Locate the tree–loop cancellation band and IceCube-allowed region

Locate the cancellation band produced by coherent interference between the tree-level light-Higgs-exchange and electroweak-loop spin-independent amplitudes in the small-splitting MSSM Higgsino parameter surface, determine its width, and identify the corresponding IceCube-allowed region by performing a point-by-point loop-complete signed-amplitude calculation together with the solar capture, orbit, and thermalization analysis, including residual spin-dependent interactions.

Background

The paper argues that a TeV-scale Higgsino can undergo inelastic capture in the Sun through its off-diagonal Z interaction. Subsequent migration of the captured Higgsinos toward the solar core depends on residual elastic scattering. The relevant spin-independent elastic amplitude receives a tree-level contribution from light-Higgs exchange, which depends on finite gaugino–Higgsino mixing, and a nonzero electroweak-loop contribution that persists in the pure-Higgsino limit.

The authors show that the magnitudes of the tree-level and loop contributions can be comparable and that their relative signs can permit destructive interference. Such interference could suppress the elastic cross section, delay solar thermalization, reduce the annihilation rate in the solar core, and thereby weaken the IceCube neutrino constraint. However, the displayed analysis does not calculate the coherent amplitudes consistently across parameter space or determine the resulting solar response, so the location and width of the cancellation band and the associated IceCube-compatible region remain unresolved.

References

This argument does not locate a cancellation band. Doing so requires the tree and loop Wilson coefficients to be evaluated point by point in one operator basis, Majorana-phase convention, renormalization scheme, and set of hadronic inputs, followed by the solar capture-and-orbit calculation. The residual spin-dependent interaction must also be retained when translating a suppressed spin-independent rate into a thermalization time. We therefore use Fig.~\ref{fig:elastic-scales-supp} only to motivate the interference mechanism and do not assign a location or width to an IceCube-allowed region.

— TeV Higgsino Dark Matter from LZ Nuclear Recoil to Fermi-LAT Gamma Rays  (2609.01590 - Wu et al., 1 Sep 2026) in Supplemental Material, Section "Solar thermalization and the elastic amplitude" (Section 4)