On sporadic symmetry breaking operators for principal series representations of the de Sitter and Lorentz groups

Abstract: In this paper, we construct and classify all differential symmetry breaking operators $\mathbb{D}{\lambda, \nu}^{N,m}: C^\infty(S^3, \mathcal{V}\lambda^{2N+1})\rightarrow C^\infty(S^2, \mathcal{L}_{m, \nu})$ between principal series representations with respect to the restriction $SO_0(4,1) \downarrow SO_0(3,1)$ when the parameters satisfy the condition $|m| > N$. In this case we also prove a localness theorem, namely, all symmetry breaking operators between the principal series representations above are necessarily differential operators. In addition, we show that all these symmetry breaking operators are sporadic in the sense of T. Kobayashi, that is, they cannot be obtained by residue formulas of distributional kernels.