435 research outputs found
The 130 GeV Fingerprint of Right-Handed Neutrino Dark Matter
Recently, an interesting indication for a dark matter signal in the form of a
narrow line, or maybe two lines and/or an internal bremsstrahlung feature, has
been found in data from the Fermi-LAT satellite detector. As recent analyses
have also shown that there is little sign of extra contributions to continuum
photons, it is natural to investigate leptophilic interacting massive particle
(LIMP) models. We show that a model of radiatively generated neutrino masses
may have the properties needed to explain the Fermi-LAT structure around 130
GeV. This model was proposed some 10 years ago, and predicted a clearly
observable -ray signal in the Fermi-LAT (then GLAST) detector. Here, we
update and improve that analysis, and show as an example that a right-handed
neutrino of mass 135 GeV should give rise to three conspicuous effects: a broad
internal bremsstrahlung bump with maximum around 120 GeV, a 2 line
around 135 GeV, and a line at 119.6 GeV (neglected in the previous
work). These features together give a good fit to the 130 GeV structure, given
the present energy resolution of the Fermi-LAT data. An attractive feature of
the model is that the particle physics properties are essentially fixed, when
relic density and mass of the right-handed neutrino dark matter particle have
been set. Puzzling features of the data at present are a slight displacement of
the signal from the galactic center, and a needed boost factor of order 5-15.
This presents a challenge for numerical simulations including both baryons and
dark matter on scales of 100 pc, and perhaps a need to go beyond the simplest
halo models. With upcoming data, the double-peak structure with the two lines
and the internal bremsstrahlung feature should be seen, if this model is
correct. With the satellite GAMMA-400, a striking fingerprint of this dark
matter candidate should then appear.Comment: 7 pages, 3 figure
Degrees of democraticity
People have tended to load their different conceptions of democracy with their own political ideals; in this paper it is argued that normative and definitional questions should rather be separated, so that political philosophers and political scientists may adopt the same concept of democracy, even if they disagree normatively or politically. Moreover, it is argued that we should replace an absolute notion of democracy by a relativized notion, which allows for different degrees of democraticity. This facilitates the separation of normative and conceptual issues and it is convenient in contexts in which “democratic deficits” are discussed – as e.g. when democracy is to be implemented on a supranational level. Moreover, it has the consequence that democratic deficits are not necessarily bad
Fundamentals of organic agriculture
Organic agriculture can be traced back to the early 20th century, initiated by the Austrian spiritual philosopher Rudolf Steiner. It was later diversified by a number of key people, and more recent versions are guided by principles issued by the International Federation of Organic Agricultural Movements (IFOAM), founded in 1972. Organic practices were built upon the life philosophies and convictions of the founders regarding how to perceive nature. Today, those original views and ideas are considered as history. However, to understand the principles and opinions of modern organic agriculture, such as the exclusion of water-soluble inorganic fertilisers, we analysed the original ideas and arguments of the founders, who shared the common principle of relying on natural processes and methods, seen as a prerequisite for human health. For example, the British agriculturalist Sir Albert Howard, who together with Lady Eve Balfour founded the British Soil Association, claimed that healthy soils are the basis for human health on earth. In their view, healthy soils could only be obtained if the organic matter content was increased or at least maintained. Later, the German physician and microbiologist Hans-Peter Rusch together with the Swiss biologists Hans and Maria Müller, focused on applying natural principles in agriculture, driven by the conviction that nature is our master and always superior. Even though these early ideas have been abandoned or modified in modern organic agriculture, the principle of the founders regarding exclusion of synthetic compounds (fertilisers and pesticides) is still the main driver for choosing crops and pest control methods
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