Journal article

Search for same-sign top-quark production and fourth-generation down-type quarks in pp collisions at root s=7 TeV with the ATLAS detector

G Aad, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, A Abdesselam, O Abdinov, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, E Acerbi, BS Aeharya, L Adamezyk, DL Aams, TN Addy, J Adelman, M Aderhoz, S Adomeit Show all

JOURNAL OF HIGH ENERGY PHYSICS | SPRINGER | Published : 2012

Abstract

A search is presented for same-sign top-quark production and down-type heavy quarks of charge -1/3 in events with two isolated leptons (e or μ) that have the same electric charge, at least two jets and large missing transverse momentum. The data are selected from pp collisions at ps = 7 TeV recorded by the ATLAS detector and correspond to an integrated luminosity of 1.04 fb-1. The observed data are consistent with expectations from Standard Model processes. Upper limits are set at 95% confidence level on the cross section of new sources of same-sign top-quark pair production of 1.4-2.0 pb depending on the assumed mediator mass. Upper limits are also set on the pair-production cross-section f..

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Grants

Awarded by Science and Technology Facilities Council


Funding Acknowledgements

We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN: CONICYT, Chile: CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF, DNSRC and Lundbeck Foundation, Denmark; EPLANET and ERC, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNAS, Georgia; BMBF, DFG, HGF, MPG and AvH Foundation, Germany: GSRT, Greece; ISF, MINERVA, CIF, Center, Israel; INFN, Italy; MEXT and,JSPS Japan; CNRST, MoroccDIP and Benoziyoo; FOM and NAWO, Netherlands; RCN, Norway; MNiSW, Poland; GRICES and FCT, Portugal; MERYS (MECTS), Romania; MES of Russia and ROSATOM, Russian Federation; JINR; MSTD Serbia; MSSR, Slovakia; ARRS and MVZT, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SER, SNSF and Cantons of Bern and Geneva, Switzerland; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States of America. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN and the ATLAS Tier-1 facilities at TRIUMF (Canada), NOGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NI.-T1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (U.K.) and anBNL (U.S.A.) d in the Tier-2 facilities worldwide.