M. Dajczer et R. Tojeiro, FLAT TOTALLY-REAL SUBMANIFOLDS OF CP(N) AND THE SYMMETRICAL GENERALIZED WAVE-EQUATION, Tohoku Mathematical Journal, 47(1), 1995, pp. 117-123
In this paper we show that the projection of the Hopf fibration establ
ishes a one-to-one correspondence between the set of symmetric flat su
bmanifolds in Euclidean sphere and the set of totally real flat subman
ifolds in complex projective space with the same codimension. We also
show that any complete totally real submanifold in complex projective
space with mean curvature of constant length and equal dimension and c
odimension is a flat torus.