# Probing the dark sector with the Higgs boson and missing energy at the LHC

Myers, Ava Anne (2022) Probing the dark sector with the Higgs boson and missing energy at the LHC. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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## Abstract

The Standard Model (SM) of particle physics describes a vast range of particle physics experiments across many orders of magnitude. Despite the enormous experimental success of the SM, it does not explain dark matter (DM). I focus on two open questions in particular: (a) What is the nature of DM? (b) How can we use the Higgs boson as a tool to discover DM or other physics beyond the SM?

This thesis presents two searches emphasizing missing energy in the vector boson fusion channel: one for invisible decays of the Higgs boson and one for semi-visible decays. These analyses use 139 fb$^{-1}$ of proton-proton collision data at center-of-mass energy $\sqrt{s} = 13$ TeV with the ATLAS detector at the Large Hadron Collider. Assuming a SM Higgs, an upper limit of 10\%(14\%) expected (observed) at 95\% C.L. is derived for the branching fraction of Higgs to invisible. Results are interpreted in the context of models in which the Higgs acts as a portal to the dark sector, translating to limits on the scattering cross-section of weakly interacting massive particles and nucleons. Future results of the semi-visible Higgs decay will be interpreted in the context of supersymmetry and Higgs portal models.

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## Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
Myers, Ava Anneaam97@pitt.eduaam97
ETD Committee:
Committee ChairHong, Tae Mintmhong@pitt.edutmhong
Committee MemberBoudreau, Josephboudreau@pitt.eduboudreau
Committee MemberKosowsky, Arthurkosowsky@pitt.edukosowsky
Committee MemberBatell, Brianbatell@pitt.edubatell
Committee MemberPaulini, Manfredpaulini@cmu.edu
Date: 12 October 2022
Date Type: Publication
Defense Date: 29 April 2022
Approval Date: 12 October 2022
Submission Date: 16 May 2022
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 218
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: High energy physics, particle physics
Date Deposited: 12 Oct 2022 15:32