the extra U(1) in a certain range of soft
supersymmetry breaking parameters even if the extra U(1) gauge boson is heavy.
The EDME may be a clue to find an extended gauge structure in the
supersymmetric models.Comment: 16 pages, latex, 3 figure
Gluino Condensation in Strongly Coupled Heterotic String Theory
Strongly coupled heterotic string theory, compactified to
four dimensions on a large Calabi-Yau manifold , may represent a
viable candidate for the description of low-energy particle phenomenology. In
this regime, heterotic string theory is adequately described by low-energy
-theory on , with the two
's supported at the two boundaries of the world. In this paper we study
the effects of gluino condensation, as a mechanism for supersymmetry breaking
in this -theory regime. We show that when a gluino condensate forms in
-theory, the conditions for unbroken supersymmetry can still be satisfied
locally in the orbifold dimension . Supersymmetry is then
only broken by the global topology of the orbifold dimension, in a mechanism
similar to the Casimir effect. This mechanism leads to a natural hierarchy of
scales, and elucidates some aspects of heterotic string theory that might be
relevant to the stabilization of moduli and the smallness of the cosmological
constant.Comment: 22 pages, harvmac, no figure
Small SUSY phases in string-inspired supergravity
In supersymmetric models, there are new CP violating phases which, if
unsuppressed, would give a too large neutron electric dipole moment. We examine
the possibility of small SUSY phases in string-inspired supergravity models in
which supersymmetry is broken by the auxiliary components of the dilaton and
moduli superfields. It is found that the SUSY phases can be suppressed by a
small factor governing the breakdown of the approximate Peccei Quinn symmetries
nonlinearly realized for the moduli superfields that participate in
supersymmetry breaking. In many cases, the symmetry breaking factors are
exponentially small for moderately large values of the moduli, leading to small
phase values in a natural way.Comment: 15pages, Latex, SNUTP 93-8
Supergravity Inflation Free from Harmful Relics
We present a realistic supergravity inflation model which is free from the
overproduction of potentially dangerous relics in cosmology, namely moduli and
gravitinos which can lead to the inconsistencies with the predictions of baryon
asymmetry and nucleosynthesis. The radiative correction turns out to play a
crucial role in our analysis which raises the mass of supersymmetry breaking
field to intermediate scale. We pay a particular attention to the non-thermal
production of gravitinos using the non-minimal Kahler potential we obtained
from loop correction. This non-thermal gravitino production however is
diminished because of the relatively small scale of inflaton mass and small
amplitudes of hidden sector fields.Comment: 10 pages, revtex, 1 eps figure, references added, conclusion section
expande
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