Interpreting the LZ 248 keV Event using Dark QCD

The LUX-ZEPLIN (LZ) Collaboration has reported a nuclear-recoil candidate with reconstructed energy $248\pm {23}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}}\pm {23}_{\mathrm{s}\mathrm{y}\mathrm{s}}\mathrm{k}\mathrm{e}\mathrm{V}$. We investigate an interpretation in terms of composite inelastic dark matter, in which a dimension-ten operator splits the lightest baryon of a confining $SU(3{)}_{\mathrm{D}}$ theory into two Majorana states. Endothermic scattering is mediated by a leptophobic vector coupled to baryon number. For a dark-baryon mass of $1\mathrm{T}\mathrm{e}\mathrm{V}$ and a splitting of $300\mathrm{k}\mathrm{e}\mathrm{V}$, a reference nucleon cross section of $6.5\times {10}^{-43}\mathrm{c}{\mathrm{m}}^2$ lies within LZ’s published two-sided 90% confidence interval. This benchmark fixes $M_V\mathrm{/}{g}_B\simeq 9.9\mathrm{T}\mathrm{e}\mathrm{V}$, where $M_V$ and $g_B$ are the mediator mass and baryon-number gauge coupling, and is compatible with solar neutrino and dijet constraints.