In

http://arxiv.org/PS_cache/hep-th/pdf/9302/9302103v1.pdf

physicists calculate (predict) genus one GW invariants of quintic (Table 1) and some other cases (Table 2).

Can any body explain to me (mathematically) how do they do that? What is the B-model object (integral) which they consider and extract these numbers from (conjecturally via some mirror relation) ?

Please at least try to explain mathematically.