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Main Authors: Wang, Shi-Yu, Jiao, Yu-Peng, Zhang, Hong-Hao, Cacciapaglia, Giacomo
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.17718
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author Wang, Shi-Yu
Jiao, Yu-Peng
Zhang, Hong-Hao
Cacciapaglia, Giacomo
author_facet Wang, Shi-Yu
Jiao, Yu-Peng
Zhang, Hong-Hao
Cacciapaglia, Giacomo
contents We investigate the potential to probe axion-like particles (ALPs) under the photophobic scenario at the FCC-ee and CEPC at the Z-pole, with $\sqrt{s} = 91.2$ GeV. The signal process is $$ e^+e^- \to Z \to γa,\quad a \to \ell^+ \ell^-, $$ where we consider final states with two prompt leptons and one photon, or only one photon (Mono-$γ$). We estimate the sensitivity to the ALP mass $m_a$ and associated energy scale $Λ$ for $a\toμ^+μ^-$ and $a\toτ^+τ^-$ (with leptonic decays of the $τ$) by use of a XGBoost classifier. For an integrated luminosity of 150 ab$^{-1}$ at the Z-pole, the combined leptonic channel can probe the ALP scale $Λ$ between $10$ to $700$~TeV, depending on the ALP mass. The Mono-$γ$ signal offers a complementary probe, reaching $Λ$ up to $2000$~TeV for masses below $20$~GeV.
format Preprint
id arxiv_https___arxiv_org_abs_2509_17718
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Probing Long-Lived Photophobic Axion-Like Particles via Prompt Leptons and Mono-$γ$ at FCC-ee and CEPC
Wang, Shi-Yu
Jiao, Yu-Peng
Zhang, Hong-Hao
Cacciapaglia, Giacomo
High Energy Physics - Phenomenology
We investigate the potential to probe axion-like particles (ALPs) under the photophobic scenario at the FCC-ee and CEPC at the Z-pole, with $\sqrt{s} = 91.2$ GeV. The signal process is $$ e^+e^- \to Z \to γa,\quad a \to \ell^+ \ell^-, $$ where we consider final states with two prompt leptons and one photon, or only one photon (Mono-$γ$). We estimate the sensitivity to the ALP mass $m_a$ and associated energy scale $Λ$ for $a\toμ^+μ^-$ and $a\toτ^+τ^-$ (with leptonic decays of the $τ$) by use of a XGBoost classifier. For an integrated luminosity of 150 ab$^{-1}$ at the Z-pole, the combined leptonic channel can probe the ALP scale $Λ$ between $10$ to $700$~TeV, depending on the ALP mass. The Mono-$γ$ signal offers a complementary probe, reaching $Λ$ up to $2000$~TeV for masses below $20$~GeV.
title Probing Long-Lived Photophobic Axion-Like Particles via Prompt Leptons and Mono-$γ$ at FCC-ee and CEPC
topic High Energy Physics - Phenomenology
url https://arxiv.org/abs/2509.17718