Search for Low-Mass Dark Matter with CDMSlite Using a Profile Likelihood Fit

TL;DR

This paper reports on the final analysis of CDMSlite data using profile likelihood methods, achieving improved sensitivity and setting new upper limits on low-mass dark matter particle interactions with germanium nuclei.

Contribution

It introduces a new analysis with a different detector, employing profile likelihood and data salting to enhance dark matter detection sensitivity.

Findings

Achieved a 70 eV energy threshold.

Set an upper limit of 5.4×10⁻⁴² cm² on cross section at 5 GeV/c².

Improved sensitivity for dark matter masses between 2.5 and 10 GeV/c².

Abstract

The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) searches for interactions between dark matter particles and germanium nuclei in cryogenic detectors. The experiment has achieved a low energy threshold with improved sensitivity to low-mass (<10 GeV/c$^2$) dark matter particles. We present an analysis of the final CDMSlite data set, taken with a different detector than was used for the two previous CDMSlite data sets. This analysis includes a data "salting" method to protect against bias, improved noise discrimination, background modeling, and the use of profile likelihood methods to search for a dark matter signal in the presence of backgrounds. We achieve an energy threshold of 70 eV and significantly improve the sensitivity for dark matter particles with masses between 2.5 and 10 GeV/c$^2$ compared to previous analyses. We set an upper limit on the dark matter-nucleon scattering cross section in germanium of 5.4$\times$10$^{-42}$ cm$^2$ at 5 GeV/c$^2$, a factor of $\sim$2.5 improvement over the previous CDMSlite result.