Searching for sub-MeV boosted dark matter from xenon electron direct detection *

Abstract

Direct detection experiments tend to lose sensitivity in searches for sub-MeV light dark matter candidates due to the threshold of recoil energy. However, such light dark matter particles could be accelerated by energetic cosmic rays, such that they could be detected with existing detectors. We derive constraints on the scattering of a boosted light dark matter particle and electron from the XENON100/1T experiment. We illustrate that the energy dependence of the cross section plays a crucial role in improving both the detection sensitivity and also the complementarity of direct detection and other experiments.

Implications of the XENON1T excess on the dark matter interpretation

“…We have followed the procedure described in refs. [34,57] to compute the ionization form factor for the interaction between BDM and the electrons in a xenon atom. We consider three outermost orbitals (5p, 5s, and 4d), with respective binding energies ∼12, 26 and 76 eV, which are known to be the JHEP05(2021)055 Figure 6.…”

“…[2] used the atomic excitation factor with relativistic corrections and ref. [34] considered the dark matter and ionization form factors, restricting to the N -shell and O-shell electrons. We here take a shortcut scheme, reserving a dedicated analysis for future work [35].…”

“…We here take a shortcut scheme, reserving a dedicated analysis for future work [35]. As a conservative approach, we consider electrons from three outermost orbitals (5p,5s and 4d), which are known to be the dominant contribution [34,36,37], i.e., the number of target electrons in a single xenon atom N eff e is taken to be 18 throughout our analysis. 3 Note that the largest ionization energy among the electrons belonging to the three orbitals is ∼ 76 eV [32] which would induce less than 5% uncertainty in estimating 2 − 3 keV energy deposition.…”

Global fits of axion-like particles to XENON1T and astrophysical data

“…A large number of physics scenarios have been put forward to explain the excess in the electronic recoil spectrum observed by XENON1T. One set of options is based around the existence of dark matter (DM) particles that either scatter inelastically in the detector [4,5,12,21,37,[46][47][48] or are boosted to semi-relativistic velocities via some other process before scattering elastically off electrons [10,15,17,[49][50][51][52]. A 2 keV -3 keV dark photon with a small (10 −15 ) kinetic mixing with ordinary photons [2,16,[53][54][55] or a massive dark photon produced from solar emission [6,11,54] (with the caveat of ref.…”

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

“…Then the ionized electrons drift into the Gaseous Xenon layer at the top of the detector in presence of an external electric field, and then collide with the xenon atoms, which produces a proportional scintillation light, namely the S2 signal. In theory, such ionization signals can come from the DM-electron scattering [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] or the DM-nucleus scattering through the Migdal effect that originates from non-instantaneous movement of electron cloud during a nuclear recoil event [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. The Migdal scattering is usually sub-dominant to the conventional nuclear scattering, but can take place in a very low energy nuclear recoil, which has been used to improve the sensitivity of the DM-nucleus interactions in the low DM mass region [40][41][42].…”