The Alt-Phillips functional for negative powers

Abstract: We develop the free boundary regularity for nonnegative minimizers of the Alt-Phillips functional for negative power potentials $$\int_\Omega \left(\frac 1 2 |\nabla u|^2 + u^{\gamma} \chi_{{u>0}}\right) \, dx, \quad \quad \gamma \in (-2,0),$$ and establish a $\Gamma$-convergence result of the rescaled energies to the perimeter functional as $\gamma \to -2$.