Inserted: 25 oct 2017
Last Updated: 6 feb 2018
We prove that half spaces are the only stable nonlocal $s$-minimal cones in $\mathbb R^3$, for $s\in (0,1)$ sufficiently close to 1. This is the first classification result of stable $s$-minimal cones in dimension higher than two. Its proof can not rely on a compactness argument perturbing from $s= 1$. In fact, our proof gives a quantifiable value for the required closeness of $s$ to 1. We use the geometric formula for the second variation of the fractional $s$-perimeter, which involves a squared nonlocal second fundamental form, as well as the recent BV estimates for stable nonlocal minimal sets.