We give a complete classification of conformally covariant differential
operators between the spaces of differential i-forms on the sphere Sn and
j-forms on the totally geodesic hypersphere Sn−1 by analyzing the
restriction of principal series representations of the Lie group O(n+1,1).
Further, we provide explicit formul\ae{} for these matrix-valued operators in
the flat coordinates and find factorization identities for them.Comment: This note was published in C. R. Acad. Sci. Paris, Ser. I, (2016),
http://dx.doi.org/10.1016/j.crma.2016.04.01