Search for single b*-quark production with the ATLAS detector at sqrt(s)=7 TeV

TL;DR

This paper reports a search for excited bottom-quarks (b*) in proton-proton collisions at 7 TeV using ATLAS data, setting mass exclusion limits up to 870 GeV based on decay signatures involving W bosons and top quarks.

Contribution

First search for single b*-quark production at 7 TeV with ATLAS, establishing mass exclusion limits and constraining b*-quark couplings.

Findings

Excluded b*-quark masses below 870 GeV at 95% credibility.

Set limits on b*-quark couplings for various masses.

Combined dilepton and lepton+jets channels for improved sensitivity.

Abstract

The results of a search for an excited bottom-quark b* in pp collisions at sqrt(s)=7 TeV, using 4.7/fb of data collected by the ATLAS detector at the LHC are presented. In the model studied, a single b*-quark is produced through a chromomagnetic interaction and subsequently decays to a W boson and a top-quark. The search is performed in the dilepton and lepton+jets final states, which are combined to set limits on b*-quark couplings for a range of b*-quark masses. For a benchmark with unit size chromomagnetic and Standard Model-like electroweak b* couplings, b*-quarks with masses less than 870 GeV are excluded at the 95% credibility level.