The ATLAS inner tracker and the detection of light super-symmetric Higgs bosons

Within the ATLAS-SCT collaboration silicon microstrip detectors with binary readout have been developed for the intermediate layers of the ATLAS tracking and vertexing detectors. Extensive tests of prototype modules in particle beams show that the design meets the stringent requirements. Tests on modules that were previously exposed to a large dose of ionising and non-ionising radiation show that the prototypes maintain an adequate performance after the dose expected during 10 years of LHC operation. The precise reconstruction of particle trajectories and vertices allows to take advantage of the long lifetime of B hadrons to identify jets originating from bottom quarks (b-tagging). This technique can lead to a substantial reduction of the background for many signals. The expected ATLAS b-tagging performance is studied using simulated WH events. In the Minimal Super-Symmetric extension of the Standard Model the Higgs sector consists of five Higgs bosons. The coupling of the neutral Higgs bosons to bottom quarks is strongly enhanced for large values of tan beta. The high rate of h/A/H production in association with bottom quarks opens up decay channels that are not easily detectable in the Standard Model. Here, the decay of h and A bosons into muon pairs is considered. The uncertainties in the rate are discussed, comparing the so-called Matrix Element and shower approaches. While tagging of (one of) the associated b-jets allows a drastic reducion of the dominant Drell-Yan background, the irreducible Zbb background is still considerable. Nevertheless, with a large integrated luminosity (300 fb-1) the h/A -> mumu channel will yield a 5 sigma discovery over an important part of parameter space: tan beta > 14, for 105 < mA < 125.