614 research outputs found
Constraining heavy dark matter with cosmic-ray antiprotons
Cosmic-ray observations provide a powerful probe of dark matter annihilation
in the Galaxy. In this paper we derive constraints on heavy dark matter from
the recent precise AMS-02 antiproton data. We consider all possible
annihilation channels into pairs of standard model particles. Furthermore, we
interpret our results in the context of minimal dark matter, including
higgsino, wino and quintuplet dark matter. We compare the cosmic-ray antiproton
limits to limits from -ray observations of dwarf spheroidal galaxies
and to limits from -ray and -line observations towards the
Galactic center. While the latter limits are highly dependent on the dark
matter density distribution and only exclude a thermal wino for cuspy profiles,
the cosmic-ray limits are more robust, strongly disfavoring the thermal wino
dark matter scenario even for a conservative estimate of systematic
uncertainties.Comment: 14 pages + references, 5 figures; v2: HESS limits added in Fig. 2,
matches published versio
Probing dark matter annihilation in the Galaxy with antiprotons and gamma rays
A possible hint of dark matter annihilation has been found in Cuoco,
Korsmeier and Kr\"amer (2017) from an analysis of recent cosmic-ray antiproton
data from AMS-02 and taking into account cosmic-ray propagation uncertainties
by fitting at the same time dark matter and propagation parameters. Here, we
extend this analysis to a wider class of annihilation channels. We find
consistent hints of a dark matter signal with an annihilation cross-section
close to the thermal value and with masses in range between 40 and 130 GeV
depending on the annihilation channel. Furthermore, we investigate in how far
the possible signal is compatible with the Galactic center gamma-ray excess and
recent observation of dwarf satellite galaxies by performing a joint global fit
including uncertainties in the dark matter density profile. As an example, we
interpret our results in the framework of the Higgs portal model.Comment: 12 pages + references, 4 figures, v2: References added, minor changes
in presentation, matches journal versio
Effective field theory interpretation of searches for dark matter annihilation in the Sun with the IceCube Neutrino Observatory
We present a model-independent interpretation of searches for dark matter
annihilation in the Sun using an effective field theory approach. We identify a
set of effective operators contributing to spin-dependent scattering of dark
matter with protons in the non-relativistic limit and explore simple new
physics models which would give rise to such operators. Using the limits on the
spin-dependent scattering cross-section set by the IceCube collaboration in
their search for dark matter annihilation in the Sun, we derive limits on
effective couplings and corresponding masses of mediating particles. We show
that the effective field theory interpretation of the IceCube searches provides
constraints on dark matter complementary to those from relic density
observations and searches at the LHC. Finally, we discuss the impact of
astrophysical uncertainties on our results.Comment: 16 pages, 6 figures; Added references in v
A global fit of the -ray galactic center excess within the scalar singlet Higgs portal model
We analyse the excess in the -ray emission from the center of our
galaxy observed by Fermi-LAT in terms of dark matter annihilation within the
scalar Higgs portal model. In particular, we include the astrophysical
uncertainties from the dark matter distribution and allow for unspecified
additional dark matter components. We demonstrate through a detailed numerical
fit that the strength and shape of the -ray spectrum can indeed be
described by the model in various regions of dark matter masses and couplings.
Constraints from invisible Higgs decays, direct dark matter searches, indirect
searches in dwarf galaxies and for -ray lines, and constraints from the
dark matter relic density reduce the parameter space to dark matter masses near
the Higgs resonance. We find two viable regions: one where the Higgs-dark
matter coupling is of , and an additional dark matter
component beyond the scalar WIMP of our model is preferred, and one region
where the Higgs-dark matter coupling may be significantly smaller, but where
the scalar WIMP constitutes a significant fraction or even all of dark matter.
Both viable regions are hard to probe in future direct detection and collider
experiments.Comment: 20 pages + references, 12 figures; v2: minor changes in presentation,
references added, improved scan coverage and updated plots in figs. 6, 8, 9,
10 and 12 accordingly, conclusions unchanged, matches journal versio
Regularity and Symmetry Results for Ground State Solutions of Quasilinear Elliptic Equations
This dissertation deals with boundary value problems similar to the p-Laplace and prescribed mean curvature equation with Dirichlet boundary conditions. The equation is structurally more complicated than the p-Laplace equation and it is elliptic, but not uniformly elliptic.
The main results are:
- Study of the qualitative behaviour of radially symmetric solutions.
- Symmetry of mountain pass solutions using Schwarz symmetrization.
- A decay estimate for the Hoelder norm of the derivatives
Diagrams
a) Topics and Objectives. This research group investigates the history and
theory of thinking with the help of diagrams. Diagrams are conceived as
cognitive instruments which exploit spatial relationships paradigmatically in
order to represent, analyze, and generate knowledge. We use the term "diagram"
in both a narrow and in an extended sense: defined more narrowly, diagrams are
schematic figures such as geometric constructions or chemical structural
formulae; defined in an extended sense, the term may also refer to texts,
charts, mathematical formulae, in short: all types of inscriptions upon a
delimited surface which display diagrammatical aspects. The guiding
presuppositions of our research are: (1) by means of spatial logics and
topological orders, diagrams are preferred forms for representing non-spatial,
theoretical relationships. (2) Diagrams do not display simple ›objects,‹ but
instead relationships within a conceptual or knowledge field. (3) As a
consequence, diagrams not only open up spaces of representation, but also
experimental, explorative, and operational spaces, in many cases involving
abstract, non-sensory, or ideational contents. Diagrams render theories
susceptible to experience in sensory terms. (4) On the whole, the capacity for
graphism may be ranged alongside the capacity for language as a universal
anthropological trait. Against this horizon, our research project – whose
orientation is epistemological and philosophical – pursues two problems. The
first involves the basic contours of a general theory of diagrammatics and –
starting from the ›cartographic impulse‹ embodied in Plato’s parable of the
line and in Ptolemy’s "handbook of geography" – an ›epistemology of the line‹
as a philosophical reconstruction of the implicit and explicit diagrammatical
aspects of philosophical texts. The second problem involves the diagram as a
cognitive artifact which is examined from historical and systematic
perspectives. b) Methods: Philosophical analysis of texts, case studies of
individual thinkers and specific types of diagrams. c) Current state of the
discussion within the research group: Basic concepts related to diagrammatics
have been elaborated, central episodes in the Occidental theory of the diagram
identified and analyzed, and central elements of a general theory of
diagrammatic cognition developed. Planned for the future is on the one hand
deepened work on historical case studies, and on the other the integration of
the hitherto developed modules into a consistent, overarching theory.a) Gegenstände und Ziele. Diese Forschergruppe untersucht Geschichte und
Theorie des Denkens mit Hilfe von Diagrammen. Diagramme werden als kognitive
Instrumente begriffen, die in paradigmatischer Weise Raumrelationen zur
Darstellung, Analyse und Produktion von Wissen nutzen. Wir verwenden den
Begriff »Diagramm« in einem engen und einem erweiterten Sinne: Diagramme im
engeren Sinne sind schematische Figuren wie etwa geometrische Konstruktionen
oder chemische Strukturformeln, im erweiterten Sinne weisen aber auch
Schriften, Tabellen, mathematische Formeln, kurz: alle Arten von Inskriptionen
auf einer begrenzten Fläche, diagrammatische Dimensionen auf. Die leitenden
Annahmen unserer Forschung sind: (1) Diagramme stellen mittels räumlicher
Logiken und topologischer Ordnungen bevorzugt nicht-räumliche, theoretische
Zusammenhänge dar. (2) Sie zeigen dabei nicht einfach ›Gegenstände‹, sondern
Relationen innerhalb von Begriffs- und Wissensfeldern. (3) Dadurch eröffnen
sie nicht nur einen Darstellungsraum, sondern auch einen Raum des
Experimentierens, Explorierens und Operierens mit oftmals abstrakten,
unsinnlichen, ideellen Sachverhalten. Diagramme machen Theorien sinnlich
erfahrbar. (4) Insgesamt ist die Fähigkeit zum Graphismus eine dem
Sprachvermögen durchaus zur Seite zu stellende universelle anthropologische
Auszeichnung. Vor diesem Horizont verfolgt unser epistemologisch-philosophisch
orientiertes Forschungsprojekt zwei Fragen. Erstens: Grundlinien einer
allgemeinen Theorie der Diagrammatik und – ausgehend von einem
›kartographischen Impuls‹ der in Platons Liniengleichnis und in Ptolemaios’
»Handbuch der Geographie« verkörpert ist – eine ›Epistemologie der Linie‹ als
philosophische Rekonstruktion der impliziten und expliziten diagrammatischen
Dimensionen in philosophischen Texten. Zweitens: Diagramme als kognitive
Artefakte in historischer und systematischer Perspektive. b) Methoden.
Philosophische Analyse von Texten, Fallstudien zu einzelnen Denkern und
Diagrammtypen. c) Diskussionsstand in der Forschergruppe. Grundbegriffe der
Diagrammatik wurden erarbeitet, zentrale Episoden abendländischer Theorie des
Diagramms identifiziert und analysiert, zentrale Elemente einer allgemeinen
Theorie diagrammatischer Kognition entwickelt. Für die Zukunft steht
einerseits die vertiefte Arbeit an historischen Fallstudien, andererseits die
Integration der bisherigen Bausteine zu einer konsistenten, übergreifenden
Theorie an
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