Measurement outcomes for the spherically symmetric 4D exotic wavefunction

Determine whether measurements of the spherically symmetric s-wave four-dimensional wavefunction—obtained by interpreting the two-dimensional transformed state as the s-wave component of four-dimensional fermions and attached to a volume defect between two spherical shells—yield spherically symmetric detection outcomes or angularly localized events; specify and analyze concrete measurement protocols to resolve this question and characterize how the answer depends on the measurement details.

Background

After constructing explicit two-dimensional wavefunctions for exotic excitations scattered by the Maldacena–Ludwig wall, the authors note that the same expressions can be used as the s-wave part of a four-dimensional fermionic scattering state. In this four-dimensional interpretation, the state is spherically symmetric and can be viewed as being attached to a volume defect between two spherical shells.

The authors explicitly raise the question of what a measurement would observe in such a state: whether detection outcomes remain spherically symmetric or become localized in angle. They acknowledge uncertainty and emphasize that a definitive answer requires specifying the measurement protocol, highlighting an unresolved problem at the interface of quantum measurement and the constructed scattering states.

References

The four-dimensional wavefunction suggested in A\ref{Q:4d} is spherically symmetric, and would be `attached' in the sense of A\ref{Q:defect} to a volume-defect filling the region between two spherical shells. What happens when we measure this wavefunction? Do we get a spherically-symmetric result, or a result localized in the angular direction? The authors are not sure, but the following discussion might be of some use.

What happens to wavepackets of fermions when scattered by the Maldacena-Ludwig wall?  (2603.25508 - Tachikawa et al., 26 Mar 2026) in Section 4 (Conclusions and Outlook), Q&A: final question