“…In particular, it is unclear what vertex operator one would write in D 4 -Toda; indeed, in the little string formalism, the defect is the null weight, which suggests a trivial conformal block with no vertex operator insertion! To investigate this issue more carefully, it is useful to keep m s finite and work in the little string proper; there, a computation in the spirit of [7,50,51], shows that the partition function of T 2d is in fact not a q-conformal block of D 4 Toda, due to subtleties of certain non-cancelling fugacities. In other words, the claim that the partition function of T 2d is a q-conformal block of g-type Toda fails precisely when T 2d is an unpolarized defect, and only for those cases.…”