Model-independent Analyses of Dark-Matter Particle Interactions

TL;DR

This paper develops a comprehensive, model-independent framework for analyzing dark matter particle interactions with nuclei, revealing six nuclear response functions and showing experiments are more sensitive to certain velocity-dependent interactions than previously thought.

Contribution

It introduces the most general low-energy WIMP-nucleon interaction framework, expanding beyond the traditional spin-independent/spin-dependent models.

Findings

Current experiments are four orders of magnitude more sensitive to derivative couplings.

The cross section includes six independent nuclear response functions.

Velocity-dependent interactions are more detectable than previously estimated.

Abstract

A model-independent treatment of dark-matter particle elastic scattering has been developed, yielding the most general interaction for WIMP-nucleon low-energy scattering, and the resulting amplitude has been embedded in the nucleus, taking into account the selection rules imposed by parity and time-reversal. One finds that, in contrast to the usual spin-independent/spin-dependent (SI/SD) formulation, the resulting cross section contains six independent nuclear response functions, three of which are associated with possible velocity-dependent interactions. We find that current experiments are four orders of magnitude more sensitive to derivative couplings than is apparent in the standard SI/SD treatment, which necessarily associates such interactions with cross sections proportional to the square of the WIMP velocity relative to the nuclear center of mass.