https://doi.org/10.1140/epjp/s13360-021-01874-2
Review
Direct discovery of new light states at the FCCee
1
CERN, Theoretical Physics Department, Geneva, Switzerland
2
School of Physics, The University of Melbourne, 3010, Victoria, Australia
Received:
16
April
2021
Accepted:
14
August
2021
Published online:
14
September
2021
Light new states are ubiquitous in many models that address fundamental outstanding questions within the standard model (SM). The FCCee provides an excellent opportunity to probe these new particles with masses between 1 and 
GeV and their electroweak couplings. Here we discuss the theory motivations for axion-like particles and heavy neutral leptons and detail the potential of direct discovery at the FCCee. We highlight that our current understanding requires light new states to be embedded within a bigger theory framework and thus the complementarity of the precision frontier at the FCCee and the high energy frontier of the FCChh program.
The original online version of this article was revised to add additional funding information.
A correction to this article is available online at https://doi.org/10.1140/epjp/s13360-022-02959-2.
Copyright comment corrected publication 2022
© Crown 2021. corrected publication 2022
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