Direct detection of sub-GeV dark matter

Abstract

Direct detection strategies are proposed for dark matter particles with MeV to GeV mass. In this largely unexplored mass range, dark matter scattering with electrons can cause single-electron ionization signals, which are detectable with current technology. Ultraviolet photons, individual ions, and heat are interesting alternative signals. Focusing on ionization, we calculate the expected dark matter scattering rates and estimate the sensitivity of possible experiments. Backgrounds that may be relevant are discussed. Theoretically interesting models can be probed with existing technologies, and may even be within reach using ongoing direct detection experiments. Significant improvements in sensitivity should be possible with dedicated experiments, opening up a window to new regions in dark matter parameter space.

Constraining light dark matter with diffuse X-ray and gamma-ray observations

“…A large class of models can accommodate DM with sub-GeV masses, see, e.g., [1][2][3][4][5][6][7][8][9]. Such DM can be probed at colliders [10][11][12][13][14][15], at direct detection experiments [9,16,17], and at proton-and electron-beam dumps [18][19][20][21][22][23].…”

“…Such DM can be probed at colliders [10][11][12][13][14][15], at direct detection experiments [9,16,17], and at proton-and electron-beam dumps [18][19][20][21][22][23]. Constraints from the Cosmic Microwave Background (CMB) already limit the s-wave DM annihilation cross section to SM matter to be below that of a thermal WIMP, for DM masses below ∼ 7 GeV [24][25][26][27].…”

Direct detection portals for self-interacting dark matter

“…[81], for an appropriate choice of q, with little dependence on astrophysical halo properties considered therein. It is also useful to consider the direct detection cross section for DM scattering on electrons, which was proposed as an avenue for detecting sub-GeV DM [56,57]. The SI cross section is…”

“…The current limits from XENON10 are shown by the long dashed curve for ε γ = 10 −4 . (For such large values of ε γ , the m X 1 GeV region is strongly exluded by direct detection via nuclear recoils [56].) Our final benchmark model is symmetric SIDM with a scalar mediator coupled via Higgs mixing, shown in Fig.…”

“…Tests for self-interactions within large DM halos, such as in merging clusters [53,54] or halo shape observables [55], are most sensitive to DM masses m X 10 GeV where the self-interaction cross section tends to be more velocity-independent. We also note that direct detection experiments can also probe low mass SIDM as well, via electron recoils [56,57], although the effective reach in couplings is much reduced compared to nuclear recoils.…”