Search for the Higgs boson in $H \to \mu^+ \mu^-$ decays with the ATLAS detector at the LHC

For the last decades, the Standard Model (SM) has been most successful in describing virtually all phenomena of particle physics. All matter particles and all force carriers predicted by the SM have been found and studied experimentally. The last missing piece was the Higgs boson, a result of the mechanism that generates the mass of all massive particles. A candidate boson has now been found by the ATLAS and CMS collaborations. The next experimental step is the measurement of its properties. This includes the coupling to fermions such as muons. The direct decay of Higgs bosons into muon-antimuon pairs is studied in this analysis. A search for this decay is performed using 20.7 fb$^{-1}$ of $\sqrt{s}$ = 8 TeV proton-proton collision data recorded by the ATLAS detector at the LHC in 2012. The invariant mass spectrum of dimuon events is examined using a combined fit of a background and a signal parametrization to this data. No significant excess has been found. Exclusion limits on the strength of this signal have been calculated.