38 research outputs found
Influence of laser power density on the mesostructure of thermoplastic composite preforms manufactured by Automated Fibre Placement
Moduli in Exceptional SUSY Gauge Theories
The low energy structures of N=1 supersymmetric models with E_6, F_4 and E_7
gauge groups and fundamental irrep matter contents are studied herein. We
identify sets of gauge invariant composites which label all flat directions in
the confining/Higgs phases of these theories. The impossibility of mapping
several of these primary operators rules out previously conjectured exceptional
self duals reported in the literature.Comment: 20 pages, harvmac and tables macro
On Supersymmetric D7-branes in the Warped Deformed Conifold
We study the supersymmetric properties of D7-branes in the warped deformed
conifold. We consider the -symmetry conditions on D7-branes in this
specific warped background, taking into account the background NS-NS 2-form
flux. While any holomorphic embedding defines a supersymmetric D7-brane in the
absence of background H-flux, most of the D7-brane embeddings considered in the
literature do not preserve supersymmetry for the warped deformed conifold
without also including brane worldvolume flux. For the simplest such embedding,
we construct numerically the worldvolume fluxnecessary to restore
supersymmetry. We also comment on the dual field theory descriptions in terms
of cascading N=1 supersymmetric gauge theories with flavors. Finally, we
discuss some possible applications of our results to moduli stabilization and
vacuum energy uplifting, gauge/gravity duality, and string inflationary model
building.Comment: 37 pages, 2 figures, v3:many clarifications and improvements to susy
restoring flu
Cosmological Perturbations in a Big Crunch/Big Bang Space-time
A prescription is developed for matching general relativistic perturbations
across singularities of the type encountered in the ekpyrotic and cyclic
scenarios i.e. a collision between orbifold planes. We show that there exists a
gauge in which the evolution of perturbations is locally identical to that in a
model space-time (compactified Milne mod Z_2) where the matching of modes
across the singularity can be treated using a prescription previously
introduced by two of us. Using this approach, we show that long wavelength,
scale-invariant, growing-mode perturbations in the incoming state pass through
the collision and become scale-invariant growing-mode perturbations in the
expanding hot big bang phase.Comment: 47 pages, 4 figure
Sparticle Spectrum of Large Volume Compactification
We examine the large volume compactification of Type IIB string theory or its
F theory limit and the associated supersymmetry breakdown and soft terms. It is
crucial to incorporate the loop-induced moduli mixing, originating from
radiative corrections to the Kahler potential. We show that in the presence of
moduli mixing, soft scalar masses generically receive a D-term contribution of
the order of the gravitino mass m_{3/2} when the visible sector cycle is
stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while
the moduli-mediated gaugino masses and A-parameters tend to be of the order of
m_{3/2}/8pi^2. It is noticed also that a too large moduli mixing can
destabilize the large volume solution by making it a saddle point.Comment: 29 page