Abstract
The ATLAS detector at the LHC is used to search for high-mass states, such as heavy charged gauge bosons (W′), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.7 fb−1. No excess beyond Standard Model expectations is observed. A W′ with Sequential Standard Model couplings is excluded at the 95 % credibility level for masses up to 2.55 TeV. Excited chiral bosons (W ∗) with equivalent coupling strength are excluded for masses up to 2.42 TeV.
Highlights
High-energy collisions at the CERN Large Hadron Collider provide the opportunity to search unexplored regions for physics beyond the Standard Model (SM) of strong and electroweak interactions
A search is performed for the charged partners, denoted W ∗, of the chiral boson excitations described in Ref. [6] with theoretical motivation in Ref. [7]
The analysis presented here identifies event candidates in the electron and muon channels, sets separate limits for W /W ∗ → eν and W /W ∗ → μν, and combines these assuming a common branching fraction for the two channels
Summary
High-energy collisions at the CERN Large Hadron Collider provide the opportunity to search unexplored regions for physics beyond the Standard Model (SM) of strong and electroweak interactions. Events are recorded if a muon with pT > 40 GeV is found in the muon spectrometer These are the same pT thresholds used in the previous analysis and, despite stricter hit requirements imposed for the higherluminosity data, the muon trigger efficiency remains 80– 90 % in the regions of interest. A hit in the first pixel layer is required to reduce background from photon conversions in the inner detector material These requirements result in about 90 % identification efficiency for electrons with ET > 85 GeV and a 2 × 10−4 probability to falsely identify jets as electrons before isolation requirements are imposed [9]. The missing ET in each event is evaluated by summing over energy-calibrated physics objects (jets, photons and leptons) and adding corrections for calorimeter deposits away from these objects [10] This is an improvement over the previous analysis which did not include the energy calibration. The uncertainty on this measurement is 3.9 % [11, 12]
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