Rankin–Cohen type differential operators on Hermitian modular forms

We construct Rankin–Cohen type differential operators on Hermitian modular forms of signature (n, n). The bilinear differential operators given here specialize to the original Rankin–Cohen operators in the case \(n=1\) $n=1$ , and more generally satisfy some analogous properties, including uniqueness. Our approach builds on previous work by Eholzer–Ibukiyama in the case of Siegel modular forms, together with results of Kashiwara–Vergne on the representation theory of unitary groups.