Weighted cscK metric (II): the continuity method
Eleonora Di Nezza, Simon Jubert, Abdellah Lahdili
TL;DR
This work develops a comprehensive framework for metrics with weighted constant scalar curvature on compact Kähler manifolds endowed with a torus action. By introducing the $v$-weighted scalar curvature and the $(v,w)$-cscK equation, the authors prove that coercivity of the weighted Mabuchi energy $oldsymbol{M}_{v,w}$ implies the existence of a $(v,w)$-cscK metric, establishing a precise equivalence and unifying several geometric notions (classical cscK, Calabi extremal, weighted solitons, and extremal metrics on semisimple fibrations). The methodology hinges on a weighted Chen continuity path, with detailed openness, closeness, and regularity results, including robust $C^0$, $W^{1,2p}$, and entropy-based estimates. The paper also develops a toric Yau–Tian–Donaldson correspondence in the weighted setting and extends these results to semisimple principal fibrations, providing practical stability criteria and sufficient conditions in the toric case. Collectively, the findings offer powerful tools for analyzing weighted cscK metrics and their geometric consequences in toric and fibred contexts, with potential impact on stability notions and moduli.
Abstract
In this paper we investigate the existence of metrics with weighted constant scalar curvature (wcscK for short) on a compact Kähler manifold $X$: this notion include constant scalar curvature Kähler metrics, weighted solitons, Calabi's extremal Kähler metrics and extremal metric on semisimple principal fibrations. We prove that the coercivity of the weighted Mabuchi functional implies the existence of a wcscK metric, thereby achieving the equivalence. \\ We then give several applications in Kähler and toric geometry, such as a weighted version of the toric Yau-Tian-Donaldson correspondence, and the characterization of the existence of wcscK metric on total space of semisimple principal fibration $Y$ in term of existence of wcscK metric on its fiber $X$.
