The restricted Siegel disc as coadjoint orbit (Q6611815)

The restricted Siegel disc is a homogeneous space which contains the image of the connected component \(T_0(1)\) of the universal Teichmüller space via the period mapping. The authors show that the restricted Siegel disc is symplectomorphic to a one-parameter family of coadjoint orbits of the universal central extension of the restricted symplectic linear group. At the same time, they show that the restricted Siegel disc is an affine coadjoint orbit of the restricted symplectic group with cocycle given by the Schwinger term.\N\NFor the entire collection see [Zbl 1544.53003].