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Search for New Phenomena with the Mono-jet Signature, and a Direct Measurement of the Z Boson Invisible Width, with the ATLAS Detector at the CERN Large Hadron Collider

A search for new physics in events with an energetic jet and large missing transverse
momentum is performed with the ATLAS detector, using 2011 dataset corresponding
to 4.7 fb−1 integrated luminosity. A model–independent approach is adopted, making
predictions in various kinematic regions sensitive to potentially new physics scenarios.
Data–driven background determination methods are developed to obtain robust predictions
of the Standard Model expectations of the number of events in each probed kinematic
region. No deviation from the Standard Model expectation is observed, and the
results are hence interpreted in the context of the ADD scenario of Large Extra Dimensions,
and pair production of WIMP dark matter candidates. This results in the world’s
tightest constraints on the size of the D-dimensional Planck scale as the fundamental
parameter of the ADD theory. The constraints obtained on Dark Matter suppression
scale are stronger than those obtained from dedicated direct and indirect dark matter
experiments for a large range of WIMP masses.
Furthermore, data-driven estimates of various Standard Model processes contributing to
the mono-jet final state allows a precise direct measurement of the invisible decay width
of the Z boson. This results in a measurement at 5% precision level, comparable to the
results of the L3 experiment, and better than all other LEP direct measurements.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/35940
Date09 August 2013
CreatorsRezvani, Reyhaneh
ContributorsOrr, Robert S.
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
Languageen_ca
Detected LanguageEnglish
TypeThesis

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