Moduli dependent non-holomorphic contributions of massive states to gravitational couplings and C2-terms in ZN-orbifold compactifications Original Research Article

It is pointed out that massive states in D = 4, N = 1 supergravity-matter theories can, in general, at the 1-loop level contribute non-holomorphic terms to quadratic gravitational couplings. It is then shown in the context of (2,2)-symmetric ZN-orbifold theories that, for constant moduli backgrounds, the inclusion of such contributions can result in the cancellation of naked C2-terms. R2-terms can also arise but, being ghost free, need not cancel.