begin{center}(attention : heure inhabituelle / unusual hour)end{center} par I review a description of the moduli space of hypermultiplets appearing in 4d compactifications of type II string theories in terms of N=2 projective superspace. This description can be used to formulate a c-map, which allows to construct a hypermultiplet sigma-model out of the holomorphic prepotential for vector multiplets. I find explicitly the low-energy effective action for the hypermultiplets, including perturbative string corrections, and present some details on the geometry of the moduli space, which can be useful in the quantization of BPS black holes.

Université Montpellier 2