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Measuring jet substructure in topologies containing W, top and light jets with the ATLAS detector

Vaidya, Amal; (2020) Measuring jet substructure in topologies containing W, top and light jets with the ATLAS detector. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

The use of substructure information has become ubiquitous in the study of hadronic jets, primarily for jet classification. Recent developments in jet grooming techniques have facilitated analytical calculations of jet substructure variables which, coupled with their frequent use, motivate a set of precision measurements of these variables. This thesis presents work undertaken on the ATLAS detector with a focus on jet substructure using data collected during 2016 in the second run of the Large Hadron Collider. Firstly, the development of a substructure based jet classifier is presented. A large dataset obtained from simulation is used to define a substructure based classifier in order to separate jets from the hadronic decays of W bosons and top quarks from light quark and gluon jets. Its performance is also discussed in the context of ATLAS physics analyses. Secondly a measurement of a large number of jet substructure variables is presented. The measurement uses data collected in 2016 and is done in three distinct regions of phase space, one selecting light jets from inclusive multijet events and the other two selecting top quark and W boson jets from tt ̄ events. A single jet trigger is used to select events with two central jets and no leptons in for the inclusive jet selection. Semi-leptonic tt ̄ events are selected where the leptonic top is tagged and the recoiling hadronic system is probed. Top quark and W boson jets are separated primarily based on the angular separation of the jet from the closes b-tagged jet, with additional requirements on the jet mass. A novel method of bottom-up calorimeter cluster based uncertainties was used and the relevant substructure distributions are presented after being corrected for detector effects.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Measuring jet substructure in topologies containing W, top and light jets with the ATLAS detector
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10091560
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