Three Balls Theorem for Eigenfunctions of Dirac Operator in Clifford Analysis

In this paper we establish the three balls theorem for functions $u$ satisfying $Du=\lambda u$ in Clifford analysis, where $D$ is the Dirac operator. As an application, we generalize Hadamard’s three circles theorem to monogenic function in ${\mathbb{R}}^{n+1}\mathrm{.}$