Probing axion-like particles coupling to gluons at the LHC

Abstract

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 machinelearning 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 is 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 in 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.

Probing HNL‐ALP Couplings at Colliders

“…On the experimental side, the efforts pointed towards the construction of a consistent effective description of ALPs, [25][26][27][28][29][30][31][32] beyond the seminal study in Ref. [33], in order to investigate DOI: 10.1002/prop.202300027 possible signals at low-energy facilities, [34][35][36][37][38][39][40][41][42][43][44] colliders [25,[45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] and in non-terrestrial environments. [62][63][64][65] Most of the analyses performed on collider data and from astrophysics deal with an on-shell ALP in the initial or final state of the considered processes, such as mono-Z, mono-W, and mono-Higgs searches or stellar cooling, and the associated bounds strongly depend on the ALP mass.…”