ALP-ine quests at the LHC: hunting axion-like particles via peaks and dips in $t \bar{t}$ production

Anuar, Afiq; Grohsjean, Alexander; Weiglein, Georg; Schwanenberger, Christian; Biekötter, Thomas; Jeppe, Laurids; Heinemeyer, Sven; Biekötter, Anke

Preprint

PUBDB-2024-01594

ALP-ine quests at the LHC: hunting axion-like particles via peaks and dips in $t \bar{t}$ production

Anuar, A.Extern*DESY* ; Biekötter, A. ; Biekötter, T.DESY* ; Grohsjean, A.Extern* ; Heinemeyer, S. ; Jeppe, L.DESY* ; Schwanenberger, C.DESY* ; Weiglein, G. (Corresponding author)DESY*

2024

[10.3204/PUBDB-2024-01594]

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Report No.: DESY-24-059; IFT-UAM/CSIC-24-042; KA-TP-06-2024; MITP-24-044; arXiv:2404.19014

Abstract: We present an analysis of the sensitivity of current and future LHC searches for new spin-0 particles in top-anti-top-quark ($t\bar{t}$) final states, focusing on generic axion-like particles (ALPs) that are coupled to top quarks and gluons. As a first step, we derive new limits on the effective ALP Lagrangian in terms of the Wilson coefficients $c_t$ and $c_{\tilde{G}}$ based on the results of the CMS search using $35.9$ fb$^{-1}$ of data, collected at $\sqrt{s} = 13$ TeV. We then investigate how the production of an ALP with generic couplings to gluons and top quarks can be distinguished from the production of a pseudoscalar which couples to gluons exclusively via a top-quark loop. To this end, we make use of the invariant $t\bar{t}$ mass distribution and angular correlations that are sensitive to the $t\bar{t}$ spin correlation. Using a mass of 400 GeV as an example, we find that already the data collected during Run 2 and Run 3 of the LHC provides an interesting sensitivity to the underlying nature of a possible new particle. We also analyze the prospects for data anticipated to be collected during the high-luminosity phase of the LHC. Finally, we compare the limits obtained from the $t \bar t$ searches to existing experimental bounds from LHC searches for narrow di-photon resonances, from measurements of the production of four top quarks, and from global analyses of ALP-SMEFT interference effects.

Keyword(s): top: pair production ; spin: correlation ; interference: effect ; interpretation of experiments: CERN LHC Coll ; gluon ; axion-like particles ; sensitivity ; two-photon ; interpretation of experiments: CMS ; angular correlation ; new particle ; pseudoscalar ; mass spectrum ; dip ; TeV