SciPost Submission Page
Physics case for low-$\sqrt{s}$ QCD studies at FCC-ee
by David d'Enterria, Pier Francesco Monni, Peter Skands, Andrii Verbytskyi
Submission summary
| Authors (as registered SciPost users): | Andrii Verbytskyi |
| Submission information | |
|---|---|
| Preprint Link: | https://arxiv.org/abs/2503.23855v2 (pdf) |
| Date submitted: | Dec. 10, 2025, 11:55 a.m. |
| Submitted by: | Andrii Verbytskyi |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Experimental, Phenomenological |
Abstract
Measurements of hadronic final states in $e^{+}e^{-}$ collisions at centre-of-mass (CM) energies below the Z peak can notably extend the FCC-ee physics reach in terms of precision quantum chromodynamics (QCD) studies. Hadronic final states can be studied over a range of hadronic energies $\sqrt{s_\mathrm{had}} \approx 20\mbox{--}80\,\mathrm{GeV}$ by exploiting events with hard initial- and final-state QED radiation (ISR/FSR) during the high-luminosity Z-pole run, as well as in dedicated short (about one month long) $e^{+}e^{-}$ runs at CM energies $\sqrt{s} \approx 40\,\mathrm{GeV}$ and $60\,\mathrm{GeV}$. Using realistic estimates and fast detector simulations, we show that data samples of about $10^{9}$ hadronic events can be collected at the FCC-ee at each of the low-CM-energy points. Such datasets can be exploited in a variety of precision QCD measurements, including studies of light-, heavy-quark and gluon jet properties, hadronic event shapes, fragmentation functions, and nonperturbative dynamics. This will offer valuable insights into strong interaction physics, complementing data from nominal FCC-ee runs at higher center-of-mass energies, $\sqrt{s} \approx 91, 160, 240,$ and $365\,\mathrm{GeV}$.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Author comments upon resubmission
in this resubmission the comments and suggestions of the referees were implemented.
Best regards,
Andrii Verbytskyi for the authors
List of changes
The text was updated as explicitly requested by the referees and described in detail in the answers to the referees. The related textual changes are:
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“the luminosity follows the standard Lorentz γL-dependence of the beam energies, namely L ∝ √s [43].” was replaced with “the luminosity follows the standard Lorentz γL-dependence driven by the beam energies[footnote: Such a dependence is approximately confirmed with the simulated collider parameters of Table 4.], namely L ∝ √s.”
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“plus 1-week of additional beam-setup time [43].” was replaced with “plus 1-week of additional beam-setup time [43], for each single CM-energy point.”
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“These preliminary studies indicate that with a 5-$\GeV$ bin width for $m(\qqbar)$” was extended with a footnote “A finer than 5-$\GeV$ binning could potentially be obtained with more sophisticated methods of event selection and kinematic reconstruction ( e.g.\ more sophisticated combinations of the kinematics information on the photon, HFS and beams”
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Other changes: updates of references for the published papers, reformulation in the acknowledgements, minor typesetting.