The physics case for electron-positron beams at the Future Circular Collider (FCC-ee) is succinctly summarized. The FCC-ee core program involves $e^+e^-$ collisions at $\sqrt{ s}$ = 90, 160, 240, and 350 GeV with multi-ab$^{ -1}$ integrated luminosities, yielding about 10$^{ 12}$ Z bosons, 10$^{ 8}$ W$^+$W$^-$ pairs, 10$^{ 6}$ Higgs bosons and 4$\cdot$10$^{ 5}$ $t\bar{ t}$ pairs per year. The huge luminosities combined with $\cal{ 100}$ keV knowledge of the c.m. energy will allow for Standard Model studies at unrivaled precision. Indirect constraints on new physics can thereby be placed up to scales $\Lambda_{ _{ \rm NP}} \approx$ 7 and 100 TeV for particles coupling respectively to the Higgs and electroweak bosons.
Categories: hep-ex hep-ph