NNLO soft function for electroweak boson production at large transverse momentum

The soft function relevant for the production of an electroweak boson (γ, W, Z or H) with large transverse momentum at a hadron collider is computed at next-to-next-to-leading order. This is the first two-loop computation of a soft function describing emissions from energetic partons in three directions. With the result, the threshold resummation for these processes can now be performed at next-to-next-to-next-to-leading logarithmic accuracy.