The FCC-ee in a few words

The idea of a large circular e+e- collider as Higgs Factory came from a conjunction of circumstances: i) the need of a large tunnel for the continuation of the high energy exploration after the LHC; ii) the new ‘nano-beam’ designs proposed for the ‘super’ B factories; iii) and of course the discovery of the Higgs boson with a mass that could have been reached (with efforts) at LEPII. The idea of such a machine as a first step toward a 100TeV pp collider was submitted to the ESPP2013/13 and led to the FCC study, launched in 2014. The study concluded in its FCC-int submission to the ESPP2020 that the “The most effective and comprehensive approach to thoroughly explore the open questions in modern particle physics is a staged research programme, integrating in sequence lepton (FCC-ee) and hadron (FCC-hh) collisions”.

The ESPP concluded: “Europe, together with its international partners, should investigate the technical and financial feasibility of a future hadron collider at CERN with a centre-of-mass energy of at least 100 TeV and with an electron-positron Higgs and electroweak factory as a possible first stage. Such a feasibility study of the colliders and related infrastructure should be established as a global endeavour and be completed on the timescale of the next Strategy update.”

The FCC-ee is a high-luminosity, high-precision e+e- circular collider. Two separate e+ and e- storage rings with very strong focusing, fed by a full size continuous injector, provide e+e- collision luminosities ranging from (per interaction point) 230 1034 /cm2 /s at the Z pole, 8 1034 /cm2 /s at the ZH production maximum (240 GeV) and 1.7 1034 /cm2 /s at the tt threshold and up to 365 GeV. Two to four interaction points are considered. The run plan of 15-20 years yields 5 1012 Z bosons, 108 W pairs, 1.3 106 Higgs bosons and 106 top quark pairs. Thanks to the availability of transverse polarization, the energy calibration at 100 keV precision offers unprecedented precision for measurements of Z and W properties. The possibility of s-channel Higgs production at ECM=125 GeV is under study, giving unique access to the electron Yukawa coupling. These opportunities make the FCC-ee stand out among the other Higgs factory proposals. Especially at the Z run, considerable challenges await experimenters and theorists, for systematic uncertainties to match the extraordinary available statistical precision.

Following the ESPP 2020 recommendations, the goal until 2025 of the Physics Experiments and Detector studies will be, with widest participation from the international community, the delivery of an advanced CDR demonstrating the breath and feasibility of the experimental program, including detector designs. The present focus on the experimental side is the analysis of physics benchmark measurements with the aim of producing a consistent set of detector requirements, under the aegis of the Physics Performance Coordination. The design of the detectors, the use of the latest technologies, and the R&D program, offer great opportunities for creativity. On the phenomenological side, focus will be the full understanding of the possibilities for discovery of the machine, as well as the planning of the precision calculations required to fully exploit the program of precision measurements.

To learn more about the current challenges, use the "Contact/Join Us" button (top-right corner of this page) to join the FCC PED Feasibility Study, subscribe to PED mailing lists, and collaborate with us! “Europe and International Partners” all welcome.

Next events

FCC-ee Beam Energy Calibration, Polarisation, Monochromatisation

General Software Meetings
- CERN - 4/S-030

- Zoom


FCC-ee Machine-Detector Interface


First piece of hardware for the FCC-ee

A prototype for the final focussing quadrupole of the FCC-ee was 3D-printed over Xmas, for tests and measurements. Congratulations to Mike Koratzinos and magnet group for this achievement.

Machine's potential once again enhanced

FCC-ee could measure the top quark electroweak couplings with unprecedented precision through the top pair production in semileptonic decays. Check the paper here

Societé Française de Physique supports FCCs

The Fields and Particles division of the "Societé Française de Physique" encourages the study of an e+e- collider to measure the Higgs, top, Z and W properties. Check the conclusions delivered after the "Journée: Futur de la Physique des particules", at LPNHE, Paris, and Patrick Janot's FCC talk in this context. 

Clear and concise!

Terry Wyatt supported a very clear physics case for an e+e- 90-350(500) GeV collider during his talk on the overview of the European Strategy for Particle Physics, at UK HEP Forum 2015. Check his talk here.


Academic Training lecture: Perspective for a future circular collider, FCC-ee

Check out the slides and the recording of this lively lecture here.

Article in the CERN Courrier

The FCC-ee mini-workshop on the strong coupling constant (alpha_s) is featured in the CERN Courrier and in the CERN/PH news this month ! You can browse the very interesting presentations in the corresponding indico agenda.

FCC Week 2015 is over

The first annual meeting of this visionary study marked a milestone of the first exploratory study phase. 340 participants and 290 contributions from all domains of the study gave impressive evidence of the progress achieved and the challenges ahead. 

FCC Weeek 2015

One year after the FCC kick-off meeting, the first annual meeting of the Future Circular Collider study is taking place in Washington on the 23rd-27th March. The purpose is to conclude the first exploratory phase and identify the baseline for the further study. Don't miss this very important milestone!


New physics conveners

Ayres Freitas (Precision Calculations), Matthew McCullough (BSM Models) and Freya Blekmann (Top-quark properties) have joined the physics coordination group. Welcome Freya, Ayres and Matthew!

FCC-ee featured in Spanish and French main media

The FCC-ee concept drew the attention of two of the main high-circulation newspapers in Spain and France. Read the articles that appeared in El Pais and Le Monde (p. 5). 

CERN's Director for Accelerators and Technology talks about FCC

Frederick Bordry will introduce the general public to the feasibility of designing, building and operating the FCC, as well as the different machine options (hh,ee,he), at the CERN Globe on the 11th March. Registration is mandatory here.

Happy birthday FCC-ee!

Three years ago today, we submitted our first paper on A High Luminosity e+e- Collider in the LHC tunnel to study the Higgs Boson. The numbers have changed, but our ambitious spirit remains the same. May you have many more, FCC-ee!