Heegaard Floer correction terms, with a twist

We use Heegaard Floer homology with twisted coefficients to define numerical invariants for arbitrary closed 3-manifolds equipped torsion spinc structures, generalising the correction terms (or d--invariants) defined by Ozsv\'ath and Szab\'o for integer homology 3-spheres and, more generally, for 3-manifolds with standard HF∞. Our twisted correction terms share many properties with their untwisted analogues. In particular, they provide restrictions on the topology of 4-manifolds bounding a given 3-manifold