Search for New Phenomena in t(t)overbar Events with Large Missing Transverse Momentum in Proton-Proton Collisions at root s=7 TeV with the ATLAS Detector

A search for new phenomena in t¯t 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...

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Bibliographic Details
Main Author: Onofre, A. (author)
Other Authors: Castro, Nuno Filipe Silva Fernandes (author), ATLAS Collaboration (author)
Format: article
Language:eng
Published: 2012
Subjects:
Online Access:http://hdl.handle.net/1822/48834
Country:Portugal
Oai:oai:repositorium.sdum.uminho.pt:1822/48834
Description
Summary:A search for new phenomena in t¯t 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.