21,266 research outputs found
Plane Formation by Synchronous Mobile Robots in the Three Dimensional Euclidean Space
Creating a swarm of mobile computing entities frequently called robots,
agents or sensor nodes, with self-organization ability is a contemporary
challenge in distributed computing. Motivated by this, we investigate the plane
formation problem that requires a swarm of robots moving in the three
dimensional Euclidean space to land on a common plane. The robots are fully
synchronous and endowed with visual perception. But they do not have
identifiers, nor access to the global coordinate system, nor any means of
explicit communication with each other. Though there are plenty of results on
the agreement problem for robots in the two dimensional plane, for example, the
point formation problem, the pattern formation problem, and so on, this is the
first result for robots in the three dimensional space. This paper presents a
necessary and sufficient condition for fully-synchronous robots to solve the
plane formation problem that does not depend on obliviousness i.e., the
availability of local memory at robots. An implication of the result is
somewhat counter-intuitive: The robots cannot form a plane from most of the
semi-regular polyhedra, while they can form a plane from every regular
polyhedron (except a regular icosahedron), whose symmetry is usually considered
to be higher than any semi-regular polyhedrdon
Comment on "Efimov States and their Fano Resonances in a Neutron-Rich Nucleus"
By introducing a mass asymmetry in a non-Borromean three-body system, without
changing the energy relations, the virtual state pole cannot move from the
negative real axis of the complex energy plane (with nonzero width) and become
a resonance, because the analytical structure of the unitarity cuts remains the
same.Comment: To be published in PR
Radii in weakly-bound light halo nuclei
A systematic study of the root-mean-square distance between the constituents
of weakly-bound nuclei consisting of two halo neutrons and a core is performed
using a renormalized zero-range model. The radii are obtained from a universal
scaling function that depends on the mass ratio of the neutron and the core, as
well as on the nature of the subsystems, bound or virtual. Our calculations are
qualitatively consistent with recent data for the neutron-neutron
root-mean-square distance in the halo of Li and Be nuclei
Supersymmetric Heavy Higgses at e^+e^- Linear Collider and Dark-Matter Physics
We consider the capability of the e^+e^- linear collider (which is recently
called as the International Linear Collider, or ILC) for studying the
properties of the heavy Higgs bosons in the supersymmetric standard model. We
pay special attention to the large \tan\beta region which is motivated, in
particular, by explaining the dark-matter density of the universe (i.e.,
so-called ``rapid-annihilation funnels''). We perform a systematic analysis to
estimate expected uncertainties in the masses and widths of the heavy Higgs
bosons assuming an energy and integrated luminosity of \sqrt{s}=1 TeV and L=1
ab^{-1}. We also discuss its implication to the reconstruction of the
dark-matter density of the universe.Comment: 28 pages, 13 figures, version to appear in PR
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