Nonhomogeneous div-curl type estimates for system of complex vector fields on local Hardy spaces
Catarina Machado, Tiago Picon
TL;DR
This work extends the classical div-curl framework to a nonhomogeneous setting on local Hardy spaces for elliptic systems of complex vector fields with constant coefficients. It proves a global bound $\|V\cdot W\|_{h^1} \le C(\|V\|_{L^p}\|W\|_{L^{p'}} + \|{\rm div}_{\mathcal{L}^*} V\|_{L^p}\|W\|_{L^{p'}} + \|V\|_{L^p}\|{\rm curl}_{\mathcal{L}} W\|_{L^{p'}})$, and derives a local $bmo$-decomposition via the same div-curl structure. The authors reduce the proof to curl-zero and div-zero canonical cases using a Hodge-type decomposition and employ a priori estimates and maximal-function techniques to control the local Hardy norm. They then connect these estimates to a dual characterization of $bmo$ and provide a corollary giving a DC-based decomposition of $h^1$, along with a corollary that yields a precise div-curl representation for the $bmo$-duality. Overall, the results unify global nonhomogeneous div-curl phenomena with local Hardy space and $bmo$ duality for systems of constant-coefficient vector fields.
Abstract
In this work, we present a nonhomogeneous version of the classical div-curl type estimates in the setup of elliptic system of complex vector fields with constant coefficients on local Hardy space $h^1$. As an application, we obtain a decomposition of the local $bmo$ space via a family of vector fields depending on div-curl terms.
