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Title: A search for supersymmetry in √s=13 TeV proton-proton collisions with the CMS detector at the LHC
Author: Elwood, Adam Christopher
ISNI:       0000 0004 6421 2539
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
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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.
Supervisor: Tapper, Alex Sponsor: Science and Technology Facilities Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral