Quantum Monte Carlo calculations of dark matter scattering off light nuclei
We compute the matrix elements for elastic scattering of dark matter (DM) particles off light nuclei ($^2$H, $^3$H, $^3$He, $^4$He and $^6$Li) using quantum Monte Carlo methods. We focus on scalar-mediated DM-nucleus interactions and use scalar currents obtained to next-to-leading order in chiral effective theory. The nuclear ground states are obtained from a phenomenological nuclear Hamiltonian that includes the Argonne $v_{18}$ two-body interaction and the three-body Urbana IX interaction. Within this approach, we study the impact of one- and two-body currents and discuss the size of nuclear uncertainties, including for the first time two-body effects in $A=4$ and $A=6$ systems. Our results provide the nuclear structure input needed to assess the sensitivity of future experimental searches of (light) dark matter using light nuclei, such as $^3$He and $^4$He.