  Light halo dark matter (DM) particles up-scattered by high-energy cosmic rays
(referred to as CRDM) can be energetic and become detectable at conventional DM
and neutrino experiments. We show that the CRDM flux has a novel and detectable
morphological feature. Unlike most of the recently proposed boosted DM (BDM)
models which predict azimuthally symmetric DM fluxes around the Galactic
Center, the CRDM flux breaks the azimuthal symmetry significantly. Using
cosmic-ray electron distribution in the whole Galaxy and optimized search
region in the sky according to the morphology of the CRDM flux, we derive so
far the most stringent constraints on the DM-electron scattering cross section
from the Super-Kamiokande (SK) IV data, which improves the previous constraints
from the SK-IV full-sky data by more than an order of magnitude. Based on the
improved constraints, we predict that the azimuthal symmetry-breaking effect
can be observed in the future Hyper-Kamiokande experiment at $\sim 3\sigma$
level.

High Energy Physics - Phenomenology