A torsion-balance search for ultra low-mass bosonic dark matter
  We used a stationary torsion balance with a beryllium-aluminum composition
dipole to search for ultra low-mass bosonic dark matter coupled to baryon minus
lepton number. We set 95% confidence limits on the coupling constant $g_{\rm
B-L}$ for bosons with masses between $10^{-18}$ and $10^{-16}$ eV/$c^2$ with
the best performance at $m_{\rm DM} = 8\times 10^{-18}$ eV/$c^2$ constraining
$g_{B-L}(\hbar c)^{-1/2} < 1 \times 10^{-25}$. This provides a complimentary
limit to equivalence-principle experiments that search for ultra low-mass
bosons as force-mediating particles.
