Holomorphic functional calculus of Hodge-Dirac operators in Lp

TL;DR

This paper investigates the conditions under which Hodge-Dirac operators have a bounded $H^{ abla}$ functional calculus in $L^p$ spaces, extending previous results to variable coefficients and establishing stability under perturbations.

Contribution

It provides new criteria for the boundedness of the $H^{ abla}$ calculus for Hodge-Dirac operators with variable coefficients in $L^p$, generalizing prior $L^2$ results.

Findings

Characterization of bounded $H^{ abla}$ calculus via randomized resolvent boundedness.

Extension of $L^p$ theory for Hodge-Dirac operators with variable coefficients.

Stability results under small perturbations of the functional calculus.

Abstract

We study the boundedness of the $H^{\infty}$ functional calculus for differential operators acting in (L^{p}(\mathbb{R}^{n};\mathbb{C}^{N})). For constant coefficients, we give simple conditions on the symbols implying such boundedness. For non-constant coefficients, we extend our recent results for the (L^p) theory of the Kato square root problem to the more general framework of Hodge-Dirac operators with variable coefficients (\Pi_B) as treated in (L^2(\mathbb{R}^{n};\mathbb{C}^{N})) by Axelsson, Keith, and McIntosh. We obtain a characterization of the property that (\Pi_B) has a bounded (H^{\infty}) functional calculus, in terms of randomized boundedness conditions of its resolvent. This allows us to deduce stability under small perturbations of this functional calculus.