Signatures of afterglows from light dark matter boosted by supernova neutrinos in current and future large underground detectors

Supernova neutrino boosted dark matter (SNν BDM) and its afterglow effect have been shown to be a promising signature for beyond Standard Model (bSM) physics. The time-evolution feature of SNν BDM allows for direct inference of DM mass m_χ, and results in significant background suppression with improving sensitivity. This paper extends the earlier study and provides a general framework for computing the SNν BDM fluxes for a supernova that occurs at any location in our galaxy. A bSM U(1)_L_μ-L_τ model with its gauge boson coupling to both DM and the second and third generation of leptons is considered, which allows for both DM-ν and DM-e interactions. Detailed analysis of the temporal profile, angular distribution, and energy spectrum of the SNν BDM are performed. Unique signatures in SNν BDM allowing extraction of m_χ and detail features that contain information of the underlying interaction type are discussed. Expected sensitivities on the above new physics model from Super-Kamiokande, Hyper-Kamiokande, and DUNE detections of BDM events induced by the next galactic SN are derived and compared with the existing bounds.