Leveraging the FCC-ee capabilities to study the invisible decay of a dark photon

by Amin Abouibrahim

Tuesday 23 Jun 2026, 15:30 → 16:30 US/Eastern

Large Seminar Room

 The search for dark sectors remains one of the most compelling frontiers in particle physics, with dark photons providing a well-motivated portal between the Standard Model and hidden degrees of freedom. In this colloquium, we explore the prospects for probing the invisible decays of dark photons at the Future Circular Collider (FCC-ee), emphasizing how its clean experimental environment enables qualitatively new approaches to reconstructing invisible final states. We contrast these capabilities with those of the Large Hadron Collider, where searches for invisibly decaying particles rely primarily on missing transverse momentum in a complex hadronic environment. While the LHC benefits from higher center-of-mass energy and large production rates, the presence of QCD backgrounds and underlying event activity limits the precision with which invisible final states can be reconstructed and interpreted. In contrast, FCC-ee offers a precisely known initial state, negligible pile-up, and superior detector resolution, allowing for the use of recoil-mass techniques enabling model-independent measurements of invisible decay channels with unprecedented sensitivity.

We present projected sensitivities demonstrating that FCC-ee can significantly extend the reach for dark photon parameter space, particularly in regions inaccessible to current hadron collider searches. The complementarity between the LHC and FCC-ee highlights the importance of a diversified experimental program: while the LHC explores high-energy frontiers, FCC-ee provides precision tools essential for uncovering subtle signals of new physics in invisible channels. This synergy will be crucial in advancing our understanding of dark sectors and their connection to the Standard Model.

 

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