Probing spin-dependent dark matter interactions with $^6$Li

TL;DR

This paper explores the use of $^6$Li in dark matter detection, demonstrating that including this isotope significantly enhances sensitivity to spin-dependent interactions, especially for low-mass dark matter particles.

Contribution

It introduces new nuclear matrix element calculations for $^6$Li and shows how incorporating this isotope improves detection limits in existing data.

Findings

Including $^6$Li improves detection limits for spin-dependent interactions by over two orders of magnitude for dark matter masses below 1 GeV/c$^2$.

Using $^6$Li enhances the sensitivity of CRESST to low-mass dark matter particles.

The study demonstrates the potential of specific nuclides in existing detectors to significantly advance dark matter searches.

Abstract

CRESST is one of the most prominent direct detection experiments for dark matter particles with sub-GeV/c$^2$ mass. One of the advantages of the CRESST experiment is the possibility to include a large variety of nuclides in the target material used to probe dark matter interactions. In this work, we discuss in particular the interactions of dark matter particles with protons and neutrons of $^{6}$Li. This is now possible thanks to new calculations on nuclear matrix elements of this specific isotope of Li. To show the potential of using this particular nuclide for probing dark matter interactions, we used the data collected previously by a CRESST prototype based on LiAlO$_2$ and operated in an above ground test-facility at Max-Planck-Institut f\"ur Physik in Munich, Germany. In particular, the inclusion of $^{6}$Li in the limit calculation drastically improves the result obtained for spin-dependent interactions with neutrons in the whole mass range. The improvement is significant, greater than two order of magnitude for dark matter masses below 1 GeV/c$^2$, compared to the limit previously published with the same data.