TY  - JOUR
T1  - A search for \(t\overline t\) resonances with the ATLAS detector in 2.05 fb\(^{−1}\) of proton-proton collisions at √s=7 TeV
JF  - European Physical Journal C
N2  - A search for top quark pair resonances in final states containing at least one electron or muon has been performed with the ATLAS experiment at the CERN Large Hadron Collider. The search uses a data sample corresponding to an integrated luminosity of 2.05 fb\(^{−1}\), which was recorded in 2011 at a proton-proton centre-of-mass energy of 7 TeV. No evidence for a resonance is found and limits are set on the production cross-section times branching ratio to \(t\overline t\) for narrow and wide resonances. For narrow Z′ bosons, the observed 95 % Bayesian credibility level limits range from 9.3 pb to 0.95 pb for masses in the range of m Z′=500 GeV to m\(_{Z′}\)=1300 GeV. The corresponding excluded mass region for a leptophobic topcolour Z′ boson (Kaluza-Klein gluon excitation in the Randall-Sundrum model) is m\(_{Z′}\)<880 GeV (m\(_{gKK}\)<1130 GeV).
KW  - dilepton invariant mass
KW  - dilepton channel
KW  - jet channel
KW  - top quark mass
KW  - heavy flavour quark
KW  - reconstructed mass spectrum
KW  - muon channel
KW  - single top production
KW  - electron energy deposition
KW  - multijet background
KW  - non-prompt lepton
KW  - light quark jet
KW  - jet sample
KW  - pair invariant mass
KW  - event selcetion cut
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-127959
VL  - 72
IS  - 2083
ER  - 
TY  - JOUR
T1  - Search for doubly charged Higgs bosons in like-sign dilepton final states at √s=7 TeV with the ATLAS detector
JF  - The European Physical Journal C
N2  - A search for doubly charged Higgs bosons decaying to pairs of electrons and/or muons is presented. The search is performed using a data sample corresponding to an integrated luminosity of 4.7 fb\(^{−1}\) of pp collisions at √s = 7 TeV collected by the ATLAS detector at the LHC. Pairs of prompt, isolated, high-p\(_T\) leptons with the same electric charge (\(e^±e^±, e^±μ^±, μ^±μ^±\)) are selected, and their invariant mass distribution is searched for a narrow resonance. No significant excess over Standard Model background expectations is observed, and limits are placed on the cross section times branching ratio for pair production of doubly charged Higgs bosons. The masses of doubly charged Higgs bosons are constrained depending on the branching ratio into these leptonic final states. Assuming pair production, coupling to left-handed fermions, and a branching ratio of 100 % for each final state, masses below 409 GeV, 375 GeV, and 398 GeV are excluded for \(e^±e^±, e^±μ^±\), and \(μ^±μ^±\), respectively.
KW  - background expectation
KW  - cross section time
KW  - acceptance time efficiency
KW  - partial decay width
KW  - WZ production
KW  - extrapolation factor
KW  - dilepton mass
KW  - charge misidentification
KW  - systematic uncertainty
KW  - non-prompt lepton
KW  - neutral Higgs boson
KW  - producation cross section
KW  - invariant mass distribution
KW  - MC simulation
KW  - leptonic final state
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-129540
VL  - 72
IS  - 2244
ER  - 
TY  - JOUR
T1  - Search for heavy neutrinos and right-handed W bosons in events with two leptons and jets in pp collisions at \(\sqrt{s}\)=7TeV with the ATLAS detector
JF  - The European Physical Journal C
N2  - This letter reports on a search for hypothetical heavy neutrinos, N, and right-handed gauge bosons, W R, in events with high transverse momentum objects which include two reconstructed leptons and at least one hadronic jet. The results were obtained from data corresponding to an integrated luminosity of 2.1 fb\(^{−1}\) collected in proton–proton collisions at √s=7 TeV with the ATLAS detector at the CERN Large Hadron Collider. No excess above the Standard Model background expectation is observed. Excluded mass regions for Majorana and Dirac neutrinos are presented using two approaches for interactions that violate lepton and lepton-flavor numbers. One approach uses an effective operator framework, the other approach is guided by the Left–Right Symmetric Model. The results described in this letter represent the most stringent limits to date on the masses of heavy neutrinos and W\(_R\) bosons obtained in direct searches.
KW  - dilepton invariant mass,
KW  - heavy neutrino
KW  - non-prompt lepton
KW  - Anti-k Jet
KW  - fake lepton
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-127796
VL  - 72
IS  - 2056
ER  -