Compute electron-recoil direct-detection rates

Determine the electron-ionisation rate and corresponding atomic response functions for dark-matter electron scattering in leptophilic scalar dark matter detectors, thereby extending the analysis beyond nuclear recoils.

Background

The leptophilic scalar dark matter model permits tree-level scattering of the dark matter particle from electrons through t-channel exchange of the vector-like fermion mediator. Unlike nuclear recoils, interpreting this process in a detector requires calculating electron-ionisation signals in the detector material and the associated atomic response functions. The paper does not perform this calculation and consequently treats its direct-detection constraints as conservative.

References

While this provides an additional direct-detection channel, its treatment requires a dedicated calculation of the electron-ionisation rate in the detector material , including the corresponding atomic response functions; we therefore leave the analysis of electron recoils for future work and understand the constraints from direct detection as conservative.

— Probing Leptophilic Scalar Dark Matter with SMEFT and Direct Detection  (2610.26512 - Biondini et al., 19 Oct 2026) in Section 4.1, Direct Detection