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Abstract

With the commencement of the LHC, a new era in particle physics has begun. By colliding beams of protons at unprecedented energies, the LHC will provide the possibility to probe extensions to the Standard Model of particle physics.

In the following work, a model independent search for new phenomena is conducted in a mono-jet plus missing transverse energy final state. The dataset used corresponds to an integrated luminosity of 4.7 inverse femtobarn of proton-proton collisions at a centre-of-mass energy of 7 TeV recorded by the ATLAS detector in the year 2011. Data-driven methods are developed to estimate the contribution of the largest backgrounds which comprise W/Z+jets production. No excess with respect to processes from the Standard Model is observable. Upper limits are set on the visible cross section at 95% and 90% CL using the frequentist CLs method. New phenomena with a visible cross section bigger than 6.9 (5.5) fb can be excluded at 95% (90%) CL. These limits are translated to lower (upper) limits on the ADD extra dimensions model parameter MD (R). Extra dimensions are excluded for MD values below 4.17 (2.51) TeV for n=2 (6) extra dimensions at leading order cross sections of the theory. The results are also interpreted in terms of dark matter particle candidate, WIMPs pair production scenario.