Paper of the Week


Search for top-squark pairs decaying into Higgs or Z bosons in pp collisions at sqrt(s) = 8 TeV

Physics Letters B, 736, 371 (2014)

P. Baringer*, A. Bean*, G. Benelli*, C. Bruner*, J. Gray*, R.P. Kenny* III, M. Murray*, D. Noonan*, S. Sanders*, J. Sekaric*, R. Stringer*, Q. Wang*, J.S. Wood*, and the CMS Collaboration
* KU Physics and Astronomy Authors

ABSTRACT

A search for supersymmetry through the direct pair production of top squarks, with Higgs (H) or Z bosons in the decay chain, is performed using a data sample of proton-proton collisions at sqrt{s}=8 TeV collected in 2012 with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 19.5 fb^-1. The search is performed using a selection of events containing leptons and bottom-quark jets. No evidence for a significant excess of events over the standard model background prediction is observed. The results are interpreted in the context of simplified supersymmetric models with pair production of a heavier top-squark mass eigenstate t˜2 decaying to a lighter top-squark mass eigenstate t˜1 via either t˜2-->Ht˜1 or t˜2-->Zt˜1, followed in both cases by t˜1-->tchi˜10, where chi˜10 is an undetected, stable, lightest supersymmetric particle. The interpretation is performed in the region where the mass difference between the t˜1 and chi˜10 states is approximately equal to the top-quark mass t˜1-mchi˜10~=mt), which is not probed by searches for direct t˜1 squark pair production. The analysis excludes top squarks with masses m_t˜2 < 575 GeV and m_t˜1 < 400 GeV at a 95% confidence level.

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