Dark Parton Shower Effects for Cosmic Ray Boosted Dark Matter

Abstract We investigate the dark parton shower effects in the direct detection of cosmic-ray boosted dark matter(CRDM), focusing on a dark photon-mediated model with fermionic dark matter-electron interactions. Utilizing a Monte Carlo framework to incorporate the Sudakov form factors and kinematic dipole recoil schemes, we simulate the CRDM energy spectrum evolution under the dark sector splitting. Our results reveal an energy-dependent reshaping of the CRDM flux induced by dark parton showering, characterized in particular by a depletion of the high-energy flux. For a 1 keV dark matter (DM) mass and a coupling of g D =3, the CRDM flux can be enhanced by a factor up to 1.12 in the Ο(10 -2 ∼1) MeV energy range for 2m χ ≲m A ' ≲10 -2 MeV, while it is suppressed by more than 50% at energy around 100 MeV for m A ' ≲10 -3 MeV. We then translate these effects into the experimental sensitivities for PandaX-4T, Super-Kamiokande, and JUNO. At m A ' =10 -3 MeV and g D =3, the bounds on the kinetic mixing parameter ε 2 are relaxed by factors of 1.02, 1.6 and 1.4, respectively. When incorporating the effects of DM parton distribution functions (PDFs) at neutrino detectors alongside dark parton shower effects, the bounds are further relaxed. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.