Semi-classical BMS$_3$ blocks and flat holography

Understand

We present the construction of BMS$_3$ blocks in a two-dimensional field theory and compare the results with holographic computations involving probe particles propagating in flat space cosmologies.

• On the field theory side, we generalize the monodromy method used in the context of AdS/CFT to theories with BMS symmetry.
• On the bulk side we consider geodesic Feynman diagrams, recently introduced in [arXiv:1712.07131], evaluated in locally flat geometries generated by backreaction of heavy BMS primary operators.
• We comment on the implications of these results for the eigenstate thermalization hypothesis in flat holography.