A Search for Low-mass Dark Matter via Bremsstrahlung Radiation and the Migdal Effect in SuperCDMS

TL;DR

This paper introduces a novel analysis method for SuperCDMS data to search for low-mass dark matter particles via bremsstrahlung radiation and the Migdal effect, extending detection sensitivity to sub-GeV masses.

Contribution

It presents the first application of a profile likelihood framework to these inelastic channels, setting new limits on low-mass dark matter detection.

Findings

Excluded dark matter masses down to 220 MeV/c^2 via bremsstrahlung.

Excluded dark matter masses down to 30 MeV/c^2 via the Migdal effect.

Set upper limits on dark matter-nucleon cross sections.

Abstract

We present a new analysis of previously published of SuperCDMS data using a profile likelihood framework to search for sub-GeV dark matter (DM) particles through two inelastic scattering channels: bremsstrahlung radiation and the Migdal effect. By considering these possible inelastic scattering channels, experimental sensitivity can be extended to DM masses that are undetectable through the DM-nucleon elastic scattering channel, given the energy threshold of current experiments. We exclude DM masses down to $220~\textrm{MeV}/c^2$ at $2.7 \times 10^{-30}~\textrm{cm}^2$ via the bremsstrahlung channel. The Migdal channel search provides overall considerably more stringent limits and excludes DM masses down to $30~\textrm{MeV}/c^2$ at $5.0 \times 10^{-30}~\textrm{cm}^2$.