Search for New Physics Beyond the Standard Model in Dijet Events at the LHC

Searches for new phenomena in LHC proton-proton collisions with the ATLAS detector, using events with at least two high transverse momentum jets were preformed measuring the invariant mass and the angular distribution of the two leading jets. All results are consistent with the predictions of the Standard Model. The angular analysis was performed at a centre- of-mass energy of sqrt(s) = 8 TeV using an integrated luminosity of 17.3/fb. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario was excluded at 95% confidence level. A mass resonance search was done for the first time at ATLAS using a trigger level analysis at a center-of-mass energy of sqrt(s) = 13 TeV with an integrated luminosity of 3.4/fb. No resonance was found and limits were set on generic Gaussian resonances and on a simplified model of a leptophobic axial-vector boson mediator to a dark sector, Z′. In addition, this thesis summarises a theoretical-experimental effort to advocate the use of simplified dark matter models as benchmark models for analyses searching for new physics and the performance of quality tests for the TGC detectors towards their use as part of ATLAS experiment.