The Lamm-Rivière system II: energy identity
Chang-Yu Guo, Wen-Juan Qi, Zhao-Min Sun, Changyou Wang
TL;DR
This work establishes angular energy quantization for the four-dimensional inhomogeneous Lamm-Rivière system, demonstrating that energy concentration occurs solely via finitely many bubbles and that the total energy splits between a limiting map and bubble energies. The authors develop a robust framework combining $\varepsilon$-regularity, energy gap, removable singularity, and weak compactness, with sharp neck estimates in Lorentz spaces to control tangential derivatives. They first prove the $L^p$-based angular-energy identity and then extend the result to the borderline case $f\in L\log L$, using $L\log L$ extensions and Calderón–Zygmund theory. The results generalize prior energy-identity results for biharmonic and Lamm-Rivière-type systems to the inhomogeneous, critical 4D setting and provide a precise bubble-tree decomposition underpinning the energy balance. The techniques leverage Lorentz-space tools and a detailed neck-analysis to offer sharp control of concentration phenomena in high-order elliptic systems with geometric structure.
Abstract
In this paper, we establish an angular energy quantization for the following fourth order inhomogeneous Lamm-Rivière system $$ Δ^2u=Δ(V\cdot\nabla u)+\text{div}(w\nabla u)+W\cdot\nabla u+f $$ in dimension four, with an inhomogeneous term $f\in L\log L$.
