Axion-Like Particle Searches at Muon Colliders: Photon-Neutrino Signatures and Heavy-Neutral-Lepton Feasibility
Abstract
We study the mono-photon signature μ+μ-→γa→γνν̅ at $3$ and 10TeV muon colliders, with integrated luminosities of $1$ and 10 ab−1, in a two-coupling axion-like-particle (ALP) simplified model. Five benchmarks spanning ma=100--1000GeV are generated at gaγγ=0.01TeV−1 and flavor-universal pseudoscalar neutrino couplings yν=0.1 or $0.3$, giving invisible branching fractions above 99.995\% and mono-photon cross sections of $0.00854−−0.01217\,\mathrm{fb}$. Assuming a 1\% background normalization uncertainty, a cut-based photon-line selection gives projected 95\% sensitivity to gaγγ≃0.039--0.045TeV−1 at 3TeV and $0.0137−−0.0140\TeV^{-1}$ at 10TeV. A ROOT/TMVA gradient-boosted decision tree with validation-fixed thresholds reaches held-out AUC values of $0.9967−−0.9993$ and g95=0.0192--0.0400TeV−1 at 3TeV and $0.0122−−0.0144\TeV^{-1}$ at 10TeV. Because only 2-41 irreducible-background test events populate the optimized classifier tails, the mass--coupling contours are reported as projected expected sensitivities rather than profile-likelihood or CLs exclusions. A separate appendix records a phenomenological, parton-level HNL diphoton feasibility study; it is not used to claim detector-level sensitivity or exclusion.} \keywords{Axion-like particles, muon collider, mono-photon, diphoton, heavy neutral leptons, neutrinos, multivariate analysis, effective field theory
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BibTeX
@misc{ahmed2026axionlike,
title = {{Axion-Like Particle Searches at Muon Colliders: Photon-Neutrino Signatures and Heavy-Neutral-Lepton Feasibility}},
author = {Ijaz Ahmed and Waqas Ahmad and M. Tayyab Javaid and Jamil Muhammad},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27006},
eprint = {2610.27006},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27006},
}
RIS
TY - UNPB
TI - Axion-Like Particle Searches at Muon Colliders: Photon-Neutrino Signatures and Heavy-Neutral-Lepton Feasibility
AU - Ijaz Ahmed
AU - Waqas Ahmad
AU - M. Tayyab Javaid
AU - Jamil Muhammad
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.27006
UR - https://arxiv.org/abs/2610.27006
AB - We study the mono-photon signature μ^+μ^-→γa→γνν̅ at $3$ and 10TeV muon colliders, with integrated luminosities of $1$ and 10 ab^−1, in a two-coupling axion-like-particle (ALP) simplified model. Five benchmarks spanning m_a=100--1000GeV are generated at g_aγγ=0.01TeV^−1 and flavor-universal pseudoscalar neutrino couplings y_ν=0.1 or $0.3$, giving invisible branching fractions above 99.995\% and mono-photon cross sections of $0.00854−−0.01217\,\mathrm{fb}$. Assuming a 1\% background normalization uncertainty, a cut-based photon-line selection gives projected 95\% sensitivity to g_aγγ≃0.039--0.045TeV^−1 at 3TeV and $0.0137−−0.0140\TeV^{-1}$ at 10TeV. A ROOT/TMVA gradient-boosted decision tree with validation-fixed thresholds reaches held-out AUC values of $0.9967−−0.9993$ and g_95=0.0192--0.0400TeV^−1 at 3TeV and $0.0122−−0.0144\TeV^{-1}$ at 10TeV. Because only 2-41 irreducible-background test events populate the optimized classifier tails, the mass--coupling contours are reported as projected expected sensitivities rather than profile-likelihood or CL_s exclusions. A separate appendix records a phenomenological, parton-level HNL diphoton feasibility study; it is not used to claim detector-level sensitivity or exclusion.} \keywords{Axion-like particles, muon collider, mono-photon, diphoton, heavy neutral leptons, neutrinos, multivariate analysis, effective field theory
ER -