Aspinwall, PS; Morrison, DR, *Topological field theory and rational curves*,
Communications in Mathematical Physics, vol. 151 no. 2
(1993),
pp. 245-262 [doi] .
**Abstract:**

*We analyze the quantum field theory corresponding to a string propagating on a Calabi-Yau threefold. This theory naturally leads to the consideration of Witten's topological non-linear σ-model and the structure of rational curves on the Calabi-Yau manifold. We study in detail the case of the world-sheet of the string being mapped to a multiple cover of an isolated rational curve and we show that a natural compactification of the moduli space of such a multiple cover leads to a formula in agreement with a conjecture by Candelas, de la Ossa, Green and Parkes. © 1993 Springer-Verlag.*