A factorisation theorem for curve with vanishing self-intersection

Abstract

Let C be a curve in a compact Kahler surface Y. Assume that the self-intersection of C is vanishing, and the image of the fundamental group of C in Y is of infinite index in the fundamental group of Y. Does it follow that C is a fiber of a holomorphic map from Y to a curve ? We give, in some cases, a positive answer to the question. Our strategy is to solve a Poincare-Lelong equation on some infinite covering of Y.