speaker: Ryotaku Suzuki (Barcelona Univ./Osaka City Univ.)
date/time: 4th June 2019, 16:30-18:00
place: A328
title: Topology-changing horizons at large D as Ricci flows
abstractF
In the dimension higher than four, General Relativity allows 
black hole solutions with a variety of horizon topologies other 
than the sphere. Some of solutions of different topologies 
are conjectured, and also confirmed by numerical works, to 
merge together in the solution space, through a singular 
critical solution in which the horizon has the conical pinch.

In this talk, I will show that a new type of the large D limit 
(large dimension limit) provides an analytic description for 
these merger phases zooming in on the very region in which 
the topology change takes place. It turns out that, in general, 
the geometry close to the pinch is determined by the Ricci 
flow equation. For the simplest case of the merger between 
black strings (BS) and black holes (BH) in the Kaluza-Klein 
spacetime, the Ricci flow equation reduces to the logarithmic 
diffusion equation. I will also demonstrate that this diffusion 
equation actually admits the topology-changing solution 
corresponding to the BS/BH transition in the simple analytic 
form.