Di-Muons Near The Upsilon Resonances In ATLAS

We present measurements of the production cross-section of Upsilon mesons with di-muon final state in pp collision at a 7 TeV center-of-mass energy. The data were collected with the ATLAS detector at CERN with a corresponding integrated luminosity of 1.85 1/fb. We also report a search for a very light CP-odd Higgs boson, a1, decaying to di-muon pairs. Such a light Higgs boson is predicted in Next-to-Minimal extensions of the Supersymmetric Standard Model (NMSSM). We set limits on the production cross-section times branching ratio for a1 masses of 6 – 9 GeV and 11 – 12 GeV, avoiding the region dominated by the Upsilon resonances.