# Looking for a bulk point

- Institution: CERN
- Department: TH String Theory Seminar
- Speaker: David Simmons-Duffin
- Year: 2015
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3004332)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

We consider Lorentzian correlators of local operators. In perturbation theory, singularities occur when we can draw a position-space Landau diagram with null lines. In theories with gravity duals, we can also draw Landau diagrams in the bulk. We argue that certain singularities can arise only from bulk diagrams, not from boundary diagrams. As has been previously observed, these singularities are a clear diagnostic of bulk locality. We analyze some properties of these perturbative singularities and discuss their relation to the OPE and the dimensions of double-trace operators. In the exact nonperturbative theory, we expect no singularity at these locations. We prove this statement in 1+1 dimensions by CFT methods.

(Based on 1509.03612 with Maldacena and Zhoboedov). NB: This seminar will be via videolink. Notice the unusual time. .

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## Lectures

1. [Looking for a bulk point](https://invisiblenetwork.ai/learn/cern/3004332/31da4c0f9eb1), 1 h 32 min (CERN's player)