  The Jantzen sum formula for cyclotomic v-Schur algebras yields an identity
for some q-analogues of the decomposition matrices of these algebras. We prove
a similar identity for matrices of canonical bases of higher-level Fock spaces.
We conjecture then that those matrices are actually identical for a suitable
choice of parameters. In particular, we conjecture that decomposition matrices
of cyclotomic v-Schur algebras are obtained by specializing at q=1 some
transition matrices between the standard basis and the canonical basis of a
Fock space.
