Abstract
We investigate the sensitivity of the 14 TeV LHC to pair-produced top partners (T) decaying into the Standard Model top quark (t) plus either a gluon (g) or a photon (γ). The decays T → tg and T → tγ can be dominant when the mixing between the top partner and top quark are negligible. In this case, the conventional decays T → bW , T → tZ, and T → th are highly suppressed and can be neglected. We take a model-independent approach using effective operators for the T -t-g and T -t-γ interactions, considering both spin- \( \frac{1}{2} \) and spin- \( \frac{3}{2} \) top partners. We perform a semi-realistic simulation with boosted top quark tagging and an appropriate implementation of a jet-faking-photon rate. Despite a simple dimensional analysis indicating that the branching ratios BR(T → tγ) ≪ BR(T → tg) due to the electric-magnetic coupling being much smaller than the strong force coupling, our study shows that the LHC sensitivity to \( T\overline{T}\to t\overline{t}\gamma g \) is more significant than the sensitivity to \( T\overline{T}\to t\overline{t} gg \). This is due to much smaller backgrounds attributed to the isolated high-pT photon. We find that with these decay channels and 3 ab−1 of data, the LHC is sensitive to top partner masses mT ≲ 1.4-1.8 TeV for spin- \( \frac{1}{2} \) and spin- \( \frac{3}{2} \) top partners, respectively.
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Alhazmi, H., Kim, J.H., Kong, K. et al. Shedding light on top partner at the LHC. J. High Energ. Phys. 2019, 139 (2019). https://doi.org/10.1007/JHEP01(2019)139
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DOI: https://doi.org/10.1007/JHEP01(2019)139