The Analysis of the ATLAS Muon Spectrometer performance in H/A search

The impact of the global Muon Spectrometer end-cap misalignment (rotation) relative to the barrel on the reconstruction of the SM H→ 4 μ and MSSM H/A→ 2 μ has been extensively studied. A 1mrad EC rotation, with respect to the axis perpendicular to the beams, reduces the SM Higgs signal by ~ 2% and the MSSM H/A signal by less than 5%. A study of specific sample of Z events with at least one muon in the misaligned region by using the muon-only information has shown that it can be used as a tool for revealing the problem of misalignment in order to be corrected off-line. The ATLAS sensitivity for the H/A→2 μ decay ( mA =300 GeV/c2 and tanβ =30) for the initial detector running, has also been estimated by using the full simulation,. The selection criteria have been optimized for both the direct and the associated production of the Higgs boson. The irreducible Drell-Yan background dominates in the direct production case and overwhelms the signal in such a way that the direct production has a very low signal significance. In the associated production case, the background is the irreducible one, but the most abundant is the background and the selection criteria applied were optimized for its reduction. All samples used were simulated and reconstructed with the full simulation chain. The signal significance was calculated for both analyses separately and for their combination.