Searches for new physics using the ATLAS detector

The search for the Higgs boson has been one of the main motivations for the construction of the Large Hadron Collider. In this study we show that there are new Higgs decay channels, previously neglected by the literature that proceed via internal photon conversion. For the Higgs masses of interest at the CERN LHC in the range of 100-150 GeV, the conversions to pairs of fermions represent a significant fraction of Higgs decays. In addition to the Higgs boson, other particles might be produced, like magnetic monopoles. We present the results of the simulation of the Dirac magnetic monopole production and discuss the feasibility of its detection with the ATLAS detector. This study shows that the magnetic monopole, if it exists, will be detected with the ATLAS detector. The number of events estimated for a luminosity of 1 fb -1 corresponding to the first year of the ATLAS experiment, indicates that the magnetic monopole will be found in the early ATLAS data.