On dimensions of RoCK blocks of cyclotomic quiver Hecke superalgebras

We explicitly compute the dimensions of certain idempotent truncations of RoCK blocks of cyclotomic quiver Hecke superalgebras. Equivalently, this amounts to a computation of the value of the Shapovalov form on certain explicit vectors in the basic representations of twisted affine Kac-Moody Lie algebras of type $A$.