11,351 research outputs found
Interacting topological phases in multiband nanowires
We show that semiconductor nanowires coupled to an s-wave superconductor
provide a playground to study effects of interactions between different
topological superconducting phases supporting Majorana zero-energy modes. We
consider quasi-one dimensional system where the topological phases emerge from
different transverse subbands in the nanowire. In a certain parameter space, we
show that there is a multicritical point in the phase diagram where the
low-energy theory is equivalent to the one describing two coupled Majorana
chains. We study effect of interactions as well as symmetry-breaking
perturbations on the topological phase diagram in the vicinity of this
multicritical point. Our results shed light on the stability of the topological
phase around the multicritical point and have important implications for the
experiments on Majorana nanowires.Comment: 8 pages, 2 figures; final version to appear in PR
Interplay of disorder and interaction in Majorana quantum wires
We study the interplay between disorder and interaction in one-dimensional
topological superconductors which carry localized Majorana zero-energy states.
Using Abelian bosonization and the perturbative renormalization group (RG)
approach, we obtain the RG-flow and the associated scaling dimensions of the
parameters and identify the critical points of the low-energy theory. We
predict a quantum phase transition from a topological superconducting phase to
a non-topological localized phase, and obtain the phase boundary between these
two phases as a function of the electron-electron interaction and the disorder
strength in the nanowire. Based on an instanton analysis which incorporates the
effect of disorder, we also identify a large regime of stability of the
Majorana-carrying topological phase in the parameter space of the model.Comment: New version includes a section and an appendix with a detailed study
on the effect of interaction and disorder on the stability of Majorana
end-states. 6 pages, 1 figur
Module extraction via query inseparability in OWL 2 QL
We show that deciding conjunctive query inseparability for OWL 2 QL ontologies is PSpace-hard and in ExpTime. We give polynomial-time (incomplete) algorithms and demonstrate by experiments that they can be used for practical module extraction
Multiscale Analysis in Momentum Space for Quasi-periodic Potential in Dimension Two
We consider a polyharmonic operator H=(-\Delta)^l+V(\x) in dimension two
with , being an integer, and a quasi-periodic potential V(\x).
We prove that the absolutely continuous spectrum of contains a semiaxis and
there is a family of generalized eigenfunctions at every point of this semiaxis
with the following properties. First, the eigenfunctions are close to plane
waves at the high energy region. Second, the isoenergetic
curves in the space of momenta \k corresponding to these eigenfunctions have
a form of slightly distorted circles with holes (Cantor type structure). A new
method of multiscale analysis in the momentum space is developed to prove these
results.Comment: 125 pages, 4 figures. arXiv admin note: incorporates arXiv:1205.118
Dilaton thin-shell wormholes supported by a generalized Chaplygin gas
In this article, we construct spherical thin-shell wormholes with charge in
dilaton gravity. The exotic matter required for the construction is provided by
a generalized Chaplygin gas. We study the stability under perturbations
preserving the symmetry. We find that the increase of the coupling between the
dilaton and the electromagnetic fields reduces the range of the parameters for
which stable configurations are possible.Comment: 14 pages, 6 figures. v3: typos correcte
The investment location decisions in the steel industry
The global dimension of the economy in general and of the steel industry in particular makes the decision regarding the location of new production facilities a challenge for managers. This paper tries to provide tools that make the decision taking process easier. Is assumed that certain tax levy rates are important to this process and they are compared and analyzed. Finally, based on this analysis this paper tries to prioritize some countries in terms of their economic attractiveness in order to identify the most suitable country for placing a steel factory
The investment location decisions in the steel industry
The global dimension of the economy in general and of the steel industry in particular makes the decision regarding the location of new production facilities a challenge for managers. This paper tries to provide tools that make the decision taking process easier. Is assumed that certain tax levy rates are important to this process and they are compared and analyzed. Finally, based on this analysis this paper tries to prioritize some countries in terms of their economic attractiveness in order to identify the most suitable country for placing a steel factory
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