It is in general very subtle to integrate over the odd moduli of superRiemann surfaces in perturbative superstring computations. We study how thesesubtleties go away in favorable cases, including the embedding of N=0 string toN=1 string by Berkovits and Vafa, and the relation of the graviphoton amplitudeand the topological string amplitude by Antoniadis, Gava, Narain and Taylor andBershadsky, Cecotti, Ooguri and Vafa. The Poincar\'e dual of the moduli spaceof Riemann surfaces in the moduli space of super Riemann surfaces plays animportant role.
展开▼
