Measurements of Higgs Boson Couplings and Constraints on New Physics with the ATLAS Detector

The couplings of the Higgs boson are measured by the ATLAS experiment using the LHC Run I data sample. The data analyzed involve decays of the Higgs boson to pairs of photons, $Z$ bosons, $W$ bosons, $\tau$ leptons, or $b$-quarks respectively. Evidence for Higgs boson decays into fermion pairs is found with 3.7$\sigma$ significance using the combination of the $bb$ and $\tau\tau$ channels. The measured values and mass dependence of the couplings agree well with the predictions for the Standard Model Higgs boson. The coupling measurements are used to set limits on a composite Higgs boson and a simplified Minimal Supersymmetric Standard Model. A search for the $E_{{\textrm T}}^{\textrm{miss}}$ process is used together with the coupling measurements to constrain a Higgs portal to dark matter.