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Probing the Dark Matter EFT with QUEST-DMC: Projected Sensitivities and Attenuation Ceilings

QUEST-DMC Collaboration, :, N. Darvishi, S. Autti, L. Bloomfield, A. Casey, N. Eng, P. Franchini, R. P. Haley, P. J. Heikkinen, A. Jennings, A. Kemp, E. Leason, J. March-Russell, A. Mayer, J. Monroe, D. Munstermann, M. T. Noble, J. R. Prance, X. Rojas, T. Salmon, J. Saunders, J. Smirnov, R. Smith, M. D. Thompson, A. Thomson, A. Ting, V. Tsepelin, S. M. West, L. Whitehead, D. E. Zmeev

Abstract

This proceedings contribution summarises projected constraints from the QUEST-DMC concept, a surface-based direct-detection experiment using superfluid $^3$He operated below the millikelvin regime and instrumented with nanomechanical resonators read out by SQUIDs. The low recoil-energy threshold (down to sub-eV for the SQUID configuration) enables sensitivity to sub-GeV dark matter across a wide set of interaction structures beyond the canonical spin-independent and spin-dependent limits. We present projections in the non-relativistic Effective Field Theory (EFT) framework, scanning the standard set of fourteen Galilean-invariant operators and expressing reach in terms of effective dark matter-nucleon (or dark matter-neutron) cross sections. Because QUEST-DMC operates at the surface, we also account for suppression of the incident flux due to scattering in the atmosphere and Earth, which produces an interaction-dependent sensitivity ceiling at large couplings. Finally, we outline how the non-relativistic results map onto representative relativistic EFT dark matter-nucleon bilinears, enabling a compact interpretation of the projected reach in terms of UV-motivated coupling structures.

Probing the Dark Matter EFT with QUEST-DMC: Projected Sensitivities and Attenuation Ceilings

Abstract

This proceedings contribution summarises projected constraints from the QUEST-DMC concept, a surface-based direct-detection experiment using superfluid He operated below the millikelvin regime and instrumented with nanomechanical resonators read out by SQUIDs. The low recoil-energy threshold (down to sub-eV for the SQUID configuration) enables sensitivity to sub-GeV dark matter across a wide set of interaction structures beyond the canonical spin-independent and spin-dependent limits. We present projections in the non-relativistic Effective Field Theory (EFT) framework, scanning the standard set of fourteen Galilean-invariant operators and expressing reach in terms of effective dark matter-nucleon (or dark matter-neutron) cross sections. Because QUEST-DMC operates at the surface, we also account for suppression of the incident flux due to scattering in the atmosphere and Earth, which produces an interaction-dependent sensitivity ceiling at large couplings. Finally, we outline how the non-relativistic results map onto representative relativistic EFT dark matter-nucleon bilinears, enabling a compact interpretation of the projected reach in terms of UV-motivated coupling structures.
Paper Structure (4 sections, 6 equations, 3 figures, 1 table)

This paper contains 4 sections, 6 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. NREFT Ingredients for $^3$He and Mapping to Relativistic EFT Couplings
  3. Projected NREFT Sensitivity, Attenuation Ceilings, and Relativistic Interpretation
  4. Conclusions

Figures (3)

  • Figure 1: The QUEST-DMC 90% C.L. limits on the cross-section for velocity- and momentum-independent operators $\mathcal{O}_4$ (SD, left) and $\mathcal{O}_1$ (SI, right), compared to existing limits from Xenon 1T S2-only MIGD XENON:2019zpr, CRESST III (LiAlO$_2$) CRESST_2022, LUX LUXSD_2016, CDMSlite CDMSLite_2018, PandaX-II PandaX-II:2018woa and EDELWEISS EDELWEISS:2019vjv for SD, and from DarkSide-50 DarkSide-50:2022qzh, XENON1T XENON:2018voc, and EDELWEISS EDELWEISS:2019vjv for SI. The upper limit sensitivity is shown for the straight-line (SL) path and diffusive (Diff) propagation treatments, depicted in red and black, respectively. Dashed (dotted) lines correspond to SQUID-based (conventional) readout.
  • Figure 2: Overview of the collective cross-section range probed for the analysed NREFT operators in the SQUID-based QUEST-DMC configuration, shown as the span between the lowest projected sensitivity (floor) and the highest excluded value set by attenuation (ceiling). The summary illustrates the breadth of EFT parameter space covered by QUEST-DMC in the low-mass regime, and enables compact comparison to representative existing limits (e.g. Xenon 1T S2-only MIGD XENON:2019zpr and EDELWEISS EDELWEISS:2019vjv, depending on interaction type).
  • Figure 3: Effective coupling ranges for dark matter-nucleon and -neutron interactions, grouped by their underlying relativistic bilinear types (SS, TS, AA, etc.) as defined by the relativistic to non-relativistic mapping in Table \ref{['tab:DM_mapping_all']}. The couplings represent rescaled Wilson coefficients derived from the QUEST-DMC SQUID-based sensitivity projections. The vertical dashed line with right-pointing arrows indicates the region above the unitarity limit.