Kelly, Aidan;
(2023)
Measurement of Detector-Corrected Cross-Sections in Events with Large Missing Transverse Momentum in Association with Jets.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
This thesis presents an analysis of events with large transverse missing momentum in association with jets using 139 fb−1 of proton-proton collisions at a centre of mass energy of 13 TeV , that was delivered at the Large Hadron Collider and recorded using the ATLAS detector from 2015 − 2018. The dominant process which contributes to these events is the Z boson decaying to two neutrinos followed closely by the contribution from W bosons decaying leptonically, in which the charged lepton is outside the detector acceptance. The similarity of these processes to Z and W bosons decaying leptonically can be exploited by measuring the one lepton and two lepton regions, and treating the leptons as invisible in order to constrain modelling along with the experimental and theoretical uncertainties. These lepton regions are known as the auxiliary regions. This analysis was performed using three different phase-spaces that are sensitive to different Dark Matter production channels. These three phase-spaces require the ≥ 1 jet , ≥ 2 jet and VBF topologies. The total yield is measured at the detector level and the differential cross section is measured at the particle level as a function of the missing transverse momentum, the dijet invariant mass and the dijet azimuthal angle. Ratios of these cross sections are also presented at the particle level to facilitate comparisons between regions and minimise the systematic uncertainties. These results are interpreted using a likelihood fit and the agree- ment between the modelling and the data is quantified using a χ2 test and p-value. Constraints are made on the axial-vector and pseu- doscalar simplified Dark Matter models and are shown to be competitive with results from the recent dedicated monojet-like search in ATLAS.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Measurement of Detector-Corrected Cross-Sections in Events with Large Missing Transverse Momentum in Association with Jets |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10172889 |
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