Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector

G. Aad; B. Abbott; J. Abdallah; O. Abdinov; R. Aben; M. Abolins; O.S. AbouZeid; H. Abramowicz; H. Abreu; R. Abreu; Mogens Dam; Jørn Dines Hansen; Jørgen Beck Hansen; Stefania Xella; Peter Henrik Hansen; Troels Christian Petersen; Lotte Ansgaard Thomsen; Sascha Mehlhase; Morten Dam Jørgensen; Almut Maria Pingel; Ask Emil Løvschall-Jensen; Alejandro Alonso Diaz; James William Monk; Lars Egholm Pedersen; Graig Wiglesworth; Gorm Aske Gram Krohn Galster

doi:10.1007/jhep08(2015)105

Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector

G. Aad, B. Abbott, J. Abdallah, O. Abdinov, R. Aben, M. Abolins, O.S. AbouZeid, H. Abramowicz, H. Abreu, R. Abreu, Mogens Dam, Jørn Dines Hansen, Jørgen Beck Hansen, Stefania Xella, Peter Henrik Hansen, Troels Christian Petersen, Lotte Ansgaard Thomsen, Sascha Mehlhase, Morten Dam Jørgensen, Almut Maria PingelAsk Emil Løvschall-Jensen, Alejandro Alonso Diaz, James William Monk, Lars Egholm Pedersen, Graig Wiglesworth, Gorm Aske Gram Krohn Galster

Experimental Particle Physics

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Abstract

A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at (Formula presented.) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb⁻¹. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT¯→Wb+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT¯→Ht+XandBB¯→Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.

Original language	English
Article number	105
Journal	Journal of High Energy Physics (Online)
Volume	2015
Issue number	8
ISSN	1126-6708
DOIs	https://doi.org/10.1007/jhep08(2015)105
Publication status	Published - 31 Aug 2015

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Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Aben, R., Abolins, M., AbouZeid, O. S., Abramowicz, H., Abreu, H., Abreu, R., Dam, M., Hansen, J. D., Hansen, J. B., Xella, S., Hansen, P. H., Petersen, T. C., Thomsen, L. A., Mehlhase, S., Jørgensen, M. D., ... Galster, G. A. G. K. (2015). Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector. Journal of High Energy Physics (Online), 2015(8), [105]. https://doi.org/10.1007/jhep08(2015)105

Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector. / Aad, G.; Abbott, B.; Abdallah, J. et al.

In: Journal of High Energy Physics (Online), Vol. 2015, No. 8, 105, 31.08.2015.

Research output: Contribution to journal › Journal article › Research › peer-review

Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Dam, M , Hansen, JD , Hansen, JB , Xella, S , Hansen, PH , Petersen, TC, Thomsen, LA, Mehlhase, S, Jørgensen, MD, Pingel, AM, Løvschall-Jensen, AE, Alonso Diaz, A, Monk, JW, Pedersen, LE, Wiglesworth, G & Galster, GAGK 2015, 'Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector', Journal of High Energy Physics (Online), vol. 2015, no. 8, 105. https://doi.org/10.1007/jhep08(2015)105

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title = "Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector",

abstract = "A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at (Formula presented.) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT¯→Wb+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT¯→Ht+XandBB¯→Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.",

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AU - Abbott, B.

AU - Abdallah, J.

AU - Abdinov, O.

AU - Aben, R.

AU - Abolins, M.

AU - AbouZeid, O.S.

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abreu, R.

AU - Dam, Mogens

AU - Hansen, Jørn Dines

AU - Hansen, Jørgen Beck

AU - Xella, Stefania

AU - Hansen, Peter Henrik

AU - Petersen, Troels Christian

AU - Thomsen, Lotte Ansgaard

AU - Mehlhase, Sascha

AU - Jørgensen, Morten Dam

AU - Pingel, Almut Maria

AU - Løvschall-Jensen, Ask Emil

AU - Alonso Diaz, Alejandro

AU - Monk, James William

AU - Pedersen, Lars Egholm

AU - Wiglesworth, Graig

AU - Galster, Gorm Aske Gram Krohn

PY - 2015/8/31

Y1 - 2015/8/31

N2 - A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at (Formula presented.) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT¯→Wb+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT¯→Ht+XandBB¯→Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.

AB - A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at (Formula presented.) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT¯→Wb+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT¯→Ht+XandBB¯→Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.

U2 - 10.1007/jhep08(2015)105

DO - 10.1007/jhep08(2015)105

M3 - Journal article

SN - 1126-6708

VL - 2015

JO - Journal of High Energy Physics (Online)

JF - Journal of High Energy Physics (Online)

IS - 8

M1 - 105

ER -

Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at root 8=8 TeV with the ATLAS detector

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