Can we determine the particle/antiparticle nature of Dark Matter?
Bradley J. Kavanagh
GRAPPA institute, University of Amsterdam
Roberto A. Lineros
What can we learn about the properties of Dark Matter (DM) in the years after it is discovered? Which detectors and search strategies should we pursue to learn the most about its nature? I will briefly discuss some proposals for extracting the DM mass, speed distribution and interaction Lagrangian from a future discovery. I will then focus on one particular question: “Is Dark Matter its own antiparticle?” If the DM is Dirac-like, DM particles and antiparticles may have different couplings to protons and neutrons, which would lead to a peculiar scaling of the direct detection rate across different target materials. For a number of proposed direct detection experiments due to be taking data during the period 2020-2025, we explore the prospects of discriminating between Dirac-like and Majorana-like DM using this effect. For the benchmarks we consider, we find that the two scenarios can typically be discriminated at around the 3-sigma level (depending on the underlying couplings). Crucially, if Silicon-based detectors are used (in addition to the usual ton-scale Xenon and Argon experiments), 5-sigma discrimination may be possible, over a wider range of the parameter space than when using Germanium or Calcium Tungstate detectors. This result shows that the particle/antiparticle nature of DM may be revealed with a future direct detection signal. It also acts as a guide for which detectors should be pursued in order to get the most out of a future DM discovery.