HEP Seminar: Monday, Sept 28, 2020 - Searching for Dark Matter in the Inelastic Regime

Event Date: 

Monday, September 28, 2020 - 12:00pm

Event Location: 

  • Zoom
  • HEP Seminar

Dan Baxter, University of Chicago

Searching for Dark Matter in the Inelastic Regime

In direct detection experiments, interpreting an observed rate as a limit

on (or detection of) dark matter requires assumptions about the type of

interaction. Typically, this breaks down as elastic nuclear scattering

(for energies >1 keV) or electron scattering (for energies 1-50 eV). The

first challenge to this conventional way of thinking came in the form of

the Migdal effect, wherein a sub-threshold nuclear recoil produces some

amount of detectable ionization due to coupling between the scattered

nucleus and atomic system. I will demonstrate how this inelastic channel

could be the dominant interaction channel for dark matter masses between

0.1-1 GeV. I will also show how, in semiconductors, this effect may be

superseded by inelastic collective effects, such as plasmon resonance,

which cannot be described by single particle wavefunctions. Both of these

new inelastic channels have the potential to amplify the sensitivity of

existing (and future) detectors to dark matter, but have large theoretical

uncertainties which need to be calibrated in order to fully understand

their impact.