LAUSR

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 B − L for bosons with masses between 10 − 18 and 10 − 16 eV/ c 2 with the best performance at m DM = 8 × 10 − 18 eV/ c 2 constraining g B − L (¯ hc ) − 1 / 2 < 1 × 10 − 25 . This provides a complimentary limit to equivalence-principle experiments that search for ultra low-mass bosons as force-mediating particles.