Torsion free instanton sheaves on the blow-up of ${\mathbb{P}}^n$ at a point

Abstract

We define the analogue of instanton sheaves on the blow-up $\widetilde{{\mathbb{P}}^n}$ of the $n-$dimensional projective space at a point. We choose appropriate polarisation on $\widetilde{{\mathbb{P}}^n}$ and construct rank $2$ examples of locally free and non locally free (but torsion free) type. In general, the defined instantons also turn out to be cohomology of monads, although non linear ones. Moreover, in the five dimensional case, we show that there are continuous families of them that fill, at least, a smooth component in the moduli of semi-stable sheaves.

22 pages