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The International Linear Collider (ILC) is on the table now as a new global energyfrontier accelerator laboratory taking data in the 2030's. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community.

The discrepancies between b → s + − data and the corresponding Standard Model predictions constitute the most significant hints for new physics (at the TeV scale or below) currently available. In fact, many scenarios that can account for these anomalies have been proposed in the literature. However, only a single light new physics explanation, i.e. with a mass below the B meson scale, is possible: a light Z boson. In this article, we point out that improved limits on B → K ( * ) νν, including the experimental sensitivities required for a proper treatment of the necessarily sizeable Z width, together with the forthcoming Belle II analyses of e + e − → µ + µ − + invisible, can rule out a Z explanation of b → s + − data with a mass below ≈ 4 GeV. Importantly, such a light Z is the only viable single particle solution to the b → s + − anomalies predicting R(K ( * ) ) > 0 in high q 2 bins, therefore providing an essential consistency test of data.

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Charged lepton flavor violation is an unambiguous signature for New Physics.Here we present a summary of the theoretical and experimental status of the search for charged lepton flavor violation in heavy particle decays, in particular in the decays of the Z and Higgs bosons, and of the top quark. Decays of beyond-Standard-Model particles such as a Z or an additional scalar particle are also discussed. Finally the prospects for such searches at proposed future electron-positron colliders are reviewed.