Inelastic $B-L$ scalar dark matter and the LUX-ZEPLIN event

Abstract

We show that our previously proposed inelastic scalar dark matter (DM) model in gauged $U(1)_{B-L}$ symmetry naturally accounts for the $2.6σ$ high-energy recoil event recently reported by the LUX-ZEPLIN (LZ) collaboration. To satisfy the thermal relic abundance, TeV-scale scalar DM $S$ with $m_S \simeq m_{Z'}/2$ for resonant annihilation and the gauge coupling constant $g_{B-L} \sim 0.5$ are required, where $m_{Z^\prime}$ is the mass of $U(1)_{B-L}$ gauge boson $Z^{\prime}$. The resulting predicted DM-nucleon inelastic cross section of $σ_\mathrm{SI} \sim 10^{-45}$ cm${}^2$ is in excellent agreement with the LZ event. This scenario can be decisively tested for future collider searches for $Z^\prime$ boson resonance.