Search for Single Production of a Vector-like Quark Via a Heavy Gluon in the 4b Final State with the ATLAS Detector in Pp Collisions at

Search for Single Production of a Vector-like Quark Via a Heavy Gluon in the 4b Final State with the ATLAS Detector in Pp Collisions at
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Total Pages: 20
Release: 2016
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In this study, a search is performed for the process pp → G* → BH$ar{b}$/$ar{B}$Hb → H$bar{b}$→ $bar{b}bar{b}$, predicted in composite Higgs scenarios, where G* is a heavy colour octet vector resonance and BHBH a vector-like quark of charge –1/3. The data were obtained from pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.5 fb–1, recorded by the ATLAS detector at the LHC. The largest background, multijet production, is estimated using a data-driven method. No significant excess of events with respect to Standard Model predictions is observed, and upper limits on the production cross section times branching ratio are set. Comparisons to the predictions from a specific benchmark model are made, resulting in lower mass limits in the two-dimensional mass plane of mG* vs. mBH.

Search for Single Production of a Vector-like Quark Via a Heavy Gluon in the 4b Final State with the ATLAS Detector in Pp Collisions at [mml

Search for Single Production of a Vector-like Quark Via a Heavy Gluon in the 4b Final State with the ATLAS Detector in Pp Collisions at [mml
Author:
Publisher:
Total Pages: 20
Release: 2016
Genre:
ISBN:
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Download Search for Single Production of a Vector-like Quark Via a Heavy Gluon in the 4b Final State with the ATLAS Detector in Pp Collisions at [mml Book in PDF, Epub and Kindle

In this study, a search is performed for the process pp → G* → BH$\bar{b}$/$\bar{B}$Hb → H$b\bar{b}$→ $b\bar{b}b\bar{b}$, predicted in composite Higgs scenarios, where G* is a heavy colour octet vector resonance and BHBH a vector-like quark of charge -1/3. The data were obtained from pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.5 fb-1, recorded by the ATLAS detector at the LHC. The largest background, multijet production, is estimated using a data-driven method. No significant excess of events with respect to Standard Model predictions is observed, and upper limits on the production cross section times branching ratio are set. Comparisons to the predictions from a specific benchmark model are made, resulting in lower mass limits in the two-dimensional mass plane of mG* vs. mBH.

Search for Pair-produced Vector-like B Quarks in Proton-proton Collisions at $\sqrt{s}$

Search for Pair-produced Vector-like B Quarks in Proton-proton Collisions at $\sqrt{s}$
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Total Pages: 46
Release: 2015
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A search for the production of a heavy B quark, having electric charge -1/3 and vector couplings to W, Z, and H bosons, is carried out using proton-proton collision data recorded at the CERN LHC by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb-1 . The B quark is assumed to be pair-produced and to decay in one of three ways: to tW, bZ, or bH. The search is carried out in final states with one, two, and more than two charged leptons, as well as in fully hadronic final states. Each of the channels in the exclusive final-state topologies is designed to be sensitive to specific combinations of the B quark-antiquark pair decays. The observed event yields are found to be consistent with the standard model expectations in all the fi- nal states studied. Our statistical combination of these results was performed and upper limits were set on the cross section of the strongly produced B quark-antiquark pairs as a function of the B quark mass. Additionally, lower limits on the B quark mass between 740 and 900 GeV are set at a 95% confidence level, depending on the values of the branching fractions of the B quark to tW, bZ, and bH. Overall, these limits are the most stringent to date.

Search for a Heavy Bottom-like Quark in Pp Collisions at Sqrt(s)

Search for a Heavy Bottom-like Quark in Pp Collisions at Sqrt(s)
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Release: 2011
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A search for pair-produced bottom-like quarks in pp collisions at sqrt(s) = 7 TeV is conducted with the CMS experiment at the LHC. The decay b' to tW is considered in this search. The b' b'-bar to tW-̂ t-bar W+̂ process can be identified by the distinctive signature of trileptons and same-sign dileptons. With a data sample corresponding to an integrated luminosity of 34 inverse picobarns, no excess above the standard model background predictions is observed and a b' quark with a mass between 255 and 361 GeV/c2̂ is excluded at the 95% confidence level.