Probing axion-like particles coupling to gluons at the LHC

• Published in: The journal of high energy physics Vol. 2022; no. 7; pp. 70 - 23
• Main Authors: Ghebretinsae, Filmon Andom, Wang, Zeren Simon, Wang, Kechen
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2022; Springer Nature B.V; SpringerOpen
• Subjects: Axions and ALPs; Classical and Quantum Gravitation; Collaboration; Coupling; Elementary Particles; Gluons; High energy physics; Jets; Kinematics; Luminosity; Machine learning; Parameters; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Quarks; Regular Article - Theoretical Physics; Relativity Theory; Specific BSM Phenomenology; String Theory; Symmetry; Axions and ALPs; Specific BSM Phenomenology
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP07(2022)070

A bstract Assuming ALPs couple to gluons only, they can be produced via the pp → aj process and decay into two jets at the LHC. When the coupling parameter, C G ~ /f a , is small, the lifetime of ALPs can be long enough leading to displaced final state jets. In this paper, we consider the signal including both the prompt and long-lived cases of ALPs by employing a specialized Delphes module to handle displaced jets. Relevant background processes are generated and simulated at the detector level, and multivariate analyses based on machine-learning are performed to discriminate signal and background events and achieve the best sensitivities. Based on the data accumulated for this study, we forecast the expected upper limits on C G ~ /f a for ALP mass m a in the range 5–2300 GeV at 2-, 3- and 5- σ significances at the High Luminosity-LHC with 14 TeV center-of-mass energy and 3 ab −1 integrated luminosity. Vast previously unprobed regions in the parameter space spanned by C G ~ /f a and m a are probed and the best upper limits on C G ~ /f a at 2- σ significance are found to be around 1 . 0 × 10 −2 TeV −1 for m a ∼ 500 GeV. The ALP mass is reconstructed from the kinematics of final state jets and we find that it is measurable with this method when m a is below about 1 TeV at the HL-LHC. The effects of systematic uncertainties and validation of the EFT framework are also checked and discussed.