A Measurement of the ATLAS Di-Muon Trigger Efficiency in Proton-Proton Collision at √s = 7 TeV

摘要

The B physics programme of the ATLAS experiment includes measurements of production cross sections, searches for rare B-decay signatures which are sensitive to new physics at the TeV energy scale and studies of CP violation effects in B-events, such as Bs0 → J/ψφ and Bd0 → J/ψKs0. The key to the detection of these B signals in ATLAS is to achieve a high trigger efficiency for low-pT di-muon events, whilst keeping an acceptable trigger rate. ATLAS developed two separate approaches for triggering on di-muon events from resonances such as J/ψ and Upsilon (γ). The first approach is to start from a di-muon trigger selected at Level-1 while the second is based on dedicated Level-2 algorithms. The performance for these triggers has been studied using collision data at √s = 7 collected in 2011.