Rational homology cobordisms of plumbed manifolds and arborescent link concordance

We investigate rational homology cobordisms of 3-manifolds with non-zero first Betti number.
This is motivated by the natural generalization of the slice-ribbon conjecture to multicomponent links.

We introduce a systematic way of constructing rational homology cobordisms between plumbed 3-manifolds and concordances between arborescent links.

We then describe a sliceness obstruction based on Donaldson's diagonalization theorem that leads to a proof of the slice-ribbon conjecture for 2-component Montesinos' links up to mutation.