Shedding light on top partner at the LHC
2019; Springer Nature; Volume: 2019; Issue: 1 Linguagem: Inglês
10.1007/jhep01(2019)139
ISSN1127-2236
AutoresHaider Alhazmi, Jeong Han Kim, Kyoungchul Kong, Ian Lewis,
Tópico(s)High-Energy Particle Collisions Research
ResumoA bstract 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 → t γ 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- $$ \frac{1}{2} $$ 1 2 and spin- $$ \frac{3}{2} $$ 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 → t γ) ≪ 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 $$ T\overline{T}\to t\overline{t}\gamma g $$ T T ¯ → t t ¯ γ g is more significant than the sensitivity to $$ T\overline{T}\to t\overline{t} gg $$ T T ¯ → t t ¯ gg . This is due to much smaller backgrounds attributed to the isolated high- p T photon. We find that with these decay channels and 3 ab −1 of data, the LHC is sensitive to top partner masses m T ≲ 1 . 4-1 . 8 TeV for spin- $$ \frac{1}{2} $$ 1 2 and spin- $$ \frac{3}{2} $$ 3 2 top partners, respectively.
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