A Search for Ultra-Light Vector Dark Matter with a Rotating Torsion Balance

We search for ultra-light vector dark matter interacting with a rotating torsion balance with a baryon minus lepton number composition dipole. Our search spans candidate masses in the ultra-low mass range from 1.3~$\times {10}^{-22}$ to 1.9~$\times {10}^{-18}$ eV. We set limits on the coupling strength to baryon minus lepton number for each dark matter candidate reaching a peak sensitivity of $g_{B-L}\le 9\times {10}^{-26}$.