A congruous approach with realistic cross section towards limiting sub-GeV dark matter from LUX-ZEPLIN

Abstract: We present constraints on sub-GeV dark matter (DM) through the mechanism of being boosted by cosmic rays (CRs). We utilize the nuclear recoil data from the LUX-ZEPLIN (LZ) experiment for this purpose. Without the mechanism of boosted dark matter (BDM), sub-GeV DM particles are cold enough to produce detectable nuclear recoil in the LZ experiment above the detector threshold. We choose to work with the leading components of cosmic rays to take into account the boost due to them towards the cold DM. In the present discussion we worked on models consisting of a Dirac fermion $\chi$ with a new $U(1)'$ gauge symmetry and DM particles have non-zero coupling to the nucleons as per the model parameters. Specific examples of the energy dependence of the scattering cross section have been invoked through the secluded dark photon model and $U(1)_{B-L}$ model. Additionally, we present the upper bound on the interaction cross section due to the Earth shielding effect in the light of a systematic analysis of the energy loss by the BDM while traveling to the underground detector through the Earth's crust.