A nonlinear Calderón-Zygmund $ L^2$-theory for the Dirichlet problem involving $ -|Du|^γΔ^N_p u=f$
Qianyun Miao, Fa Peng, Yuan Zhou
Abstract
We establish a nonlinear Calderón-Zygmund $L^2$-theory to the Dirichlet problem $$-|Du|^γΔ^N_p u=f\in L^2(Ω)\quad {\rm in}\quad Ω; \quad u=0 \ \mbox{on $\partialΩ$} $$ for $n\ge2$, $ p>1$ and a large range of $γ>-1$, in particular, for all $p>1$ and all $ γ>-1$ when $n=2$. Here $Ω\subset \mathbb{R}^n$ is a bounded convex domain, or a bounded Lipschitz domain whose boundary has small weak second fundamental form in the sense of Cianchi-Maz'ya (2018). The proof relies on an extension of an Miranda-Talenti \& Cianchi-Maz'ya type inequality, that is, for any $v\in C^\infty_0(Ω)$ in any bounded smooth domain $Ω$, $\|D[(|Dv|^2+ε)^{\fracγ2}Dv]\|_{L^2(Ω)}$ is bounded via $\|(|Dv|^2+ε)^{\fracγ2} Δ^N_{p,ε}v \|_{L^2(Ω)}$, where $Δ^N_{p,ε}v$ is the $ε$-regularization of normalized $p$-Laplacian. Our results extend the well-known Calderón-Zygmund $L^2$-estimate for the Poisson equation, a nonlinear global second order Sobolev estimate for inhomogeneous $p$-Laplace equation by Cianchi-Maz'ya (2018), and a local $W^{2,2}$-estimate for inhomogeneous normalized $p$-Laplace equation by Attouchi-Ruosteenoja (2018).
