This week


Extended Riemannian Geometry and Double Field Theory

Regular Seminar Christian Samann (Heriot Watt University)

13:15 KCL
room G01 Norfolk Building

I present an extended version of Riemannian geometry suitable for the description of current formulations of double field theory (DFT). This framework is based on graded manifolds and it yields extended notions of symmetries, dynamical data and constraints. In special cases, we recover general relativity with and without 1-, 2- and 3-form gauge potentials as well as DFT. We believe that our extended Riemannian geometry helps to clarify the role of various constructions in DFT. For example, it leads to a covariant form of the strong section condition. Furthermore, it should provide a useful step towards global and coordinate invariant descriptions of T- and U-duality invariant field theories.

Yang-Baxter strings, twists, and AdS/CFT

Regular Seminar Stijn van Tongeren (Humboldt U.)

14:00 IC
room H503

The appearance of integrability in the duality between the AdS5xS5 string and planar maximally supersymmetric Yang-Mills theory gives rise to many insightful results. Various deformations of this AdS/CFT dual pair are known to also be integrable, prompting the question how far the power of integrability extends in this setting. In recent years there has been a lot of progress in answering this question. Rather than trying to demonstrate integrability in known AdS/CFT dual pairs, efforts instead focused on finding manifestly integrability preserving deformations of the AdS5xS5 string. While constructed to preserve integrability, the resulting so-called Yang-Baxter sigma models are, however, not guaranteed to describe strings, or have an AdS/CFT interpretation. The former of these points has since been addressed and turns out to be closely related to (nonabelian) T duality, and we now understand which of these models continue to describe strings. The goal of my talk is to address the latter point, regarding the AdS/CFT interpretation of these models. I will use symmetry considerations to give a unified AdS/CFT picture for these Yang-Baxter strings as duals to various noncommutative deformations of supersymmetric Yang-Mills theory. My general conjecture matches many known dualities, and I will briefly discuss nontrivial tests in various new cases, in the form of brane constructions indicating the desired dualities.


What is Dark Matter?

Regular Seminar Tommi Tenkanen (QMUL)

14:00 QMW
room G.O. Jones 610

The nature of the unknown non-baryonic energy density component whose abundance is known to exceed the amount of ordinary, visible matter by a factor of five, that of Dark Matter (DM), is one of the greatest open problems in cosmology. In this talk I will briefly review the evidence and searches for DM, present an overview of candidates including the standard WIMP paradigm, and discuss some recently proposed alternatives for WIMPs and how to test them.