Minimality of the ball for a model of charged liquid droplets

We prove that charged liquid droplets minimizing Debye-Huckel-type free energy are spherical in the small charge regime. The variational model was proposed by Muratov and Novaga in 2016 to avoid the ill-posedness of the classical one. Combining a recent (partial) regularity result with the selection principle of Cicalese and Leonardi, we prove that the ball is the unique minimizer in the small charge regime.