Search for the ${\hat{I}}^{3}Z$ decay mode of heavy photophobic axion-like particles at the LHC

Abstract

We assume the coupling of Axion-like particle (ALP) to diphoton $g_{a{\hat{I}}^3{\hat{I}}^3}\sim 0$ and accomplish detailed analyses for the ${\hat{I}}^{3}Z$ decay mode of such heavy photophobic ALPs at the high luminosity-Large Hadron Collider (HL-LHC). ALPs are produced with two jets via both the $s$-channel vector boson exchange and vector boson fusion processes, with the signal process $pp\to jja(\to {\hat{I}}^{3}Z(\to {\ell }^{+}{\ell }^{-}))$ for $\ell =e,\hat{I}¼$. Signal and background events are simulated at the detector-level. Preselection criteria target events with one photon, two oppositely charged electrons or muons, and two non-$b$-tagged jets. The ALP mass is reconstructed, and kinematic observables are input into a machine learning-based multivariate analysis for optimal background rejection. Discover sensitivities on the ALP's coupling to di-$W$ boson, $g_{aWW}$, are presented in the mass range from 100 to 4000 GeV at center-of-mass energy $\sqrt{s}=14$ TeV and integrated luminosity $\mathcal{L}=$ 3 ab${}^{-1}$ and 140 fb${}^{-1}$. Sensitivities on the production cross section $\ddot{I}ƒ(pp\to jja)$ times the branching ratio Br$(a\to {\hat{I}}^{3}Z)$ are also presented.

24 pages, 10 figures, 3 tables; details are added; typos are fixed