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A search for supersymmetry in $\sqrt{s}=13~\tev$ proton-proton collisions with the CMS detector at the LHC

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Title: A search for supersymmetry in $\sqrt{s}=13~\tev$ proton-proton collisions with the CMS detector at the LHC
Authors: Elwood, Adam
Item Type: Thesis or dissertation
Abstract: An inclusive search for supersymmetry with jets and missing transverse energy is presented. Data from √s = 13 TeV pp-collisions with a total integrated luminosity of 12.9 fb^(−1) delivered by the LHC and collected by the CMS detector are analysed. The dominant quantum chromodynamic multijet background is strongly suppressed with several kinematic variables, which are also used to discriminate between Standard Model and supersymmetric processes. The observed events are found to be compatible with the expected contributions from Standard Model processes. This result is interpreted in the context of simplified supersymmetric models of gluino and third-generation squark production. The mass of the gluino, bottom squark and top squark are excluded to 1775, 1025 and 875 GeV respectively. In preparation for the collection of √s = 13 TeV data by CMS, the jet algorithm for the Level-1 trigger is upgraded. The new algorithm allows for dynamic pileup subtraction and takes advantage of hardware upgrades to the trigger. The performance of different types of pileup subtraction are evaluated and the most promising algorithm, chunky-donut subtraction, is chosen. The algorithm is found to give a significant performance improvement and has been used to collect data from 2016 onwards.
Content Version: Open Access
Issue Date: Apr-2017
Date Awarded: Jul-2017
URI: http://hdl.handle.net/10044/1/49220
DOI: https://doi.org/10.25560/49220
Supervisor: Tapper, Alex
Sponsor/Funder: Science and Technology Facilities Council (Great Britain)
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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