A conjecture for q-decomposition matrices of cyclotomic v-Schur algebras

This is the final version (published version). No new result since Version 2, but major changes of the organization of the paper and the results. Some proofs and sections rewritten. References added and corrected.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