Probing dark matter using free leptons: PKMUON

We propose a new method to detect sub-GeV dark matter, through their scatterings from free leptons and the resulting kinematic shifts. Especially, such an experiment can detect dark matter interacting solely with muons. The experiment proposed here is for directly probing the muonphilic dark matter in a model-independent way. Its complementarity with the muon on the target proposal is similar to e.g. XENON/PandaX and ATLAS/CMS on the dark matter searches. Moreover, our proposal can work better for relatively heavy dark matter such as those in the sub-GeV region. We start with a small device of a size around 0.1-1m, using atmospheric muons to set up a prototype. Within only one year of operation, the sensitivity on the cross-section of dark matter scattering with muons can already reach sigma D similar to 10-19(-20,-18)cm2 for the dark matter mass MD=100 (10, 1000)MeV. We can then interface the device with a high-intensity muon beam of 1012/bunch. Within one year, the sensitivity can reach sigma D similar to 10-27(-28,-26)cm2 for MD=100 (10,1000)MeV.