Impact of Rare Decays $t\to {\ell }^{\prime }\nu b\ell \ell$ and $t\to q{q}^{\prime }b\ell \ell$ on Searches for Top-Associated Physics

Abstract

Searches for top quark-associated physics such as $t\bar{t}W$ or $t\bar{t}H$ in final states with multiple leptons require a careful accounting of expected backgrounds due to the lack of reconstructible resonances. We demonstrate that the rare top quark decays $t\to {\ell }^{\prime }\nu b\ell \ell$ and $t\to q{q}^{\prime }b\ell \ell$, when a soft lepton is not detected, can contribute a non-negligible background to such searches. Simulations in the LHC experiments typically do not account for such decays and as such backgrounds to such searches may be underestimated.

13 pages, 6 figures

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• Search for squarks and gluinos in final states with same-sign leptons and jets using 139 fb${}^{-1}$ of data collected with the ATLAS detector