The LUX-ZEPLIN (LZ) Collaboration recently reported the detection of a single nuclear recoil candidate event with a very high recoil energy. The absence of corresponding low-energy events suggests models where dark matter scattering with nuclei has a non-trivial momentum dependence or proceeds inelastically, suppressing the rate of low-energy recoils. This finding has reignited interest in inelastic dark matter models, where the dark matter particle must absorb energy to scatter, favoring higher-energy interactions.

A new study has investigated constraints on inelastic dark matter, including scenarios favored by the LZ event, based on the absence of an excess of high-energy neutrinos from the Sun in IceCube observations. The Sun, by accumulating dark matter in its interior, could generate high-energy neutrinos if dark matter annihilates or decays. The non-detection of an excess of these neutrinos imposes stringent limits on dark matter models.

The researchers confirm previous results by Pospelov and Ramani, demonstrating that the lack of an excess of high-energy neutrinos from the Sun strongly constrains the parameter space in this class of inelastic dark matter models. This implies that, while the LZ event is intriguing, the inelastic dark matter scattering mechanism must be compatible with the absence of secondary signals in other detectors, such as high-energy solar neutrinos.