Title：Searching for Afterglow: Light Dark Matter boosted by Supernova Neutrinos
Time：2022/09/12 (Mon.) 12:30
Place：R517, New Physics Building, NTU

Abstract:
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 $m_\chi\lesssim\mathcal{O}({\rm MeV})$ 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 BDM 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 $\sqrt{\sigma_{\chi e} \sigma_{\chi\nu}}$ are derived from SN1987a in Large Magellanic Cloud with data from the Kamiokande and Super-Kamiokande experiments. Potential sensitivities for the next Galactic SN with Hyper-Kamiokande are projected. Thi
 s analysis improves the existing bounds on $\sqrt{\sigma_{\chi e} \sigma_{\chi\nu}}$ by 1–3 orders of magnitude for $m_\chi\lesssim\mathcal{O}(100\,{\rm keV})$ for cases where $\sigma_{\chi e}$ and $\sigma_{\chi\nu}$ are of similar strength. Prospects of exploiting ToF information in other astrophysical systems to probe exotic physics with other DM candidates are discussed.