Prospects for observing the $\hat{I}{\cdot }_t$ $\to$ $W^{+}{W}^{-}$ decay at the HL-LHC

Abstract

Motivated by the recent observation of the pseudoscalar toponium $\hat{I}{\cdot }_t$ at the LHC and by the ongoing interest in its properties, we phenomenologically investigate the $\hat{I}{\cdot }_t$ $\to$ $W^{+}{W}^{-}$ process, one of the characteristic decays of toponium $\hat{I}{\cdot }_t$. The branching ratio for the $\hat{I}{\cdot }_t$ $\to$ $W^{+}{W}^{-}$ decay is estimated with two scenarios of the decay constant $f_{\hat{I}{\cdot }_t}$. It is found that tens of dilepton events from the cascade decays, $\hat{I}{\cdot }_t$ $\to$ $W^{+}{W}^{-}$ $\to$ ${\ell }^{-}\bar{\hat{I}}{½}_{\ell }{\ell }^{\prime +}\hat{I}{½}_{{\ell }^{\prime }}$ with $\ell$, ${\ell }^{\prime }$ $=$ $e$ and $\hat{I}¼$, could be experimentally observed, when considering the realistic identification efficiency of the charged lepton and assuming more than $3\times 10^7$ $\hat{I}{\cdot }_t$ events available at the future HL-LHC. We propose searching for $\hat{I}{\cdot }_t$ via the $\hat{I}{\cdot }_t$ $\to$ $W^{+}{W}^{-}$ $\to$ ${\ell }^{-}\bar{\hat{I}}{½}_{\ell }{\ell }^{\prime +}\hat{I}{½}_{{\ell }^{\prime }}$ channel, which features no $b$-jets and clean dilepton signatures, thus offering a complementary and potentially more sensitive probe.

20 pages