Ricci-DeTurck Flow from Initial Metric with Morrey-type Integrability Condition
Man-Chun Lee, Stephen Shang Yi Liu
TL;DR
The paper develops a rough existence theory for the Ricci-DeTurck flow from metrics $g_0$ with Morrey-type integrability, establishing short-time existence with quantitative estimates and convergence to $g_0$. It uses parabolic bootstrapping and heat-kernel techniques to obtain interior gradient and higher-derivative bounds, even in the presence of a controlled singular set $\Sigma$. A key contribution is showing that distributional lower bounds on scalar curvature are preserved under the flow when $g_0$ satisfies Morrey-type regularity, leading to a removable singularity-type conclusion in the compact case. The work generalizes prior results (notably Jiang-Sheng-Zhang) and provides tools for smoothing rough metrics while maintaining scalar curvature rigidity, with implications for geometric analysis under low regularity.
Abstract
In this work, we study the short-time existence theory of Ricci-DeTurck flow starting from rough metrics which satisfy a Morrey-type integrability condition. Using the rough existence theory, we show the preservation and improvement of distributional scalar curvature lower bounds provided the singular set for such metrics is not too large. As an application, we use the Ricci flow smoothing to study the removable singularity for scalar curvature rigidity in the compact case under Morrey regularity conditions. Our result supplements those of Jiang-Sheng-Zhang.
