Abstract
Axion-like particles (ALPs) are pseudo Nambu-Goldstone bosons associated with spontaneously broken global symmetries emerging in many extensions of the Standard Model. Assuming the most general effective Lagrangian up to dimension-5 operators for an ALP interacting with the SM fields, we investigate for the first time the sensitivity of the LHC13 to the ALP production in association with a di-jet. This study is focused on light ALPs which appear as invisible particles at the detector. Performing a realistic detector simulation and deploying a multivariate technique to best discriminate the signal from backgrounds, we set expected upper bounds on the ALP coupling to gluons. A comprehensive set of background processes is considered, and it is shown that this process provides significant sensitivity to the ALP-gluon coupling and the resulting bound is more stringent than those already obtained at the LHC. We also present prospects for the HE-LHC27 and FCC-hh100 and show that these future colliders are able to improve the limits from the LHC by roughly one order of magnitude.
Highlights
The Standard Model (SM) of particle physics provides remarkable predictions which have been successfully verified in plenty of experimental observations
Motivated by the possibilities such particles provide to address some of the SM problems, e.g., the dark matter problem, strong CP problem, baryon asymmetry problem, neutrino mass problem, etc., we examine the potential of the production process pp → a þ jj to search for light axionlike particles (ALPs) and to probe the parameter space of the model at the present and future proton-proton colliders
We present expected 95% C.L. upper limits on the ALP coupling to gluons at the LHC (13 TeV), High-Energy Large Hadron Collider (HE-LHC) (27 TeV), and Future Circular Collider (FCC)-hh (100 TeV)
Summary
The Standard Model (SM) of particle physics provides remarkable predictions which have been successfully verified in plenty of experimental observations. Searches for the exotic Higgs decays h → aZ and h → aa with subsequent ALP decays a → γγ and a → lþl− at the LHC have been performed providing significant sensitivities in large regions of unprobed parameter space [32,33,34,35] These channels display reasonable sensitivity to the ALP couplings to photons and leptons for ALP masses above a few MeV. The discriminating variables are carefully chosen so that the best discrimination is obtained Utilizing this signal process, we set expected upper limits on the ALP-gluon coupling at the LHC (13 TeV) for light ALPs with masses ma 1⁄4 0.1, 0.4, 0.7, and 1 MeV. IV, we present collider searches for the ALP production in association with two jets and set upper bounds on the ALP coupling to gluons
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