Dark Matter vs. Neutrinos: The effect of astrophysical uncertainties and timing information on the neutrino floor

TL;DR

This paper explores how timing and astrophysical uncertainties affect the neutrino floor in dark matter detection, proposing methods to surpass this limit using annual modulation signals.

Contribution

It demonstrates that timing information and understanding of astrophysical uncertainties can help overcome the neutrino floor in dark matter direct detection experiments.

Findings

Annual modulation can distinguish dark matter from neutrino background.

Timing information improves exclusion limits by up to an order of magnitude.

Astrophysical uncertainties widen the neutrino floor's mass range.

Abstract

Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments will run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable through a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions the neutrino floor can still be surpassed using timing information, though certain velocity streams may prove problematic.