Flavor-resolved four-fermion probes at the FCC-ee Z pole
Abstract
The electron-positron Future Circular Collider will provide an unprecedented opportunity for precision studies at the Z pole. In addition to improving the electroweak measurements pioneered at LEP, Tera-Z statistics and modern jet flavor reconstruction could make rare, flavor-resolved final states accessible as precision observables. We study the exclusive four-body processes e+e-→ Z→ QQ̅ℓ+ℓ- with $ Q=c,\,b$ and ℓ=μ, τ as probes of flavor-specific new physics contact interactions. A fast analysis yields representative multi-TeV reaches for vector-current interactions involving bottom or charm quarks and muons or taus, providing a baseline for future detector-level studies. For charm-current interactions, the projected direct sensitivities are comparable to those obtained indirectly from electroweak precision observables. Two-dimensional fits further show that these processes retain quark-flavor information that can be poorly resolved by the renormalization-group-induced electroweak response. These results illustrate how flavor-resolved four-body Z processes can bridge the electroweak and flavor programs at FCC-ee, opening a new class of complementary precision observables.
Related
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BibTeX
@misc{iguro2026flavorresolved,
title = {{Flavor-resolved four-fermion probes at the FCC-ee $Z$ pole}},
author = {Syuhei Iguro},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.36933},
eprint = {2609.36933},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.36933},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Flavor-resolved four-fermion probes at the FCC-ee Z pole
AU - Syuhei Iguro
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.36933
UR - https://arxiv.org/abs/2609.36933
AB - The electron-positron Future Circular Collider will provide an unprecedented opportunity for precision studies at the Z pole. In addition to improving the electroweak measurements pioneered at LEP, Tera-Z statistics and modern jet flavor reconstruction could make rare, flavor-resolved final states accessible as precision observables. We study the exclusive four-body processes e^+e^-→ Z→ QQ̅ℓ^+ℓ^- with $ Q=c,\,b$ and ℓ=μ, τ as probes of flavor-specific new physics contact interactions. A fast analysis yields representative multi-TeV reaches for vector-current interactions involving bottom or charm quarks and muons or taus, providing a baseline for future detector-level studies. For charm-current interactions, the projected direct sensitivities are comparable to those obtained indirectly from electroweak precision observables. Two-dimensional fits further show that these processes retain quark-flavor information that can be poorly resolved by the renormalization-group-induced electroweak response. These results illustrate how flavor-resolved four-body Z processes can bridge the electroweak and flavor programs at FCC-ee, opening a new class of complementary precision observables.
ER -