Speaker
Description
Direct detection experiment data is typically interpreted in terms of a single non-relativistic effective theory (NREFT) operator, for instance liquid argon detector data is historically interpreted only in terms of spin-independent dark matter interactions due to the zero nuclear spin of argon. However, in the NREFT framework multiple operators contribute. While the contribution of the canonical SD operator O4 vanishes for argon, additional operators involving the dark matter spin remain non-zero. For sufficiently large target masses, the sum of these surviving contributions can be large enough to produce observable nuclear recoil signals.
We perform a scan over the NREFT parameter space, considering all isospin-conserving couplings of dark matter to protons and neutrons in liquid argon and liquid xenon. We then produce sensitivity projections for DarkSide-20k and LZ and show maximal enhancement and suppression arising from the additional NREFT operator contributions. The results demonstrate that, contrary to expectations, large liquid argon detectors such as DarkSide-20k can indeed probe SD dark matter models, highlighting the importance of operator-level analyses in future direct detection searches.