Aspects of perturbative quantum field theory on non-commutative spaces

In this contribution to the proceedings of the Corfu Summer Institute 2015, I give an overview over quantum field theories on non-commutative Moyal space and renormalization. In particular, I review the new features and challenges one faces when constructing various scalar, fermionic and gauge field theories on Moyal space, and especially how the UV/IR mixing problem was solved for certain models. Finally, I outline more recent progress in constructing a renormalizable gauge field model on non-commutative space, and how one might attempt to prove renormalizability of such a model using a generalized renormalization scheme adapted to the non-commutative (and hence non-local) setting.Comment: 19 pages, 4 figures; invited talk presented at the "Workshop on Noncommutative Field Theory and Gravity" in Corfu, Greece, 21-27 September 2015, to appear in the proceedings of the Corfu Summer Institute 2015 "School and Workshops on Elementary Particle Physics and Gravity

No. 13: The Growth of Food Banking in Cities of the Global South

As the number and size of food banks increase globally, it is critical to research how food banks fit into existing food systems and their role in reducing food insecurity and food waste. After examining the political ecology of urban food waste in food systems, this discussion paper examines the globalization of food banking and its growth in the Global South. Through a case study of FoodForward SA, it critically analyzes the roles that urban food banks play in cities of the Global South. Since many countries in the South have both the highest levels of food insecurity and the weakest infrastructure, it is in these high-need locations that food banks may struggle to operate effectively. The paper finds that while food banks may improve the efficiency of food redistribution systems, it is unclear whether they reduce food insecurity or food waste in the long term. Also, many food banks suffer institutional crises related to lack of funding, interference by the state or private sector, and inappropriate placement in many parts of the Global South

Curvature and Gravity Actions for Matrix Models II: the case of general Poisson structure

We study the geometrical meaning of higher-order terms in matrix models of Yang-Mills type in the semi-classical limit, generalizing recent results arXiv:1003.4132 to the case of 4-dimensional space-time geometries with general Poisson structure. Such terms are expected to arise e.g. upon quantization of the IKKT-type models. We identify terms which depend only on the intrinsic geometry and curvature, including modified versions of the Einstein-Hilbert action, as well as terms which depend on the extrinsic curvature. Furthermore, a mechanism is found which implies that the effective metric G on the space-time brane M \subset R^D "almost" coincides with the induced metric g. Deviations from G=g are suppressed, and characterized by the would-be U(1) gauge field.Comment: 29 pages; v2 minor updat