The LUX‑ZEPLIN (LZ) experiment recently reported a single high‑energy nuclear recoil event, detected in 2.84 tonne‑years of liquid xenon exposure. That lone event, named LZ230616, stood out because there were few low‑energy recoils nearby. This led researchers to consider dark matter models that naturally suppress low‑energy collisions, in particular inelastic scattering where a dark matter particle converts into a slightly heavier state during a collision.

The authors of this paper tested those inelastic dark matter ideas against observations of the Sun made by the IceCube neutrino telescope. Their basic logic is simple. If dark matter can hit nuclei in LZ, it can also scatter in the Sun. Scattering in the Sun can slow dark matter down enough that it becomes trapped by the Sun’s gravity. Trapped dark matter can then annihilate with itself and produce high‑energy neutrinos. IceCube looks for such neutrinos, so a lack of a neutrino excess limits how much dark matter can be captured and annihilated in the Sun.

Inelastic scattering works differently from ordinary elastic scattering. In the inelastic case the dark particle must have enough kinetic energy to jump to a heavier internal state. That requirement raises a minimum incoming speed for low recoil energies, which suppresses low‑energy signals in detectors like LZ while allowing rarer, higher‑energy recoils. A mass splitting of a few hundred kilo‑electronvolts can therefore make a very high recoil plausible at LZ without predicting many low‑energy events.

The Sun changes the picture because its gravity accelerates incoming dark matter particles. That extra speed lets dark matter scatter inelastically on heavy solar nuclei that would be kinematically inaccessible at Earth. Even elements that are rare in the Sun, such as very heavy nuclei, can play an outsize role in capturing and cooling dark matter. If captured dark matter annihilates into particles that produce high‑energy neutrinos, IceCube should see an excess. The authors compute capture and annihilation rates under standard solar and dark matter assumptions and compare them to IceCube limits.