On the symplectic fillings of standard real projective spaces

We prove, in a geometric way, that the standard contact structure on the real projective space of dimension $2n-1$ is not Liouville fillable for $n\ge 3$ and odd. We also prove that, for all $n$, semipositive fillings of those contact structures are simply connected. Finally we give yet another proof of the Eliashberg-Floer-McDuff theorem on the diffeomorphism type of the symplectically aspherical fillings of the standard contact structure on the $(2n-1)$-dimensional sphere.