Stringy Origin of Discrete R-symmetries

Discrete symmetries play a crucial role in particle physics. They appear abundantly in string model constructions. We focus here on the case of discrete $R$-symmetries which are intrinsically connected to the Lorentz group in extra dimensions and the appearance of $N$-extended supersymmetry. In that sense, discrete $R$-symmetries can be understood as "fractionally" extended supersymmetry. These symmetries reveal insight about the location of fields in extra dimensions (in particular the Higgs boson). Applications can be found in the solution of the $\mu$-problem, suppression of proton decay and the structure of the soft terms of broken supersymmetry.Comment: Proceedings of the Corfu Summer Institute 2016 "School and Workshops on Elementary Particle Physics and Gravity",31 August - 23 September, 2016, Corfu, Greec

Ethnological approach of terrace farming

The vast distribution of terraces in the geographical Sudan zone of West Africa leads to the question why and under which conditions an agrarian society might apply this particular form of farming. From an anthropologist's point of view it is essential to understand why farmers practise this form of farming and therefore try to explain the reason for it. The best way to gain insight is the description of terrace farming and when taking a closer look, we realize that farming is nowhere only an isolated agricultural activity

Triggering at High Luminosity Colliders

This article discusses the techniques used to select online promising events at high energy and high luminosity colliders. After a brief introduction, explaining some general aspects of triggering, the more specific implementation options for well established machines like the Tevatron and Large Hadron Collider are presented. An outlook on what difficulties need to be met is given when designing trigger systems at the Super Large Hadron Collider, or at the International Linear ColliderComment: Accepted for publication in New Journal of Physic

Städtische Lebenswelten in Bewegung: In Afrika und darüber hinaus

Although throughout the history of anthropology the ethnography of urban societies was never an important topic, investigations on cities in Africa contributed to the early theoretical development of urban studies in social sciences. As the ethnography of rural migrants in towns made clear, cultural diversity and creativity are foundational and permanent elements of urban cultures in Africa (and beyond). Currently, two new aspects complement these insights: 1) Different forms of mobility have received a new awareness through the concept of transnationalism. They are much more complex, including not only rural–urban migration, but also urban–urban migration, and migrations with a destination beyond the continent. 2) Urban life-worlds also include the appropriation of globally circulating images and lifestyles, which contribute substantially to the current cultural dynamics of cities in Africa. These two aspects are the reasons for the high complexity of urban contexts in Africa. Therefore, whether it is still appropriate to speak about the “locality” of these life-worlds has become questionable. At the same time, these new aspects explain the self-consciousness of members of urban cultures in Africa. They contribute to the expansive character of these societies and to the impression that cities in Africa host the most innovative and creative societies worldwide.Auch wenn die Ethnographie städtischer Gesellschaften in der Geschichte der Ethnologie nie eine große Rolle gespielt hat, leisteten doch Untersuchungen zu urbanen Lebenswelten in Afrika einen wichtigen Beitrag zur frühen theoretischen Entwicklung sozialwissenschaftlicher Stadtforschung. Wie die Ethnographie von Migranten aus ländlichen Räumen in afrikanischen Städten schon damals deutlich machte, sind kulturelle Diversität und Kreativität grundlegende und dauerhafte Elemente urbaner Kultur in Afrika (und weltweit). In letzter Zeit haben zwei wichtige Aspekte diese frühen Einsichten ergänzt: 1) Verschiedene Formen der Mobilität haben durch das Konzept der Transnationalität neue Relevanz gewonnen. 2) Zu urbanen Lebenswelten gehört auch die aktive Aneignung global zirkulierender Bilder und Lebensstile; sie trägt wesentlich zur kulturellen Dynamik afrikanischer Städte bei. Beide Aspekte sind ursächlich für die außerordentliche Komplexität heutiger urbaner Lebenswelten in Afrika. Daher steht infrage, ob es noch angemessen ist, von der „Lokalität“ dieser Lebenswelten zu sprechen. Zugleich erklären diese Aspekte das Selbstbewusstsein der Angehörigen urbaner Gesellschaften in Afrika. Sie tragen zum expansiven Charakter dieser Gesellschaften bei sowie zu dem Eindruck, städtische Gesellschaften in Afrika gehörten zu den innovativsten und kreativsten weltweit