I want to understand what concrete analytical objects are found in chiral homology of higher degree of a vertex algera (-module) $M$. More precisely: I can obtain conformal blocks on a surface $\Sigma$ for the Virasoro algebra as invariants of $M$ under the action of vector fields - for the torus one can then indeed work out a modular function depending on the structure of the torus and possibly the location of singularities. One can also compute elements in it by gluing the vertex operator on a 3-punctured sphere to a torus (a.k.a graded character of $M$)
But what about higher homologies: In the Lie algebra standard complex the chains are functions depending on an $n$-tuple of (here) vector fields up to...how does this relate for the torus to modular functions or something similar?
Same question for affine Lie algebra at negative level - I have found the great work of Gaitsgory, but I would like to know if there is any concrete analytic realization of the elements by...?
[But maybe it is simply the wrong question !?]
Also, I would already be very happy for reference like to as for references you might have on the chiral cohomology of the Virasoro algebra on surfaces (I know the computation for $M$ trivial, but for say $M$ a irrep of a minimal model?).
Thanks alot in advance, Simon Lentner