# Gravity without averaging

28.10.2021 18:00 – 19:00

Recently it has been shown that JT gravity is dual to a hermitian matrix model. This means that JT gravity is not dual to a single boundary theory, as we would expect from higher dimensional examples of AdS/CFT, but rather to an ensemble of theories. In this talk I will present a gravitational theory that interpolates between JT gravity, where there is an ensemble and a gravity theory with a fixed boundary Hamiltonian, which is more like what occurs in higher dimensions. For this, we consider a matrix integral with the insertion of a Gaussian with variance $\sigma$, centered around a matrix $H_0$. Tightening the Gaussian renders the matrix integral less random, and ultimately it collapses the ensemble to one Hamiltonian $H_0$. This model provides a concrete setup to study factorization, and what the gravity dual of a single member of the ensemble is. We find that as $\sigma$ is decreased, the JT gravity dilaton potential gets modified, and ultimately the gravity theory goes through a series of phase transitions, corresponding to a proliferation of extra macroscopic holes in the spacetime.

### Lieu

Bâtiment: Sciences I

306

### Organisé par

Faculté des sciencesDépartement de physique théorique

### Intervenants

Jorrit Kruthoff, Stanford Universityentrée libre

### Plus d'infos

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