24,610 research outputs found
Can we discover a light singlet-like NMSSM Higgs boson at the LHC?
In the next-to minimal supersymmetric standard model (NMSSM) one additional
singlet-like Higgs boson with small couplings to standard model (SM) particles
is introduced. Although the mass can be well below the discovered 125 GeV Higgs
boson mass its small couplings may make a discovery at the LHC difficult. We
use a novel scanning technique to efficiently scan the whole parameter space
and determine the range of cross sections and branching ratios for the light
singlet-like Higgs boson below 125 GeV. This allows to determine the
perspectives for the future discovery potential at the LHC. Specific LHC
benchmark points are selected representing the salient NMSSM features.Comment: 22 pages, 5 figures, this version is accepted by PLB after minor
modification
Distributed multilevel optimization for complex structures
Optimization problems concerning complex structures with many design variables may entail an unacceptable computational cost. This problem can be reduced considerably with a multilevel approach: A structure consisting of several components is optimized as a whole (global) as well as on the component level. In this paper, an optimization method is discussed with applications in the assessment of the impact of new design considerations in the development of a structure. A strategy based on fully stressed design is applied for optimization problems in linear statics. A global model is used to calculate the interactions (e.g., loads) for each of the components. These components are then optimized using the prescribed interactions, followed by a new global calculation to update the interactions. Mixed discrete and continuous design variables as well as different design configurations are possible. An application of this strategy is presented in the form of the full optimization of a vertical tail plane center box of a generic large passenger aircraft. In linear dynamics, the parametrization of the component interactions is problematic due to the frequency dependence. Hence, a modified method is presented in which the speed of component mode synthesis is used to avoid this parametrization. This method is applied to a simple test case that originates from noise control. \u
Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective
We present a detailed analysis of the critical behavior close to the
Mott-Anderson transition. Our findings are based on a combination of numerical
and analytical results obtained within the framework of Typical-Medium Theory
(TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT)
capable of incorporating Anderson localization effects. By making use of
previous scaling studies of Anderson impurity models close to the
metal-insulator transition, we solve this problem analytically and reveal the
dependence of the critical behavior on the particle-hole symmetry. Our main
result is that, for sufficiently strong disorder, the Mott-Anderson transition
is characterized by a precisely defined two-fluid behavior, in which only a
fraction of the electrons undergo a "site selective" Mott localization; the
rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in
Phys. Rev. Let
On a novel approach for optimizing composite materials panel using surrogate models
This paper describes an optimization procedure to design thermoplastic composite panels under axial compressive load conditions. Minimum weight is the goal. The panel design is subject to buckling constraints. The presence of the bending-twisting coupling and of particular boundary conditions does not allow an analytical solution for the critical buckling load. Surrogate models are used to approximate the buckling response of the plate in a fast and reliable way. Therefore, two surrogate models are compared to study their effectiveness in composite optimization. The first one is a linear approximation based on the buckling constitutive equation. The second consists in the application of the Kriging surrogate. Constraints given from practical blending rules are also introduced in the optimization. Discrete values of ply thicknesses is a requirement. An ad-hoc discrete optimization strategy is developed, which enables to handle discrete variables
The entropy of a hole in spacetime
We compute the gravitational entropy of 'spherical Rindler space', a
time-dependent, spherically symmetric generalization of ordinary Rindler space,
defined with reference to a family of observers traveling along non-parallel,
accelerated trajectories. All these observers are causally disconnected from a
spherical region H (a 'hole') located at the origin of Minkowski space. The
entropy evaluates to S = A/4G, where A is the area of the spherical
acceleration horizon, which coincides with the boundary of H. We propose that S
is the entropy of entanglement between quantum gravitational degrees of freedom
supporting the interior and the exterior of the sphere H.Comment: 9 pages, 1 figure; v2: published version including updated reference
Entwinement and the emergence of spacetime
It is conventional to study the entanglement between spatial regions of a
quantum field theory. However, in some systems entanglement can be dominated by
"internal", possibly gauged, degrees of freedom that are not spatially
organized, and that can give rise to gaps smaller than the inverse size of the
system. In a holographic context, such small gaps are associated to the
appearance of horizons and singularities in the dual spacetime. Here, we
propose a concept of entwinement, which is intended to capture this fine
structure of the wavefunction. Holographically, entwinement probes the
entanglement shadow -- the region of spacetime not probed by the minimal
surfaces that compute spatial entanglement in the dual field theory. We
consider the simplest example of this scenario -- a 2d conformal field theory
(CFT) that is dual to a conical defect in AdS3 space. Following our previous
work, we show that spatial entanglement in the CFT reproduces spacetime
geometry up to a finite distance from the conical defect. We then show that the
interior geometry up to the defect can be reconstructed from entwinement that
is sensitive to the discretely gauged, fractionated degrees of freedom of the
CFT. Entwinement in the CFT is related to non-minimal geodesics in the conical
defect geometry, suggesting a potential quantum information theoretic meaning
for these objects in a holographic context. These results may be relevant for
the reconstruction of black hole interiors from a dual field theory.Comment: v2: Sec. 4.3 amende
Perspectives of direct Detection of supersymmetric Dark Matter in the NMSSM
In the Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM) the lightest
supersymmetric particle (LSP) is a candidate for the dark matter (DM) in the
universe. It is a mixture from the various gauginos and Higgsinos and can be
bino-, Higgsino- or singlino-dominated. Singlino-dominated LSPs can have very
low cross sections below the neutrino background from coherent neutrino
scattering which is limiting the sensitivity of future direct DM search
experiments. However, previous studies suggested that the combination of both,
the spin-dependent (SD) and spin-independent (SI) searches are sensitive in
complementary regions of parameter space, so considering both searches will
allow to explore practically the whole parameter space of the NMSSM. In this
letter, the different scenarios are investigated with a new scanning technique,
which reveals that significant regions of the NMSSM parameter space cannot be
explored, even if one considers both, SI and SD, searches.Comment: 22 pages, 3 figures, this version is accepted by PLB after minor
modification
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