Group action on instanton bundles over ³

الأصل · EN

Denote by MI(k) the moduli space of k-instanton bundles E of rank 2 on ³=(V) and by Zₖ(E) the scheme of k-jumping lines. We prove that [E]∈ MI(k) is not stable for the action of SL(V) if Zₖ(E)≠. Moreover Sym(E)≥ 1 if length Zₖ(E)≥ 2. We prove also that E is special if and only if Zₖ(E) is a smooth conic. The action of SL(V) on the moduli of special instanton bundles is studied in detail.