A theta operator on Picard modular forms modulo an inert prime
  We study the reduction of Picard modular surfaces modulo an inert prime, mod p and p-adic modular forms. We construct a theta operator on such modular forms and study its poles and its effect on Fourier-Jacobi expansions. 
Ehud de Shalit and Eyal Z. Goren
math.NT math.AG