The paper explores whether a single unusual high-energy event seen by the LUX‑ZEPLIN (LZ) dark matter detector can be explained by a rare absorption of a fermionic dark matter particle by a xenon nucleus. LZ reported one candidate nuclear recoil, labeled LZ230616, reconstructed at about 248 ± 32.5 kilo‑electronvolts (keV) of nuclear recoil energy during an exposure of 2.80 ton·years. The LZ collaboration did not claim a statistically significant excess, but the event’s energy and shape motivate alternative explanations beyond standard elastic scattering.

The authors propose a neutral‑current absorption process in which a sub‑GeV fermionic dark matter particle is captured by a nucleus and its rest mass is converted into kinetic energy of the nucleus. For a dark matter mass of roughly 247 mega‑electronvolts (MeV), that process would produce a monoenergetic nuclear recoil right where LZ saw the event. At the same time, the same interaction strength would imply additional “incoherent” scattering at higher momentum transfer that knocks out individual protons or neutrons and produces a wide recoil spectrum extending from around a few hundred keV up to tens of MeV.

Using an effective field theory description, the authors find a single coupling can reproduce one event in the 248 keV window while not producing many events at lower energies. The single‑nucleon absorption cross section needed is about 1.07×10^−46 cm^2, which corresponds to an effective interaction scale of order 11.5 tera‑electronvolts (TeV) in their benchmark. They discuss two possible ultraviolet completions (ways to embed the interaction into a more complete particle physics model): a leptophobic vector mediator and a heavy scalar that couples through gluons. They also explain how the incoherent knockouts could be missed by LZ selection criteria, allowing the low‑energy spectrum to remain clean.