ttbar+Large missing energy from top-quark partners: a comprehensive study at NLO QCD

Understand

We perform a detailed study of top-quark partner production in the ttbar plus large missing energy final-state at the LHC, presenting results for both scalar and fermionic top-quark partners in the semi-leptonic and dileptonic decay modes of the top quarks.

• We compare the results of several simulation tools: leading-order matrix elements, next-to-leading order matrix elements, leading-order plus parton shower simulations, and merged samples that contain the signal process with an additional hard jet radiated.
• We find that predictions from leading-order plus parton shower simulations can significantly deviate from NLO QCD or LO merged samples and do not correctly model the kinematics of the ttbar + ETmiss signature.
• They are therefore not a good framework for modeling this new physics signature.