Unless otherwise stated, seminars
will take place in Seminar Room of the
ICMS
at
the University of Edinburgh.

Please contact the organisers Charles
Strickland-Constable (UoE) or Lotte
Hollands (HW)
with any questions regarding the seminars.

Wednesday,
9 May 2018

1 George Square (Neuroscience) G.8 Gaddum LT

14:30

Alberto Zaffaroni
(Milano-Bicocca)

One of the great success of string theory is the microscopical explanation of the entropy of a class of asymptotically flat black holes.Much less is known about asymptotically AdS black holes in four dimensions or higher. In this talk I explain how to derive the entropy of a class of asymptotically AdS supersymmetric black holes in four dimensions using holography and localisation, a technique to evaluate exact quantities in supersymmetric QFT. I also discuss what is known in five and higher dimensions.

16:00

Lorant Szegedy
(DESY)

We present a state-sum construction of TFTs on r-spin surfaces which
uses a combinatorial model of r-spin structures. We give an example of
such a TFT which computes the Arf invariant for r even. We use the
combinatorial model and this TFT to calculate diffeomorphism classes of
r-spin surfaces with parametrized boundary.

Wednesday,
23 May 2018

1 George Square (Neuroscience) G.8 Gaddum LT

13:00

Lorenzo Foscolo
(Heriot-Watt)

I will introduce basic facts about G2-manifolds (G2-structures, Hitchin’s volume functional) in the special case where the G2-metric admits an isometric action of a compact Lie group with generic orbits of codimension 1. I will then discuss the classical cohomogeneity one examples of complete G2-manifolds found by Bryant–Salamon in 1989. As a warm-up for the seminar talk, I will also review the construction of 4-dimensional ALE and ALF hyperkähler metrics via the Gibbons-Hawking Ansatz.

14:30

Lorenzo Foscolo
(Heriot-Watt)

In the early 2000’s Atiyah–Maldacena–Vafa and Acharya proposed an explanation of the large N duality between Type IIA theory with D6 branes/RR fluxes on the deformed/resolved conifold as a geometric transition in G2-geometry, the so-called G2-flop. In recent joint work with Mark Haskins and Johannes Nordström, we constructed many complete and incomplete G2-metrics with interesting prescribed asymptotic geometry and/or singular behaviour. In particular, we produced infinitely many new asymptotically conical G2-metrics (only three such metrics were previously known) and the first known example of a G2-metric that has an isolated conical singularity, but is otherwise complete (and is not a cone). Our examples provide a metric version of the G2-flop and infinitely many new geometric transitions in G2-geometry.

16:00

Veronika Breunhoelder
(UoE)

The classification of black hole solutions is a problem of central importance in general relativity. While in four dimensional Einstein-Maxwell theory this question has been answered under some assumptions (any asymptotically flat stationary spacetime must be a Kerr-Newman solution), for higher-dimensional general relativity an analogous classification of equilibrium states constitutes a major open problem. In this talk I will present some recent work in which we determine all asymptotically flat, supersymmetric and biaxisymmetric soliton and black hole solutions to five dimensional minimal supergravity by combining local constraints from supersymmetry with global constraints for stationary and biaxisymmetric spacetimes. We find that horizon topologies must be one of S^3, S^1×S^2 or a lens space L(p,1), with a large moduli space of black hole spacetimes for each of these allowed horizon topologies. In the absence of a black hole we obtain a classification of the known “bubbling” soliton spacetimes.