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Search for new phenomena in tt events with large missing transverse momentum in proton-proton collisions at sqrt[s] = 7 TeV with the ATLAS detector |
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| Authors: | Aad G Abbott B Abdallah J Abdelalim A A Abdesselam A Abdinov O Abi B Abolins M Abramowicz H Abreu H Acerbi E Acharya B S Adams D L Addy T N Adelman J Aderholz M Adomeit S Adragna P Adye T Aefsky S Aguilar-Saavedra J A Aharrouche M Ahlen S P Ahles F Ahmad A Ahsan M Aielli G Akdogan T Akesson T P A Akimoto G Akimov A V Akiyama A Alam M S Alam M A Albert J Albrand S Aleksa M Aleksandrov I N Alessandria F Alexa C Alexander G Alexandre G Alexopoulos T Alhroob M Aliev M Alimonti G Alison J Aliyev M Allport P P Allwood-Spiers S E Almond J Aloisio A Alon R Alonso A Alviggi M G Amako K Amaral P |
| Institution: | Fakult?t für Mathematik und Physik, Albert-Ludwigs-Universit?t, Freiburg i.Br., Germany. |
| Abstract: | A search for new phenomena in tt events with large missing transverse momentum in proton-proton collisions at a center-of-mass energy of 7 TeV is presented. The measurement is based on 1.04 fb(-1) of data collected with the ATLAS detector at the LHC. Contributions to this final state may arise from a number of standard model extensions. The results are interpreted in terms of a model where new top-quark partners are pair produced and each decay to an on-shell top (or antitop) quark and a long-lived undetected neutral particle. The data are found to be consistent with standard model expectations. A limit at 95% confidence level is set excluding a cross section times branching ratio of 1.1 pb for a top-partner mass of 420 GeV and a neutral particle mass less than 10 GeV. In a model of exotic fourth generation quarks, top-partner masses are excluded up to 420 GeV and neutral particle masses up to 140 GeV. |
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