Abstract
A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.
Highlights
The first paragraph on p. 15 of the original version should be replaced by the following paragraph, which deletes an incorrect reference to a figure
The uncertainties on the mistagged NTMJ background include the statistical uncertainty on the sample after loose selection, to which the mistag probability is applied; the statistical uncertainty on the mistag probability itself, ranging from
The total background uncertainty is ≈5% for the low-mass region, dominated by the systematic uncertainty, and ≈100% for the high-mass region, dominated by statistical uncertainty associated with the sample after loose selection
Summary
The first paragraph on p. 15 of the original version should be replaced by the following paragraph, which deletes an incorrect reference to a figure.
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