The RR charges of A-type Gepner models
  It is shown that the RR charges of Gepner models are not all accounted for by the usual tensor product and permutation branes. In order to characterise the missing D-branes we study the matrix factorisation approach to the description of D-branes for Gepner models. For each of the A-type models we identify a set of matrix factorisations whose charges generate the full lattice of quantised charges. The additional factorisations that are required correspond to generalised permutation branes. 
Claudio Caviezel, Stefan Fredenhagen and Matthias R. Gaberdiel