noindent “Integrability meeting ENS/IPhT'' par By recasting 4 point function by the usual confomal block expansion in terms of structure constants, we initiate the study of four-point functions of large BPS operators at any value of the coupling. We use the hexagon formalism to compute the structure constants. By using the nested Bethe ansatz, we can compute the matrix part of the hexagon form factor for higher rank subgroups of psu$(2,2 mid 4)$. (IPhT organizer: Didina Serban)

LPTENS