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# Evidence of Higgs Boson Production through Vector Boson Fusion

 dc.contributor.advisor Kotwal, Ashutosh V dc.contributor.author Cerio, Benjamin C. dc.date.accessioned 2015-05-12T20:44:08Z dc.date.available 2015-09-26T04:30:04Z dc.date.issued 2015 dc.identifier.uri https://hdl.handle.net/10161/9820 dc.description.abstract

The discovery of the Higgs boson in 2012 provided confirmation of the

proposed mechanism for preserving the electroweak $SU(2) \times U(1)$

gauge symmetry of the Standard Model of particle physics. It also

heralded in a new era of precision Higgs physics. This thesis presents a

measurement of the rate at which the Higgs boson is produced by vector

boson fusion in the $WW^{(\ast)}\rightarrow\,\ell\nu\ell\nu$ decay channel. With gauge boson couplings

in both the production and decay vertices, a VBF measurement in this

channel is a powerful probe of the $VVH$ vertex strength. Using

$4.5$~fb$^{-1}$ and $20.3$~fb$^{-1}$ of $pp$ collision data collected

at respective center-of-mass energies of 7 and $8 \tev$ in the ATLAS

detector, measurements of the statistical significance and the signal

strength are carried out in the Higgs mass range $100 \leq m_H \leq 200 \gev$. These measurements are enhanced with a boosted decision

tree that exploits the correlations between eight kinematic inputs in

order to separate signal and background processes. At the benchmark

Higgs mass of $125.36 \gev$, the significance of the data assuming the

background-only hypothesis to be true has been observed to be

$3.2\sigma$ ($2.7\sigma$ expected), constituting evidence of VBF Higgs boson

production. The measured signal strength (ratio of observed cross section times

branching ratio to that predicted by the SM) is

$1.27^{+0.53}_{-0.45}$. The inclusive cross section times

branching ratio is found to be $0.51^{+0.22}_{-0.17}$~pb at $\sqrts = 8 \tev$, consistent with the SM prediction of $0.34$~pb. No

significant deviations from the SM predictions for VBF Higgs boson

production are observed.

dc.subject Physics dc.subject Particle physics dc.subject BDT dc.subject boson dc.subject fusion dc.subject Higgs dc.title Evidence of Higgs Boson Production through Vector Boson Fusion dc.type Dissertation dc.department Physics duke.embargo.months 4
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