String Theory Seminars - Fall 2006

Eva Silverstein (Stanford University), The Growth of Negativity.

Ilarion Melnikov (University of Chicago), Non-Local Observables in Toric A-Models.

Non-local operators are seldom considered in topological sigma models, as they are not very easy to compute. However, a simple extension of the recently developed methods for treating correlators of local operators in the A-twisted gauged linear sigma model makes these correlators eminently computable. I will review the method, compute some of these non-trivial correlators, and discuss some of their properties.

Robert Karp (Rutgers University), Derived Autoequivalences from String Theory.

Timo Weigand (University of Pennsylvania), D-brane Instanton Effects in 4-Dimensional String Vacua and Their Phenomenological Implications.
[video] [transparencies]

V Parameswaran Nair (City College, CUNY), Comments on Twistor Strings: Old and New.
[transparencies]

Alexander Maloney (Institute for Advanced Study), AdS/CFT and Cosmology.

We consider variants of Anti-de Sitter space, which can be thought of as very simple cosmologies: they are closed, FRW cosmologies with big bang and big crunch singularities. The AdS/CFT correspondence then allows us to address basic puzzles concerning quantum gravity in cosmological settings. A Euclidean version of AdS/CFT turns out to be useful: it gives a precise definition of the Hilbert space of quantum gravity in these cosmologies. It also picks out a special state - analogous to the Hartle-Hawking "no boundary" wave function - for this cosmology, which describes an exactly thermal configuration of particles emerging from the big bang singularity. Correlators of the dual Euclidean CFTs also encode information about the stringy geometry of the big bang/crunch singularities, via a subtle analytic continuation.

Christopher Herzog (University of Washington), Energy Loss of a Heavy Quark from AdS/CFT.

Abhishek Agarwal (City College, CUNY), Aspects of Integrability in N=4 Super Yang-Mills.
[video] [transparencies]