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