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

We summarize the physics case for the International Linear Collider (ILC). We review the key motivations for the ILC presented in the literature, updating the projected measurement uncertainties for the ILC experiments in accord with the expected schedule of operation of the accelerator and the results of the most recent simulation studies.