Searching for Afterglow: Light Dark Matter Boosted by Supernova Neutrinos

A novel analysis is performed, incorporating time-of-flight (TOF) information to study the interactions of dark matter (DM) with standard model particles. After supernova (SN) explosions, DM with mass m chi less than or similar to O(MeV) in the halo can be boosted by SN neutrinos (SN nu) to relativistic speed. The SN nu boosted DM (BDM) arrives on Earth with TOF which depends only on m chi and is independent of the cross section. These BDMs can interact with detector targets in low-background experiments and manifest as afterglow events after the arrival of SN nu. The characteristic TOF spectra of the BDM events can lead to large background suppression and unique determination of m chi. New cross section constraints on ffiffiffiffiffiffiffiffiffiffiffiffi SN1987a in the Large Magellanic Cloud with data from the Kamiokande and Super-Kamiokande experiments. Potential sensitivities for the next galactic SN with Hyper-Kamiokande are projected. This analysis extends the existing bounds on ffiffiffiffiffiffiffiffiffiffiffiffi ,V over a broad range of r chi = sigma chi nu/sigma chi e. In particular, the improvement is by 1-3 orders of magnitude for m chi < O(100 keV) for sigma chi e similar to sigma chi nu. Prospects of exploiting TOF information in other astrophysical systems to probe exotic physics with other DM candidates are discussed.