Publication Date

2018

Document Type

Dissertation/Thesis

First Advisor

Chakraborty, Dhiman

Degree Name

Ph.D. (Doctor of Philosophy)

Department

Department of Physics

LCSH

Nuclear physics

Abstract

This dissertation describes a search for charged Higgs bosons decaying to a tau and a neutrino (H⁺ [right arrow] [tau]⁺[nu][sub t] or the charge-conjugate process) in association with a leptonically decaying top quark, using 36.1 fb⁻¹ of pp collision data collected with [square root]s = 13 TeV by the ATLAS detector. The theoretical motivation, including a review of the Standard Model, is given, along with a description of the ATLAS detector and particle reconstruction. A multi-variate analysis approach uses stochastic gradient boosted decision trees to improve the separation between H^[+/-] signal and background. The semi-leptonic channel described in this thesis is used in combination with a fully hadronic channel to search for charged Higgs bosons in a mass range of 90 GeV [less than or equal to] m[sub H^[+/-]] [less than or equal to] 2000 GeV. Finding no significant excess, limits are set at the 95% confidence level on the charged Higgs production cross section times the branching fraction into [tau][nu] ranging from 4.2 pb to 2.5 fb. These limits are interpreted in the hMSSM benchmark scenario as an exclusion at 95% confidence on tan[beta] as a function of m[sub H^[+/-]]. In this scenario, for tan[beta] = 60, the H^[+/-] mass range up to 1100 GeV is excluded, with all values of tan[beta] exclude for m[sub H^[+/-]] [precedes or equivalent to] 160 GeV.

Comments

Advisor: Chakraborty, Dhiman.||Committee members: Adelman, Jahred; Martin, Stephen.||Includes illustrations.||Includes bibliographical references.

Extent

105 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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