1,515 research outputs found
Trapping black hole remnants
Large extra dimensions lower the Planck scale to values soon accessible. The production of TeV mass black holes at the LHC is one of the most exciting predictions. However, the final phases of the black hole's evaporation are still unknown and there are strong indications that a black hole remnant can be left. Since a certain fraction of such objects would be electrically charged, we argue that they can be trapped. In this paper, we examine the occurrence of such charged black hole remnants. These trapped remnants are of high interest, as they could be used to closely investigate the evaporation characteristics. Due to the absence of background from the collision region and the controlled initial state, the signal would be very clear. This would allow to extract information about the late stages of the evaporation process with high precision
Black Holes at LHC?
Strategies for identifying speculative mini black hole events (due to large
extra dimensions) at future colliders are reviewed. Estimates for production
cross sections, Hawking radiation, di-jet suppression and multi- mono-jet
emission are surveyed. We further report on a class of effective entropy
formulas that could lead to the formation of a final black hole remnant state,
BHR. Such BHRs could be both electrically charged and uncharged. Charged BHRs
should be observable by single stiff charged tracks in the detectors. Collinear
hadronic jets with a large missing transverse momentum are presented as new
observable signal for electrically neutral black holes.Comment: added references to old version, 9 pages, accepted at J. Phys.
Graphs with Plane Outside-Obstacle Representations
An \emph{obstacle representation} of a graph consists of a set of polygonal
obstacles and a distinct point for each vertex such that two points see each
other if and only if the corresponding vertices are adjacent. Obstacle
representations are a recent generalization of classical polygon--vertex
visibility graphs, for which the characterization and recognition problems are
long-standing open questions.
In this paper, we study \emph{plane outside-obstacle representations}, where
all obstacles lie in the unbounded face of the representation and no two
visibility segments cross. We give a combinatorial characterization of the
biconnected graphs that admit such a representation. Based on this
characterization, we present a simple linear-time recognition algorithm for
these graphs. As a side result, we show that the plane vertex--polygon
visibility graphs are exactly the maximal outerplanar graphs and that every
chordal outerplanar graph has an outside-obstacle representation.Comment: 12 pages, 7 figure
Black Hole Remnants at the LHC
Within the scenario of large extra dimensions, the Planck scale is lowered to
values soon accessible. Among the predicted effects, the production of TeV mass
black holes at the {\sc LHC} is one of the most exciting possibilities. Though
the final phases of the black hole's evaporation are still unknown, the
formation of a black hole remnant is a theoretically well motivated
expectation. We analyze the observables emerging from a black hole evaporation
with a remnant instead of a final decay. We show that the formation of a black
hole remnant yields a signature which differs substantially from a final decay.
We find the total transverse momentum of the black hole event to be
significantly dominated by the presence of a remnant mass providing a strong
experimental signature for black hole remnant formation
Zur Kenntnis von Juncus ensifolius WIKSTRĂ–M 1823 : ein Neufund aus dem SĂĽdkreis von OsnabrĂĽck ; mit 1 Tabelle
Juncus ensifolius, eine vor allem im nordwestlichen Amerika beheimatete Binsenart, wird von einem erst seit kurzer Zeit besiedelten RegenrĂĽckhaltebecken in Hagen a. T. W., Landkreis OsnabrĂĽck, beschrieben. Zur Charakterisierung der Einnischung in die heimische Flora sind pflanzensoziologische Aufnahmen beigefĂĽgt
Zur Morphologie, Systematik und Verbreitung des Polyploid komplexes Thlaspi perfoliatum L. [Microthlaspi perfoliatum (L.) F. K. Meyer] in Deutschland
Die Verbreitung unterschiedlicher Cytotypen innerhalb des Thlaspi perfoliatum Polyploidkomplexes in Deutschland wurde untersucht. Morphologische Beschreibungen der Frucht ermöglichen eine weitgehende Trennungder diploiden von den polyploiden Cytotypen. Die systematische Stellung der Sippen innerhalb der Gattung Microthlaspi F.K. Meyer und der Sammelgattung Thlaspi s. I. wird diskutiert, und die Entstehungs- und Verbreitungsgeschichte des Polyploidkomplexes wird erläutert.The distribution of different cytotypes within the Thlaspi perfoliatum polyploid complex has been investigated in Germany. Morphological descriptions of fruit characters enable the recognition and separation of diploids and polyploids. The systematic position of the cytotypes in respect to genus Microthlaspi F.K. Meyer and genus Thlaspi in a broad sense is discussed. Origin and life history of the polyploid complex is outlined
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