Search for Invisible Decays of the Υ(1S)

We search for invisible decays of the Υ ( 1 S ) meson using a sample of 91.4 × 10 6 Υ ( 3 S ) mesons collected at the BABAR/PEP-II B factory. We select events containing the decay Υ ( 3 S ) → π + π − Υ ( 1 S ) and search for evidence of an undetectable Υ ( 1 S ) decay recoiling against the dipion system. We set an upper limit on the branching fraction B ( Υ ( 1 S ) → invisible ) < 3.0 × 10 − 4 at the 90% confidence level