Constraints on Dark Matter with a moderately large and velocity-dependent DM-nucleon cross-section

Abstract

We derive constraints on a possible velocity-dependent DM-nucleon scattering cross section, for Dark Matter in the 10 MeV -100 GeV mass range, using the XQC, DAMIC, and CRESST 2017 Surface Run experiments. We report the limits on cross sections of the form σ = σ 0 v n , for a range of velocity dependencies with n ∈ {−4, −2, −1, 0, 1, 2}. We point out the need to measure the efficiency with which nuclear recoil energy in the sub-keV range thermalizes, rather than being stored as Frenkel pairs in the semi-conductor lattice. The possibility of a significant inefficiency leaves open a considerable "hole" in the limits for mass in the ∼ 0.2 -2 GeV range, which XQC and CRESST can potentially fill when the thermalization efficiency is measured. We call attention to the asymmetry between a conventional lower limit cross section and the "upper-reach cross section" imposed by attenuation in an overburden -an upper boundary being extremely sharp but quite insensitive to the statistics of the experiment. Considering the recent interest to use dark matter-baryon interaction with velocity dependence n = −4 to explain the EDGES 21 cm anomaly, we also derive the limits on milli-charged DM that scatters off protons and electrons under a Coulomb-like interaction. We find that much but not all of the region of interest for the EDGES anomaly can be excluded.

Direct detection of strongly interacting sub-GeV dark matter via electron recoils

“…In addition to the bounds derived in this paper (see Fig. 4, top left), we also show constraints from nuclear recoil DM-searches by XENON1T [83], CRESST-II [84], the CRESST 2017 surface run [85] as obtained in [44], as well as the lower boundaries obtained by CRESST-III [86] and CDEX (Migdal effect) [87], together with constraints from the X-ray Quantum Calorimeter experiment (XQC) [45], cosmic-rays ("CRDM") [88], CMB [59], and Milky-Way satellites [89]. We do not show collider or beam-dump bounds, but see e.g.…”

“…This energy loss affects the rate of events produced at the direct detection experiments as the DM particles traveling through the medium get scattered off the nuclei before reaching the detector, and their speed distribution changes. This was investigated using the analytic approach of the stopping power for contact interactions [38][39][40][41]80], dipole interactions [75], and light mediators [45]. In contrast, we use MC techniques to simulate the nuclear scatterings and precisely calculate the change in the underground distribution of DM particles.…”

“…We show in Fig. 11 the constraint for XQC, where we have naively rescaled to f χ = 0.4% the most conservative XQC constraints for f χ = 1% taken from [45]. At even higher masses (m χ ≥ 1 GeV), we use data from a high-altitude nuclear recoil experiments labelled "RRS" to constrain the open parameter space between the upper boundary of the direct-detection experiments done on the surface and the Figure 11: Discovery reach (thick red dashed lines) for a silicon dark matter detector with singleelectron sensitivity on a balloon (satellite) assuming an exposure of 1 gram-hour (0.1 gram-month) and 10 6 (10 9 ) background events, together with constraints on dark matter interacting with a massive, ultralight dark photon.…”

“…At even higher masses (m χ ≥ 1 GeV), we use data from a high-altitude nuclear recoil experiments labelled "RRS" to constrain the open parameter space between the upper boundary of the direct-detection experiments done on the surface and the Figure 11: Discovery reach (thick red dashed lines) for a silicon dark matter detector with singleelectron sensitivity on a balloon (satellite) assuming an exposure of 1 gram-hour (0.1 gram-month) and 10 6 (10 9 ) background events, together with constraints on dark matter interacting with a massive, ultralight dark photon. Also shown are cooling constraints from supernovae 1987A (brown, "SN") [66], as well as Red-Giant and Horizontal-Branch stars (brown, "RG&HB") [62]; constraints from measurements of the number of relativistic degrees of freedom from the CMB (light green, "CMB N eff ") and BBN (blue, "BBN N eff ") [64,100], and from searches for milli-charged particles at SLAC (purple, "SLAC") [67], colliders (blue, "COLL") [62,104], and at LSND and MiniBooNE (green, "neutrino experiments") [68]; and the direct-detection constraints derived in this paper from SENSEI, CDMS-HVeV, XENON10, XENON100, and DarkSide-50 (combined into one red-shaded region, labelled "direct detection"), as well as from RRS (purple) and XQC (light orange) [45]. We also show for comparison the "freeze-in" line along which DM obtains the correct relic density in this model [4,105].…”

Novel Direct Detection Constraints on Light Dark Matter

“…Solid (dashed) lines assume a CR density that equals, on average, the local value out to a distance of 1 kpc (10 kpc). We compare our limits to those deriving from CMB observations [40], gas cloud cooling [38], the X-ray Quantum Calorimeter experiment (XQC) [39], and a selection of direct detection experiments [43][44][45] after taking into account the absorption of DM in soil and atmosphere [33].…”