Title: Monojet Events: a Journey into the Standard Model and Beyond


The Standard Model is currently the theory which describes the most fundamental constituents of matter and the forces which govern their interactions. Since the start-up of the LHC accelerator, the ATLAS detector has collected sufficient data to allow tests of this theory at the smallest distance scales ever probed. The objective is to find significant deviations between the observed data and the Standard Model predictions, revealing the existence of new phenomena. For example, some theories in which the universe has more than 4 space-time dimensions predict that LHC collisions could produce gravitons - the particles responsible for the gravitational interaction. Such events would feature a single jet of hadronic particles in the detector and a large amount of “missing” momentum (monojet events). In order to gain credibility, any new physics discovery needs to be preceded by a thorough examination of the Standard Model phenomena in the new LHC experiments. In this presentation, I will show how the precise studies of Standard Model phenomena made by the ATLAS collaboration in 2010 can be developed to improve the sensitivity to new physics. I will illustrate this idea in the context of searches for extra dimensions with monojet events. I will also present the results obtained at the Tevatron with the CDF detector for similar searches, and compare them with ATLAS results.