Is the dark matter particle its own antiparticle?

TL;DR

This paper proposes a method using direct detection data to determine whether dark matter particles are their own antiparticles, which could significantly advance understanding of dark matter's fundamental nature.

Contribution

It introduces a novel test based on measuring spin-independent cross sections across three nuclei to distinguish self-conjugate from non-self-conjugate dark matter.

Findings

Feasible with future precise measurements

Applicable to specific target nuclei combinations

Potential to confirm dark matter as its own antiparticle

Abstract

We propose a test based on direct detection data that allows to determine if the dark matter particle is different from its antiparticle. The test requires the precise measurement of the dark matter spin-independent direct detection cross sections off $\mathrm{three}$ different nuclei, and consists of interpreting such signals in terms of self-conjugate (particle $=$ antiparticle) dark matter to see if such interpretation is consistent. If it is not, the dark matter must be different from its antiparticle. We illustrate this procedure for two sets of target nuclei, $\mathrm{\{Xe, Ar, Si\}}$ and $\mathrm{\{Xe, Ar, Ge\}}$, identifying the regions of the parameter space where it is particularly feasible. Our results indicate that future signals in direct detection experiments, if sufficiently accurate, might be used to establish that the dark matter particle is not its own antiparticle --a major step towards the determination of the fundamental nature of the dark matter.