在本研究中，我們利用大型強子對撞機（LHC）在√s=14TeV的對撞能量下，評估了類軸子粒子（ALP）的gaWW耦合靈敏度，其中亮度設定為L=300fb−1（當前運行）和L=3000fb−1（預期的未來高亮度）。通過在MadGraph5aMC@NLO上模擬pp→W±a(W±→l±νl),(a→γγ)過程，並使用了特定的參數集：fa=1TeV、CWW=2、CBB=1和Cg=gaf=0。為了更好區分信號和背景，我們對Ma>25GeV和Ma≤25GeV分別建立了選擇標準。結果表明，在1GeV<Ma<100GeV的ALP質量範圍內，我們將gaWW的靈敏度提高到了10−4GeV−1的水平，與現有限制相比，大約提高了一到兩個數量級。

In this study, we evaluated the sensitivity of the gaWW coupling for the axion-like particle (ALP) using the LHC at a center-of-mass energy of √s=14TeV, with luminosities set at L=300fb−1 (current operation) and L=3000fb−1 (anticipated future high luminosity). Simulating the process pp→W±a(W±→l±νl),(a→γγ) on the MadGraph5aMC@NLO, we utilized a specific parameter set: fa=1TeV, CWW=2, CBB=1 and Cg=gaf=0. To better differentiate between signal and background, we established selection criteria separately for Ma>25GeV and Ma≤25GeV. The results indicate that, in the ALP mass range 1GeV<Ma<100GeV, we improved the sensitivity of gaWW to the level of 10−4GeV−1, representing an enhancement of approximately one to two orders of magnitude compared to existing limits.

Contents
Contents ............................................. ii
List of Tables ....................................... iv
List of Figures ...................................... viii
1 Introduction ....................................... 1
2 The ALP Model ...................................... 3
3 Existing Constraints on ALPs ....................... 5
3.1 Supernova 1987A ............................... 5
3.2 Rare decays ................................... 6
3.3 Photon (various) .............................. 7
3.4 Nonresonant ggF (LHC) ......................... 7
3.5 Triboson ...................................... 8
4 Experiment and Simulation .......................... 10
4.1 Events Generation and Simulation .............. 10
4.2 Signal Events ................................. 11
4.3 Background Events ............................. 14
4.4 Selection Procedures .......................... 15
4.4.1 Ma > 25 GeV region ....................... 15
4.4.2 Ma ≤ 25 GeV region ....................... 18
5 Numerical Result ................................... 26
5.1 Significance Z ................................ 26
5.2 Calculation of Sensitivity Ranges ............. 27
5.3 Analysis of the gaWW constraint results ....... 27
6 Conclusion ......................................... 31
A Event Rates ........................................ 32
B The impact of choosing CWW and CBB on the results .. 35

[1] C. Abel et al. Measurement of the Permanent Electric Dipole Moment of the
Neutron. Phys. Rev. Lett., 124(8):081803, 2020.
[2] R. D. Peccei and Helen R. Quinn. CP Conservation in the Presence of In-
stantons. Phys. Rev. Lett., 38:1440–1443, 1977.
[3] I. Brivio, M. B. Gavela, L. Merlo, K. Mimasu, J. M. No, R. del Rey, and
V. Sanz. ALPs Effective Field Theory and Collider Signatures. Eur. Phys.
J. C, 77(8):572, 2017.
[4] Howard Georgi, David B. Kaplan, and Lisa Randall. Manifesting the Invisible
Axion at Low-energies. Phys. Lett. B, 169:73–78, 1986.
[5] Jie Ren, Daohan Wang, Lei Wu, Jin Min Yang, and Mengchao Zhang. Detect-
ing an axion-like particle with machine learning at the LHC. JHEP, 11:138,
2021.
[6] Kingman Cheung and C. J. Ouseph. Axionlike particle search at Higgs fac-
tories. Phys. Rev. D, 108(3):035003, 2023.
[7] Alexandre Payez, Carmelo Evoli, Tobias Fischer, Maurizio Giannotti,
Alessandro Mirizzi, and Andreas Ringwald. Revisiting the SN1987A gamma-
ray limit on ultralight axion-like particles. JCAP, 02:006, 2015.
[8] Eder Izaguirre, Tongyan Lin, and Brian Shuve. Searching for Axionlike
Particles in Flavor-Changing Neutral Current Processes. Phys. Rev. Lett.,
118(11):111802, 2017.
[9] G. Alonso-Álvarez, M. B. Gavela, and P. Quilez. Axion couplings to elec-
troweak gauge bosons. The European Physical Journal C, 79(3), March 2019.
[10] F Bergsma, Jheroen Dorenbosch, James V Allaby, Ugo Amaldi, Guido Barbi-
ellini, C Berger, Wilfried Flegel, L Lanceri, M Metcalf, C Nieuwenhuis, J Pan-
man, C Santoni, Klaus Winter, I Abt, J Aspiazu, F W Büsser, H Daumann,
P D Gall, T Hebbeker, F Niebergall, P Schütt, P Stähelin, P Gorbunov,
E A Grigoriev, V S Kaftanov, V D Khovanskii, A Rosanov, A Baroncelli,
L Barone, B Borgia, C Bosio, A Capone, M Diemoz, U Dore, F Ferroni,
E Longo, L Luminari, P Monacelli, F De Notaristefani, P Pistilli, R Santace-
saria, L Tortora, and V Valente. Search for axion-like particle production in
400 GeV proton-copper interactions. Phys. Lett. B, 157:458–462, 1985.
[11] Sonia Carra, Vincent Goumarre, Ruchi Gupta, Sarah Heim, Beate Heine-
mann, Jan Kuechler, Federico Meloni, Pablo Quilez, and Yee-Chinn Yap.
Constraining off-shell production of axionlike particles with Zγ and WW dif-
ferential cross-section measurements. Phys. Rev. D, 104(9):092005, 2021.
[12] Nathaniel Craig, Anson Hook, and Skyler Kasko. The photophobic alp. Jour-
nal of High Energy Physics, 2018(9), September 2018.
[13] Johan Alwall, Michel Herquet, Fabio Maltoni, Olivier Mattelaer, and Tim
Stelzer. MadGraph 5 : Going Beyond. JHEP, 06:128, 2011.
[14] Torbjorn Sjostrand, Stephen Mrenna, and Peter Z. Skands. A Brief Intro-
duction to PYTHIA 8.1. Comput. Phys. Commun., 178:852–867, 2008.
[15] J. de Favereau, C. Delaere, P. Demin, A. Giammanco, V. Lemaître,
A. Mertens, and M. Selvaggi. DELPHES 3, A modular framework for fast
simulation of a generic collider experiment. JHEP, 02:057, 2014.
[16] Matteo Cacciari, Gavin P. Salam, and Gregory Soyez. The anti-kt jet clus-
tering algorithm. JHEP, 04:063, 2008.
[17] Matteo Cacciari, Gavin P. Salam, and Gregory Soyez. FastJet User Manual.
Eur. Phys. J. C, 72:1896, 2012.
[18] Jesse Thaler and Ken Van Tilburg. Identifying Boosted Objects with N-
subjettiness. JHEP, 03:015, 2011.
[19] Study of the double Higgs production channel H(→ b ̄b)H(→ γγ) with the
ATLAS experiment at the HL-LHC. 1 2017.
[20] Glen Cowan, Kyle Cranmer, Eilam Gross, and Ofer Vitells. Asymptotic
formulae for likelihood-based tests of new physics. The European Physical
Journal C, 71(2), February 2011.