10,752 research outputs found
Jet Formation in the magnetospheres of supermassive black holes: analytic solutions describing energy loss through Blandford-Znajek processes
In this paper, we provide exact solutions for the extraction of energy from a
rotating black hole via both the electromagnetic Poynting flux and matter
currents. By appropriate choice of a radially independent poloidal function
, we find solutions where the dominant outward energy flux is
along the polar axis, consistent with a jet-like collimated outflow, but also
with a weaker flux of energy along the equatorial plane. Unlike all the
previously obtained solutions (Blandford & Znajek (1977), Menon & Dermer
(2005)), the magnetosphere is free of magnetic monopoles everywhere
Natural Supersymmetry and Implications for Higgs physics
We re-analyze the LHC bounds on light third generation squarks in Natural
Supersymmetry, where the sparticles have masses inversely proportional to their
leading-log contributions to the electroweak symmetry breaking scale. Higgsinos
are the lightest supersymmetric particles; top and bottom squarks are the
next-to-lightest sparticles that decay into both neutral and charged Higgsinos
with well-defined branching ratios determined by Yukawa couplings and
kinematics. The Higgsinos are nearly degenerate in mass, once the bino and wino
masses are taken to their natural (heavy) values. We consider three scenarios
for the stop and sbottom masses: (I) is light, (II)
and are light, and (III) , , and
are light. Dedicated stop searches are currently sensitive to
Scenarios II and III, but not Scenario I. Sbottom-motivated searches () impact both squark flavors due to \tilde{t} \ra b \charp_1 as well
as \tilde{b} \ra b \neut_{1,2}, constraining Scenarios I and III with
somewhat weaker constraints on Scenario II. The totality of these searches
yield relatively strong constraints on Natural Supersymmetry. Two regions that
remain are: (1) the "compressed wedge", where , and (2) the "kinematic limit" region, where
m_{\tilde{q}} \gsim 600-750 GeV, at the kinematic limit of the LHC searches.
We calculate the correlated predictions for Higgs physics, demonstrating that
these regions lead to distinct predictions for the lightest Higgs couplings
that are separable with \simeq 10% measurements. We show that these
conclusions remain largely unchanged once the MSSM is extended to the NMSSM in
order to naturally obtain a large enough mass for the lightest Higgs boson
consistent with LHC data.Comment: 18 pages, 8 figure
KBGIS-2: A knowledge-based geographic information system
The architecture and working of a recently implemented knowledge-based geographic information system (KBGIS-2) that was designed to satisfy several general criteria for the geographic information system are described. The system has four major functions that include query-answering, learning, and editing. The main query finds constrained locations for spatial objects that are describable in a predicate-calculus based spatial objects language. The main search procedures include a family of constraint-satisfaction procedures that use a spatial object knowledge base to search efficiently for complex spatial objects in large, multilayered spatial data bases. These data bases are represented in quadtree form. The search strategy is designed to reduce the computational cost of search in the average case. The learning capabilities of the system include the addition of new locations of complex spatial objects to the knowledge base as queries are answered, and the ability to learn inductively definitions of new spatial objects from examples. The new definitions are added to the knowledge base by the system. The system is currently performing all its designated tasks successfully, although currently implemented on inadequate hardware. Future reports will detail the performance characteristics of the system, and various new extensions are planned in order to enhance the power of KBGIS-2
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