Production and attenuation of cosmic-ray boosted dark matter

Abstract

Light sub-GeV halo dark matter (DM) particles up-scattered by high-energy cosmic-rays (CRs) (referred to as CRDM) can be energetic and become detectable by conventional DM direct detection experiments. We perform a refined analysis on the exclusion bounds of the spin-independent DMnucleon scattering cross section σ χp in this approach. For the exclusion lower bounds, we determine the parameter of the effective distance D eff for CRDM production using spatial-dependent CR fluxes and including the contributions from the major heavy CR nuclear species. We obtain D eff 9 kpc for CRDM particles with kinetic energy above ∼ 1 GeV, which pushes the corresponding exclusion lower bounds down to σ χp ∼ 4 × 10 −32 cm 2 for DM particle mass at MeV scale and below. For the exclusion upper bounds from Earth attenuation, previous estimations neglecting the nuclear form factor leaded to typical exclusion upper bounds of σ χp ∼ O(10 −28 ) cm 2 from the XENON1T data. Using both the analytic and numerical approaches, we show that for CRDM particles, the presence of the nuclear form factor strongly suppresses the effect of Earth attenuation. Consequently, the cross section that can be excluded by the XENON1T data can be a few orders of magnitude higher, which closes the gap in the cross sections excluded by the XENON1T experiment and that by the astrophysical measurements such that for the cosmic microwave background (CMB), galactic gas cloud cooling, and structure formation, etc..

A Search for the Cosmic Ray Boosted Sub-GeV Dark Matter at the PandaX-II Experiment

“…On the other hand, as pointed out by Ref. [43], the form factor suppression significantly reduces the scattering probability and angular deflection for high energy CRDM. Such stepping process is repeated until the DM reaches the CJPL site, exits the mountain, or stops completely.…”

“…It has also been realized that certain processes could boost the kinetic energy of the Galactic DM, leaving detectable energy in the detector [29][30][31][32][33][34][35][36][37][38]. In particular, the detectability of the cosmic ray boosted dark matter (CRDM) has been widely recognized since the upscattering of the DM would be inevitable were there finite DM-nucleus interactions [4,[38][39][40][41][42][43][44][45][46][47].…”

“…An independent Monte Carlo (MC) simulation is developed to incorporate details of the scatterings using similar approaches as in Refs. [41,43,48,59]. The CRDM particles are randomly generated on the Jinping mountain surface (50 km×50 km) according to their sky distribution at a given sidereal time, with energy above 1 GeV truncated to avoid inelastic contributions [39,48].…”

“…(2) with the form factor included as suggested by Ref. [43], whereas in the PROSPECT's treatment, the form factor suppression in the mean-free-path is conservatively omitted [68]. For illustration, the exclusion contour adopting the same treatment as PROSPECT is shown as the dashed blue curve in Fig.…”

Direct Detection of Spin-Dependent Sub-GeV Dark Matter via Migdal Effect

“…Besides, like the SI scattering (see e.g. [70] and the references therein), when the DM-nucleus interaction is strong, we should mention that the earth stopping effect may attenuate the flux and produce the bound on the SD scattering cross section as well. Such a…”