Predicted modulated differential rates for direct WIMP searches at low energy transfers

TL;DR

This paper analyzes the expected signals and modulation effects in direct dark matter detection experiments focusing on light WIMPs and low energy transfers, highlighting how modulation sign changes can inform WIMP mass.

Contribution

It introduces calculations of differential event rates for light WIMPs, revealing the possibility of large nucleon cross sections and sign changes in modulation amplitude.

Findings

Large nucleon cross sections are possible for light WIMPs.

Modulation amplitude can change sign depending on WIMP mass.

Maximum detection rate may occur six months later than expected.

Abstract

The differential event rate for direct detection of dark matter, both the time averaged and the modulated one due to the motion of the Earth, are discussed. The calculations focus on relatively light cold dark matter candidates (WIMP) and low energy transfers. It is shown that for sufficiently light WIMPs the extraction of relatively large nucleon cross sections is possible. Furthermore for some WIMP masses the modulation amplitude may change sign, meaning that, in such a case, the maximum rate may occur six months later than naively expected. This effect can be exploited to yield information about the mass of the dark matter candidate, if and when the observation of the modulation of the event rate is established.