Constraints from a many-body method on spin-independent dark matter scattering off electrons using data from germanium and xenon detectors

Mukesh K Pandey,C.-P Liu,Jiunn-Wei Chen,Chung-Chun Hsieh,Henry T Wong,Lakhwinder Singh,Chih-Pan Wu,Hsin-Chang Chi

doi:10.1103/physrevd.102.123025

Abstract

Scattering of light dark matter (LDM) particles with atomic electrons is studied in the context of effective field theory. Contact and long-range interactions between dark matter and an electron are both considered. A state-of-the-art many-body method is used to evaluate the spin-independent atomic ionization cross sections of LDM-electron scattering, with an estimated error about 20%. New upper limits are derived on parameter space spanned by LDM mass and effective coupling strengths using data from the CDMSlite, XENON10, XENON100, and XENON1T experiments. Comparison with existing calculations shows the importance of atomic structure. Two aspects particularly important are relativistic effect for inner-shell ionization and final-state free electron wave function which sensitively depends on the underlying atomic approaches.

Highlights

Astronomical and cosmological observations provide evidences of dark matter (DM) and point out its properties such as nonrelativistic (NR), nonbaryonic, stable with respect to cosmological time scale, and interacting weakly, if any, with the standard model (SM) particles
Scattering of light dark matter (LDM) particles with atomic electrons is studied in the context of effective field theory
Two aspects important are relativistic effect for inner-shell ionization and finalstate free electron wave function which sensitively depends on the underlying atomic approaches

Summary

INTRODUCTION

Astronomical and cosmological observations provide evidences of dark matter (DM) and point out its properties such as nonrelativistic (NR), nonbaryonic, stable with respect to cosmological time scale, and interacting weakly, if any, with the standard model (SM) particles. This motivates searches of DM particles with masses lighter than generic WIMPs, i.e., ≲10 GeV=c2 Such light dark matter (LDM) candidates arise in many well-motivated models, and to account for the relic DM abundance, there are mechanisms suggesting LDM interacts with SM particles through light or heavy mediators with coupling strengths smaller than the weak scale Current low-threshold experiments sensitive to sub-keV nuclear recoil, such as CoGENT [11,12,13] and CDEX [14,15,16], can only search for DM particles with masses as low as a few GeV through DM-nucleus interactions.

FORMALISM

RESULTS AND DISCUSSIONS

SUMMARY