Unitarity of type E genuine small representations

Determine whether the genuine small representations arising from the lift of the trivial representation for simply laced real groups of type $E$ are unitary.

Background

Earlier work computed the lift of the trivial representation for simply laced, split real semisimple groups. The resulting genuine small representations have infinitesimal character ρ/2\rho/2 and are associated with a specific nilpotent orbit characterized by maximal τ\tau-invariant.

The introduction states that the corresponding representations in types AA and DD are known to be unitary, whereas the type EE case has not been settled. This is a specific unresolved instance of the broader question of whether character lifting preserves unitarity.

References

For the genuine small representations arising from the lift of the trivial representation in , those of types $A$ and $D$ are known to be unitary, while the corresponding question in type $E$ remains open.

Unitary Shimura Correspondence for Complex Classical Groups  (2608.26795 - Tsai et al., 27 Aug 2026) in Section 1, Introduction