ABSTRACT:
Bow varieties were introduced by Cherkis as analog of ADHM
type description of instanton moduli spaces on the Taub-NUT space (
$\mathbb C^2$ with a hyper-Kaehler metric, not an Euclidean one.) We
study these varieties from more algebro-geometric point of view, and
introduce their `multiplicative’ analog. Applications are their
identifications with Coulomb branches of 3d and 4d gauge theories
respectively.

The first part is joint work with Y.Takayama, while the second is with
D.Yamakawa