A "buffet dinatoire" will be organized on Wednesday 1st Oct evening between 19h30 and 22h in the Esclangon cellars in the Jussieu campus basement
https://sciences.sorbonne-universite.fr/faculte/location-despaces/hall-et-caves-esclangon
They are located directly under the Esclangon building, at 4 place Jussieu, 75005 Paris, on the right as you enter the campus.