Search for resonances decaying into top-quark pairs using fully hadronic decays in pp collisions with ATLAS at sqrt(s) = 7 TeV

TL;DR

This paper reports a search for new heavy resonances decaying into top-quark pairs in fully hadronic final states at 7 TeV proton-proton collisions, using jet substructure techniques with the ATLAS detector, setting limits on Z' and Kaluza-Klein gluon masses.

Contribution

It introduces novel jet substructure methods to identify top-quark jets and sets new exclusion limits on specific resonance masses in fully hadronic decay channels.

Findings

No significant excess observed over Standard Model predictions.

Excluded Z' bosons with masses 0.70-1.00 TeV and 1.28-1.32 TeV.

Excluded Kaluza-Klein gluons with masses 0.70-1.62 TeV.

Abstract

A search for resonances produced in 7 TeV proton-proton collisions and decaying into top-quark pairs is described. In this Letter events where the top-quark decay produces two massive jets with large transverse momenta recorded with the ATLAS detector at the Large Hadron Collider are considered. Two techniques that rely on jet substructure are used to separate top-quark jets from those arising from light quarks and gluons. In addition, each massive jet is required to have evidence of an associated bottom-quark decay. The data are consistent with the Standard Model, and limits can be set on the production cross section times branching fraction of a Z' boson and a Kaluza-Klein gluon resonance. These limits exclude, at the 95% credibility level, Z' bosons with masses 0.70-1.00 TeV as well as 1.28-1.32 TeV and Kaluza-Klein gluons with masses 0.70-1.62 TeV.