The effect of boundary geometry in nonlocal critical problems with Hardy-Littlewood-Sobolev exponent
Hichem Chtioui, Tuhina Mukherjee, Lovelesh Sharma
TL;DR
This work analyzes a nonlocal Choquard equation with upper Hardy-Littlewood-Sobolev exponent under mixed Dirichlet-Neumann boundary conditions on a bounded domain. The authors establish how the geometry of the Neumann boundary portion $\Gamma_1$ influences the existence of ground state solutions by introducing a local flatness condition $(\mathbf{H_1})$ and deriving variational estimates. Using an Aubin-type minimization argument and carefully crafted test functions derived from HL ground-state profiles, they show that the minimization constant $S_{HL}(\Gamma_0)$ is attained under either $\beta<3$ (no extra $V$ assumptions) or $V\le0$ near the boundary (any $\beta$ up to $n-1$). This links boundary geometry, particularly mean curvature in the local model, to the solvability of critical nonlocal problems on bounded domains. The results extend prior flatness/mean-curvature conditions for Neumann problems to the nonlocal Choquard setting and provide explicit mechanisms to ensure ground states exist.
Abstract
In this paper we consider a mixed Dirichlet-Neumann boundary value problem. lem involving Choquard nonlinearity with upper critical exponent in the sense of Hardy- Littlewood Sobolev inequality. We investigate the effect of the geometry of the boundary part where the Neumann condition is prescribed on the existence problem of ground state solutions.
