2025/05/27 by Chenarani, Shirin, Najafabadi, Mojtaba Mohammadi · 1 citation
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2505.21305
Axion-like particles (ALPs) are pseudo Nambu-Goldstone bosons associated with spontaneously broken global symmetries incorporated in the Standard Model (SM) Lagrangian in many models beyond the SM. The existence of a light ALP is plausible due to the long-standing problems that the SM has not been able to address, such as the dark matter (DM) problem and the observed matter-antimatter asymmetry. There are many proposals in recent decades considering the ALP as a solution to some of these shortcomings. Motivated by such potential, we search for ALPs with a mass of 1 MeV at the LHC in a model-independent fashion. We explore two complementary production modes: ALP production in association with a pair of electroweak gauge bosons (ZZ or WW) and ALP production in association with a single gauge boson (W or Z) plus jets. For the VV+a final state, signal and dominant SM backgrounds are generated, and a realistic detector response simulation is performed. A multivariate analysis is employed to discriminate the VV+a signal from background processes, and the expected 95% confidence level (CL) exclusion limits in two-dimensional parameter spaces involving the ALP couplings are subsequently derived. The V+jets channel is interpreted using LHC measurements in regimes where the ALP escapes detection, appearing as missing energy. The two analyses are complementary: both the VV+a and the V+jets channels probe simultaneously the ALP couplings to gluons and to electroweak gauge bosons. While the VV+a channel offers clean multi-lepton final states and direct reconstruction of the ZZ or WW system, the V+jets channel benefits from larger production cross sections, enabling stronger constraints in certain regions of the parameter space.