Loop Corrections To The Universal Hypermultiplet,” Phys

The universal hypermultiplet arises as a subsector of every Calabi-Yau compactifica-tion of M-theory or Type II string theory. Classically its moduli space is the quaternionic space SU (2, 1)/U (2). We show that this moduli space receives a one-loop correction proportional to the Euler character of the Calabi-Yau, which can locally be absorbed by a certain constant shift of the fields. The correction vanishes in the limit that the Planck mass is taken to infinity, and hence is essentially gravitational in nature.