Theory Group Seminar, 19 January 2021

Alex Maloney, McGill University

Gravity from Averaging CFTs

abstract

I will explore the idea that certain theories of gravity in Anti-de
Sitter space are dual to an average over an ensemble of quantum
theories, rather than to a specific quantum theory. I will describe
an average over Narainâ€™s family of two-dimensional conformal field
theories which describe free bosons on a torus, and compute the
partition function using the Siegel-Weil formula. The result takes
the form of a sum over geometries as one would expect in a theory of
gravity. But the gravitational theory looks more like a Chern-Simons
theory than like Einstein gravity.