Ab initio structure factors for spin-dependent dark matter direct detection

TL;DR

This paper provides comprehensive ab initio calculations of structure factors for spin-dependent dark matter interactions with various nuclei, improving accuracy and convergence in nuclear response modeling for direct detection experiments.

Contribution

It introduces a consistent framework combining chiral effective field theory, in-medium similarity renormalization group, and natural orbitals to compute nuclear structure factors for dark matter detection.

Findings

Converged structure factors for multiple nuclei used in dark matter searches.

Identification of uncertainties, especially in iodine-127, indicating areas for further research.

Validation of results with previous calculations, confirming overall reliability.

Abstract

We present converged ab initio calculations of structure factors for elastic spin-dependent WIMP scattering off all nuclei used in dark matter direct-detection searches: $^{19}$F, $^{23}$Na, $^{27}$Al, $^{29}$Si, $^{73}$Ge, $^{127}$I, and $^{129,131}$Xe. From a set of established two- and three-nucleon interactions derived within chiral effective field theory, we construct consistent WIMP-nucleon currents at the one-body level, including effects from axial-vector two-body currents. We then apply the in-medium similarity renormalization group to construct effective valence-space Hamiltonians and consistently transformed operators of nuclear responses. Combining the recent advances of natural orbitals with three-nucleon forces expressed in large spaces, we obtain basis-space converged structure factors even in heavy nuclei. Generally results are consistent with previous calculations, but large uncertainties in $^{127}$I highlight the need for further study.