26,653 research outputs found
Moduli stabilization and uplifting with dynamically generated F-terms
We use the F-term dynamical supersymmetry breaking models with metastable
vacua in order to uplift the vacuum energy in the KKLT moduli stabilization
scenario. The main advantage compared to earlier proposals is the manifest
supersymmetric treatment and the natural coexistence of a TeV gravitino mass
with a zero cosmological constant. We argue that it is generically difficult to
avoid anti de-Sitter supersymmetric minima, however the tunneling rate from the
metastable vacuum with zero vacuum energy towards them can be very suppressed.
We briefly comment on the properties of the induced soft terms in the
observable sector.Comment: 18 pages, no figures Comments and one reference adde
Different pathways in mechanical unfolding/folding cycle of a single semiflexible polymer
Kinetics of conformational change of a semiflexible polymer under mechanical
external field were investigated with Langevin dynamics simulations. It is
found that a semiflexible polymer exhibits large hysteresis in mechanical
folding/unfolding cycle even with a slow operation, whereas in a flexible
polymer, the hysteresis almost disappears at a sufficiently slow operation.
This suggests that the essential features of the structural transition of a
semiflexible polymer should be interpreted at least on a two-dimensional phase
space. The appearance of such large hysteresis is discussed in relation to
different pathways in the loading and unloading processes. By using a minimal
two-variable model, the hysteresis loop is described in terms of different
pathways on the transition between two stable states.Comment: 19 pages, 5 figure
Light propagation in atomic Mott Insulators
We study radiation-matter interaction in a system of ultracold atoms trapped
in an optical lattice in a Mott insulator phase. We develop a fully general
quantum model, and we perform calculations for a one-dimensional geometry at
normal incidence. Both two- and three-level atomic configurations are
studied. The polariton dispersion and the reflectivity spectra are
characterized in the different regimes, for both semi-infinite and finite-size
geometries. We apply this model to propose a photon energy lifter experiment: a
device which is able to shift the carrier frequency of a slowly travelling
wavepacket without affecting the pulse shape nor its coherence
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