We study the scalar curvature of Kähler metrics that have cone singularities along a divisor, with a particular focus on certain specific classes of such metrics that enjoy some curvature estimates. Our main result is that, on the projective completion of a pluricanonical bundle over a product of Kähler-Einstein Fano manifolds with the second Betti number 1, momentum-constructed constant scalar curvature Kähler metrics with cone singularities along the ∞-section exist if and only if the log Futaki invariant vanishes on the fibrewise C * -action, giving a supporting evidence to the log version of the Yau-Tian-Donaldson conjecture for general polarisations. We also show that, for these classes of conically singular metrics, the scalar curvature can be defined on the whole manifold as a current, so that we can compute the log Futaki invariant with respect to them. Finally, we prove some partial invariance results for them. n i=2 √ −1dz i ∧ dz i around D, with coordinates (z 1 , . . . , z n ) as above. The above definition is more restrictive than this usual definition, but will include all the cases that we shall treat in this paper (cf. Definition 1.10).Remark 1.3. We can regard a conically singular metric ω sing as a (1, 1)-current on X, and hence can make sense of its cohomology class [ω sing ] ∈ H 2 (X, R).
2Kähler-Einstein metrics with cone singularities along a divisor, studied initially in [27,37,47,50], attracted renewed interest since the foundational work of Donaldson [21] on the linear theory of Kähler-Einstein metrics with cone singularities along a divisor. Since then, there has already been a huge accumulation of research on such metrics.We now recall the log K-stability, which was introduced by Donaldson [21] and played a crucially important role in proving the Yau-Tian-Donaldson conjecture (Conjecture 2.6) for Fano manifolds; see Remark 2.16. We first recall (cf. Theorem 2.10) that the notion of K-stability can be regarded as an "algebro-geometric generalisation" of the vanishing of the Futaki invariant