Kieran O'Grady Rome I Title: Moduli of double EPW-sexticsAbstract: We study the GIT quotient of the symplectic grassmannian(the symplectic form on \bigwedge^3 {\mathbb C}^6 is given by wedge product). The GIT quotient is a compactification of the moduli space of double EPW-sextics and may be viewed as an analogue of the moduli space of cubic 4-folds. We classify stable points and the components of the GIT-boundary. Since our final goal is to study the period map we compare (semi)stability and the behaviour of periods. |