1,985 research outputs found

### CTA in the Context of Searches for Particle Dark Matter - a glimpse

In this contribution, CTAs potential role in detection of particle dark
matter in the context of other detection approaches is briefly discussed for an
audience of gamma-ray astronomers. In particular searches for new particles at
the large hadron collider and detection of dark matter particles in deep
underground detectors are considered. We will focus on Weakly Interacting
Massive Particles (WIMP). Approaches will be compared in terms of (a)
robustness of sensitivity predictions, (b) timeline and (c) reach. The estimate
of the reach will be model-dependent. Given our ignorance about the nature of
dark matter, and the complementarity of detection techniques even within a
given framework (e.g. Supersymmetry), the trivial conclusion is that we might
need all approaches and the most sensitive experiments. Our discussion will be
somewhat more restrictive in order to be able to be more concrete. With the
caveat of incompleteness, under the assumption that the WIMP paradigm describes
nature, CTA is more likely to discover multi-TeV WIMP dark matter, whereas for
lower masses direct detection and LHC has significantly better prospects. We
will illustrate this conclusion with examples from foremost Supersymmetry, but
mention effective field theory or simplified models. We will comment on a few
models predicting high mass WIMPs, in particular 1 TeV higgsino and wino WIMPs,
as well as Minimal Dark Matter and point out the relevance of updated
measurements of the anomalous magnetic moment of the muon for CTAs role in
searches for Supersymmetry.Comment: Invited contribution to 6th International Symposium on High-Energy
Gamma-ray Astronomy (Gamma2016). 9 pages, 5 figure

### Searches for Particle Dark Matter with gamma-rays

In this contribution I review the present status and discuss some prospects
for indirect detection of dark matter with gamma-rays. Thanks to the Fermi
Large Area Telescope, searches in gamma-rays have reached sensitivities that
allow to probe the most interesting parameter space of the weakly interacting
massive particles (WIMP) paradigm. This gain in sensitivity is naturally
accompanied by a number of detection claims or indications, the most recent
being the claim of a line feature at a dark matter particle mass of $\sim$ 130
GeV at the Galactic Centre, a claim which requires confirmation from the
Fermi-LAT collaboration and other experiments, for example HESS II or the
planned Gamma-400 satellite. Predictions for the next generation air Cherenkov
telescope, Cherenkov Telescope Array (CTA), together with forecasts on future
Fermi-LAT constraints arrive at the exciting possibility that the cosmological
benchmark cross-section could be probed from masses of a few GeV to a few TeV.
Consequently, non-detection would pose a challenge to the WIMP paradigm, but
the reached sensitivities also imply that --optimistically-- a detection is in
the cards.Comment: Invited "compact review", 5th International Symposium on High Energy
Gamma-Ray Astronomy (Gamma 2012), Heidelberg, 11 pages, 3 figure

### On Fractional Instanton Numbers in Six Dimensional Heterotic E8 x E8 Orbifolds

We derive the precise relation between level matching condition and
fractional instanton numbers in six dimensional, abelian and supersymmetric
orbifolds of E8 x E8 heterotic string theory. The fractional part of the two E8
instanton numbers is explicitly calculated in terms of the gauge twist. This
relation is then used to show that the classification of these orbifolds can be
given in terms of flat bundles away from the orbifold singularities under the
only constraint that the sum of the fractional parts of the gauge instanton
numbers match the fractional part of the gravitational instanton number locally
at every fixed point. This directly carries over to M-theory on S^1/Z_2Comment: latex2e, 12 pages; reference and comments adde

### Likelihood ratio intervals with Bayesian treatment of uncertainties: coverage, power and combined experiments

In this note we present studies of coverage and power for confidence
intervals for a Poisson process with known background calculated using the
Likelihood ratio (aka Feldman & Cousins) ordering with Bayesian treatment of
uncertainties in nuisance parameters. We consider both the variant where the
Bayesian integration is done in both the numerator and the denominator and the
modification where the integration is done only in the numerator whereas in the
denominator the likelihood is taken at the maximum likelihood estimate of the
parameters. Furthermore we discuss how measurements can be combined in this
framework and give an illustration with limits on the branching ratio of a rare
B-meson decay recently presented by CDF/D0. A set of C++ classes has been
developed which can be used to calculate confidence intervals for single or
combining multiple experiments using the above algorithms and considering a
variety of parameterizations to describe the uncertainties.Comment: 4 pages, 3 figures, to appear in proceedings of PhyStat2005, Oxford,
UK, Sept 2005, Imperial College Pres

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