Search For Direct Pair Production Research Articles

Search for a heavy top-quark partner in final states with two leptons with the ATLAS detector at the LHC

Abstract The results of a search for direct pair production of heavy top-quark partners in 4.7 fb−1 of integrated luminosity from pp collisions at $ \sqrt{s}=7 $ TeV collected by the ATLAS detector at the LHC are reported. Heavy top-quark partners decaying into a top quark and a neutral non-interacting particle are searched for in events with two leptons in the final state. No excess above the Standard Model expectation is observed. Limits are placed on the mass of a supersymmetric scalar top and of a spin-1/2 top-quark partner. A spin-1/2 top-quark partner with a mass between 300 GeV and 480 GeV, decaying to a top quark and a neutral non-interacting particle lighter than 100 GeV, is excluded at 95% confidence level.

Search for Pair Production of Light Scalar Top Quarks inpp¯Collisions ats=1.8 TeV

Using 85.2±3.6 pb−1 of pp¯ collisions collected at s=1.8 TeV with the D0 detector at Fermilab’s Tevatron Collider, we present the results of a search for direct pair production of scalar top quarks (t˜), the supersymmetric partners of the top quark. We examined events containing two or more jets and missing transverse energy, the signature of light scalar top quark decays to charm quarks and neutralinos. After selections, we observe 27 events while expecting 31.1±6.4 events from known standard model processes. Comparing these results to next-to-leading-order production cross sections, we exclude a significant region of t˜ and neutralino phase space. In particular, we exclude the t˜ mass mt˜<122 GeV/c2 for a neutralino mass of 45 GeV/c2.Received 9 February 2004DOI:https://doi.org/10.1103/PhysRevLett.93.011801©2004 American Physical Society