(String Journal Club) Lorentzian path integrals and complex saddles of the gravitational partition function
ABSTRACT
In this talk I will review recent work which aims to systematically determine the correct contour of integration for the gravitational partition function. I will begin with a discussion of the work of Marolf, which circumvents the well-known “conformal factor problem” of Euclidean quantum gravity by rewriting the partition function as an integral transform of a Lorentzian path integral over real metrics with conical singularities. I will then give an introduction to the technique of Picard-Lefschetz theory for determining which saddles contribute to the partition function, illustrating the technique via the example of Schwarzchild-AdS black holes. Time permitting, I will comment on the relation between these techniques and the KSW criterion discussed in recent journal clubs.
