Direct detection of dynamical dark matter

Dynamical dark matter (DDM) is an alternative framework for dark-matter physics in which the dark-matter candidate is an ensemble of constituent fields with differing masses, lifetimes, and cosmological abundances. In this framework, it is the balancing of these quantities against each other across the ensemble as a whole which ensures phenomenological viability. In this paper, we examine the prospects for the direct detection of a DDM ensemble. In particular, we study the constraints imposed by current limits from direct-detection experiments on the parameter space of DDM models, and we assess the prospects for detecting such an ensemble and distinguishing it from traditional dark-matter candidates on the basis of data from the next generation of direct-detection experiments. For concreteness, we focus primarily on the case in which elastic scattering via spin-independent interactions dominates the interaction rate between atomic nuclei and the constituent particles of the ensemble. We also briefly discuss the effects of modifying these assumptions.