FCC-ee and the high-energy physics landscape

FCC-ee, a future electron–positron collider, is the first step in a future collider program aiming to improve our understanding of high-energy physics and ultimately go beyond the Standard Model. The Standard Model provides a remarkably accurate description of the laws of physics over an enormous range of distance and energy scales. However, there are aspects of the world around us that it does not explain, including the nature of dark matter and the absence of antimatter in the observed universe. The Standard Model presents theoretical puzzles, such as unexplained hierarchies and patterns of masses and mixings, as well as theoretical opportunities, in the form of portals that may access as-yet-undiscovered dark or hidden sectors. This essay explains how these physics considerations motivate FCC-ee, which will provide a flexible, powerful probe of physics at the electroweak scale and offer the potential to discover rare processes related to dark matter or otherwise hidden physics. It also situates FCC-ee in the context of other planned experiments, including its successor FCC-hh. The FCC physics program as a whole provides a roadmap for the future of particle physics extending well into the twenty-first century.