Smooth projective surfaces with pseudo-effective tangent bundles

Abstract

Let $S$ be a non-uniruled (i.e., non-birationally ruled) smooth projective surface. We show that the tangent bundle $T_S$ is pseudo-effective if and only if the canonical divisor $K_S$ is nef and the second Chern class vanishes, i.e., $c_2(S)=0$. Moreover, we study the blow-up of a non-rational ruled surface with pseudo-effective tangent bundle.