## Publicly Accessible Penn Dissertations

2015

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

Physics & Astronomy

Elliot D. Lipeles

#### Abstract

This thesis presents the first search of an invisibly decaying Higgs

boson produced via Vector Boson Fusion on ATLAS. The dataset used for

the analysis corresponds to 20.3fb$^{-1}$ of proton-proton collisions

at $\sqrt{s} = 8$ TeV recorded at the Large Hadron Collider in 2011

and 2012. An upper bound limit is set at 95\% confidence level on the

invisible branching fraction of the Higgs Boson. A limit of 28\% is

observed (34\% expected) and interpreted using the Higgs portal model

to set a limit on the dark matter-nucleon cross section. The unique

jet final state created by Vector Boson Fusion provides a stronger

signal to background ratio than other invisibly decaying Higgs

channels. The Vector Boson Fusion analysis presented resulted in the

strongest constraint on dark matter production set by a hadron

collider.

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