3.4 Limits on the Parameters y and m χ
61
Future initiatives that could explore a still uncovered parameter space in the plane
{y, m χ } for dark matter masses below 1 GeV are all those that have sensitivity in the
plane {ε, m A } and, in addition, accelerator-based and dark matter direct detection
experiments exploiting dark matter scattering against the nucleons and/or electrons.
Accelerator-based experiments are SHiP at CERN [97], and BDX at JLab [98] and
SBND [99] at FNAL as explained below.
– BDX at JLAB the Beam Dump eXperiment (BDX) [98] is aiming to detect light
dark matter χ produced in the interaction of an intense (100 μA) 10 GeV electron
beam with a dump. The experiment is sensitive to elastic dark matter scattering
e
−
χ → e
−
χ in the detector after production in e
− Z → e
− ZA
(A
→ χχ).
– SBND is planned to be installed at the 8 GeV proton Booster Neutrino Beamline at
FNAL about 470 m downstream of the beam dump [99]. The dark matter beam is
primarily produced via pion decays out of collisions from the primary proton beam,
and identified via dark-matter-nucleon or dark-matter-electron elastic scattering
in a LAr-based detector. SBND is expected to improve upon MiniBooNE by more
than an order of magnitude with 6 × 10
20 protons-on-target.
Also dark matter direct-detection experiments with sensitivity below 1 GeV mass
contribute to this plot. These are:
– SENSEI is a direct detection experiment [104] that will be able to explore dark
matter candidates with masses in the 1 eV and few GeV range, by detecting the
signal released in dark-matter-electron scattering interactions in a fully depleted
silicon CCD. A 2-gram detector is already operating in the NUMI access tunnel [105]. A larger project (100 grams) can be deployed at SNOLAB if funding is
obtained [100].
– CRESST-II [96] uses cryogenic detectors to search for nuclear recoil events induced
by elastic scattering of dark-matter particles in CaWO 4 crystals. Because of its
low-energy threshold, the sensitivity to dark matter was extended in the sub-GeV
region. Current bounds are derived from a dataset corresponding to 52 kg live days.
– super-CDMS [101] at SNOLAB (Canada)Start mid-2021, and uses 30 kg of Germanium and Silicium detectors.
References
1. H. Merkel et al., Search at the mainz microtron for light massive Gauge Bosons relevant for
the Muon g-2 Anomaly. Phys. Rev. Lett. 112(22), 221802 (2014). arXiv:1404.5502 [hep-ex].
https://doi.org/10.1103/PhysRevLett.112.221802
2. LHCb Collaboration, R. Aaij et al., Search for A → μ + μ − Decays. Phys. Rev. Lett.
124(4), 041801 (2020). arXiv:1910.06926 [hep-ex]. https://doi.org/10.1103/PhysRevLett.
124.041801
3. CMS Collaboration, A.M. Sirunyan et al., Search for a narrow resonance decaying to a pair
of muons in proton-proton collisions at 13 TeV
61
Future initiatives that could explore a still uncovered parameter space in the plane
{y, m χ } for dark matter masses below 1 GeV are all those that have sensitivity in the
plane {ε, m A } and, in addition, accelerator-based and dark matter direct detection
experiments exploiting dark matter scattering against the nucleons and/or electrons.
Accelerator-based experiments are SHiP at CERN [97], and BDX at JLab [98] and
SBND [99] at FNAL as explained below.
– BDX at JLAB the Beam Dump eXperiment (BDX) [98] is aiming to detect light
dark matter χ produced in the interaction of an intense (100 μA) 10 GeV electron
beam with a dump. The experiment is sensitive to elastic dark matter scattering
e
−
χ → e
−
χ in the detector after production in e
− Z → e
− ZA
(A
→ χχ).
– SBND is planned to be installed at the 8 GeV proton Booster Neutrino Beamline at
FNAL about 470 m downstream of the beam dump [99]. The dark matter beam is
primarily produced via pion decays out of collisions from the primary proton beam,
and identified via dark-matter-nucleon or dark-matter-electron elastic scattering
in a LAr-based detector. SBND is expected to improve upon MiniBooNE by more
than an order of magnitude with 6 × 10
20 protons-on-target.
Also dark matter direct-detection experiments with sensitivity below 1 GeV mass
contribute to this plot. These are:
– SENSEI is a direct detection experiment [104] that will be able to explore dark
matter candidates with masses in the 1 eV and few GeV range, by detecting the
signal released in dark-matter-electron scattering interactions in a fully depleted
silicon CCD. A 2-gram detector is already operating in the NUMI access tunnel [105]. A larger project (100 grams) can be deployed at SNOLAB if funding is
obtained [100].
– CRESST-II [96] uses cryogenic detectors to search for nuclear recoil events induced
by elastic scattering of dark-matter particles in CaWO 4 crystals. Because of its
low-energy threshold, the sensitivity to dark matter was extended in the sub-GeV
region. Current bounds are derived from a dataset corresponding to 52 kg live days.
– super-CDMS [101] at SNOLAB (Canada)Start mid-2021, and uses 30 kg of Germanium and Silicium detectors.
References
1. H. Merkel et al., Search at the mainz microtron for light massive Gauge Bosons relevant for
the Muon g-2 Anomaly. Phys. Rev. Lett. 112(22), 221802 (2014). arXiv:1404.5502 [hep-ex].
https://doi.org/10.1103/PhysRevLett.112.221802
2. LHCb Collaboration, R. Aaij et al., Search for A → μ + μ − Decays. Phys. Rev. Lett.
124(4), 041801 (2020). arXiv:1910.06926 [hep-ex]. https://doi.org/10.1103/PhysRevLett.
124.041801
3. CMS Collaboration, A.M. Sirunyan et al., Search for a narrow resonance decaying to a pair
of muons in proton-proton collisions at 13 TeV