PhD Thesis: Searches for Dark Matter and Large Extra Dimensions in Monojet Final States with the ATLAS Experiment
Tuesday 14 June 2016
to 16:00 at
Olof Lundberg (Stockholm University, Department of Physics)
This thesis presents searches for evidence for Weakly Interacting Massive Particles (WIMPs) and Extra Dimensions in
proton-proton collisions recorded by the ATLAS experiment at the CERN Large Hadron Collider (LHC). The WIMP is
one of the main candidates to constitute the particle content of Dark Matter. Extra Dimensions are introduced in several
theories in order to explain the apparent weakness of gravity when compared to the other interactions in Nature. Theories
with WIMPs as well as Extra Dimensions can manifest themselves at the LHC, with experimental signatures characterized
by an energetic hadronic jet associated with large missing momentum. These signatures are known as monojet signatures,
and are investigated in this thesis.
The first analysis is performed using L = 20.3 fb-1 of proton-proton collisions at √s = 8 TeV recorded in the ATLAS Run
1. The second analysis is performed using L = 3.2 fb-1 of proton-proton collisions at √s = 13 TeV recorded in the ATLAS
Run 2. No significant excess over the expected background is found in either of the analyses. New exclusion limits are
set at 95% confidence level on Dark Matter particle production. New limits are also set on graviton production in the socalled
ADD scenario with Extra Dimensions.