Search for heavy scalar or pseudoscalar states in $\mathrm{t \bar{t}}$ events at CMS

A search for scalar or pseudoscalar states decaying to a top quark-antiquark pair ( \mathrm{t \bar{t}} t t ‾ ), using 138 \mathrm{ fb}^{-1} 138 f b − 1 of pp collision data taken at \sqrt{s} = 13 \mathrm{ TeV} s = 13 T e V using the CMS detector, is presented. Events with one or two leptons are analyzed using the invariant \mathrm{t \bar{t}} t t ‾ mass ( m_{\mathrm{t \bar{t}}} m t t ‾ ) as well as angular and spin correlation observables. An excess in the data is observed for low values of m_{\mathrm{t \bar{t}}} m t t ‾ , preferring a pseudoscalar over a scalar hypothesis. It is interpreted in terms of a generic model of (pseudo)scalar boson production, as well as a simplified model of a \mathrm{t \bar{t}} t t ‾ bound state ( \eta_{\mathrm{t}} η t ), yielding good agreement with the data. Moreover, limits on the couplings of additional (pseudo)scalar bosons to top quarks are set.