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Search for supersymmetry in pp collisions with all-hadronic final states using the αT variable with the CMS detector at the LHC

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Title: Search for supersymmetry in pp collisions with all-hadronic final states using the αT variable with the CMS detector at the LHC
Authors: Mathias, Bryn Lugh Shorney
Item Type: Thesis or dissertation
Abstract: A search for supersymmetry in the exclusive hadronic and missing energy channel is presented on 5 fb-1 of data collected using the CMS detector at the LHC. The data were produced at a center-of-mass energy of 7 TeV. The kinematic discriminator αT is used to select signal events which are then binned in terms of the visible energy per event. The efficiency of the hadronic level one triggers is measured though-out the data taking period and a scheme to reduce the effects of multiple collisions per bunch crossing on the cross section of the trigger paths is studied, implemented and tested in situ. These efficiency measurements are considered in the development of an analysis specific trigger, the performance of which is measured in situ, with the final efficiencies taken into account in the presented analysis. A data driven background estimation method is used to predict the expected yield in the signal regions from Standard Model processes. In the absence of an observed excess, limits are set to the 95% confidence level on the production cross section and masses of new particles. In the context of the Constrained Minimal Supersymmetric Model (CMSSM), squarks and gluinos with a mass of up to 1 TeV are excluded. In terms of simplified models with various light and heavy flavour final states, squarks and gluinos are excluded at a mass of ≈1 TeV for a Lightest Supersymmetric Particle (LSP) mass of up to ≈500 GeV. Natural units (h = c = 1) are used though-out.
Content Version: Open Access
Issue Date: Apr-2013
Date Awarded: Feb-2014
URI: http://hdl.handle.net/10044/1/17844
DOI: https://doi.org/10.25560/17844
Supervisor: Tapper, Alexander
Nash, Jordan
Department: Physics
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Physics PhD theses

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